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The Land Resources of 

North East Nigeria 

Volume 1 


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Nomadic bulls grazing arable stubble. 

Savanna woodland in the background 

11 

Photo: P E Glover

Foreign and Commonwealth Office 

Overseas Development Administration 

The Land Resources of 

North East Nigeria 

Volume 1 


(with an introduction to Volumes 1 - 5 

by the Editor, P. Tuley) 

P.J. Aitchison, M.G. Bawden, D.M. Carroll 

by 

P.E. Glover, K. Klinkenberg, P.N. de Leeuw 

and P. Tuley 

Land Resource Study No. 9 

Land Resources Division, Tolworth Tower 

Surbiton, Surrey, England 

1972

THE LAND RESOURCES DIVISION 

The Land Resources Division of the Overseas Development Administration, 

Foreign and Commonwealth Office, assists developing countries in mapping, 

investigating and assessing land resources, and makes recommendations on 

the use of these resources for the development of agriculture, livestock 

husbandry and forestry; it also gives advice on related subjects to overseas 

governments and organisations, makes scientific personnel available 

for appointment abroad and provides lectures and training courses in the 

basic techniques of resource appraisal. 

The Division works in close co-operation with government departments, 

research institutes, universities and international organisations concerned 

with land resources assessment and development planning. 

The Division ceased to be a part of the Directorate of Overseas Surveys 

in April 1971. 

iv

LIST OP PLATES 

LIST OP TEXT MAPS 

LIST OP DETACHED MAPS 

LIST OP FIGURES 

LIST OP VOLUMES 

PREFACE BY THE EDITOR 

PART 1. 

PART 2. 

PART 3. 

CONTENTS 

INTRODUCTION TO VOLUMES 1-5 

History of the Study 

Abstract 

Resume 

Method 

Bibliographic Studies 

Acknowledgements 

List of Contributors to Volumes 1-5 

INTRODUCTION 

Acknowledgement s 

Abstract 

Resume 

List of Descriptors 

THE ENVIRONMENT 

PHYSICAL ASPECTS 

Location M G Bawden 

Climate P Tuley 

Physiography M G Bawden 

Geology M G Bawden 

Geomorphology M G Bawden 

Hydrology M G Bawden 

Soils 

Vegetation 

Fauna 

HUMAN ASPECTS 

History 

Population 

Communications P Tuley 

REFERENCES 

VOLUME 1 

D M Carroll and K Klinkenberg 

P N de Leeuw and P Tuley 

P J Aitchison and P E Glover 

P Tuley 

P Tuley 

vi 

vi 

vii 

vii 

xi 

xiii 

xiii 

xiii 

xiv 

xiv 

xiv 

XV 

3 

3 

3 

3 

5 

6 

43 

46 

60 

71 

85 

121 

156 

163 

164 

166 

175

LIST OF PLATES 

Frontispiece. Nomadic bulls grazing on arable stubbles 

1/1. Song. View from basalt hill across farmland with Adansonia digitata and 

Acacia albida 54 

1/2. Biu Plateau. General view northward from Tilla Lake with cones and craters 

in the far distance 54 

1/3. The Kadi Escarpment 55 

1/4. Near Pindinga. Exposure of the Pindinga Shale in river bank in 

predominently Gombe Sandstone 55 

1/5. The road to Dikwa across the 'firki' (black cracking clay plains) 69 

1/6. The Bama Ridge just west of Maiduguri 69 

1/7. The Gongola Floodplain 70 

1/8. The Matyoro Lakes 70 

1/9. Near Gulumba. Termitaria on heavy soils in Land System Vil, the Yabiri 

Delta 120 

1/10. Soil erosion at the western foot of the Biu Plateau resulting from 

intensive utilisation of Ferruginous Tropical Soils derived from rocks of 

the Basement Complex 1^ 

1/11. Typical Anogeissus Woodland south of Damboa 127 

1/12. Lannea humilis. A typical gregarious clump showing the low contorted habit 127 

1/13. Acacia seyal Tree Savanna on vertic clay flat 141 

1/14. Land System Vel, the Arege Plain. Cordia rothii/Acacia raddiana Tree and 

Shrub Savanna with thickets of Salvadora persica 141 

1/15. Hyphaene Palm Bush on the Yobe Floodplain 155 

1/16. Riparian Woodland on the course of the river Yedseram, north of the Bama 

Ridge 155 

LIST OF TEXT MAPS 

1. Location 7 

2. Major relief units 9 

3. Mean annual rainfall 11 

4a, 4b. Mean monthly rainfall 18,19 

5a, 5b. Mean monthly temperature 26,27 

6a,6b. Mean monthly maximum temperature 30, 31 

7a, 7b. Monthly analysis of wind direction 33,35 

8. Length, start and end of the wet season 41 

9. Geology 47 

vi

ÏO- Hydrogeology 

11- Catchment areas 

HA. Areas covered t>y reconnaissance soil surveys 

12- Population d e n s i t y 

13- Ethnic groups 

14- Administrative u n i t s 

15- Communications 

1. Relief 

2- Geomorphology 

3- Soils 

4- Vegetation 

L I S T OF DETACHED MAPS 

LIST OF FIGURES 

1. Distribution o f r a i n f a l l for selected stations 

2. Rainfall d i s p e r s i o n diagrams for selected stations 

3- Mean daily h o u r s o f bright sunshine and cloud cover 

4. Mean s a t u r a t i o n d e f i c i t at 0900 and at 1500 hours 

5- Eco-climatic z o n e s 

6. Geological s e c t i o n s 

"7. Generalised s o i l p a t t e r n s 

8. Soil patterns on Basement Complex 

9. Soil p a t t e r n s on Cretaceous Sandstones 

10. Soil p a t t e r n s o n Transitional Formations 

11. Clay content o f t h r e e soils on Kerri Kerri Sandstone 

12- Soil p a t t e r n s on toasa.lt 

13- Soil p a t t e r n s o n sanely facies of Chad Formation 

14. Soil p a t t e r n s i n a l l u v i a l areas 

15. Environment a l r e l a t ionships of the major woody plant communities 

16- Alluvial c o m p l e x e s — woody vegetation. Schematic relationship of the 

major plant «communit i e s 

vil 

73 

75 

84 

167 

169 

171 

173 

21 

23 

37 

38 

39 

52,53 

86 

97 

100 

103 

105 

108 

114 

115 

124 

125

INTRODUCTION TO 

VOLUMES 1- 5

LIST OF VOLUMES 

LAND RESOURCE STUDY NO. 9. THE LAND 

RESOURCES OF NORTH EAST NIGERIA. 

EDITED BY P TULEY 

Volume 1 The Environment (with an Introduction to Volumes 1-5) (1972) 

Volume 2 Tsetse and Trypanosomiasis (1970) 

Volume 3 The Land Systems (1972) 

Volume 4 Present and Potential Land Use (1972) 

Volume 5 Appendixes and Tables (1972) 

xi

HISTORY OF THE STUDY 

PREFACE TO VOLUMES 1 - 5 

by the Editor, P. Tuley 

This study is published with the authority of the Nigerian Federal and North-Eastern State 

Governments. The data collected and collated, and the recommendations evolved during the 

course of the investigations associated with this study, formed the basis for discussion at a 

Land Resources Conference organised by the North-Eastern State Government in August 1969 

(Land Resources Conference, Maiduguri, 1970). The final approved recommendations presented 

in this study are essentially those discussed and submitted to the Nigerian authorities at 

that meeting. 

Political changes in Nigeria have resulted in the creation of 12 states. The area covered by 

this study (Text Map 1), the boundaries of which were negotiated by the former Northern 

Nigeria Government and predate the present structure, falls entirely within the present 

North-Eastern State. The intention was to investigate an area of Nigeria north of the Benue 

river and east of 10° longitude. As explained in the Location Section, Volume 1, the 

boundary has been adjusted slightly in the light of subsequent developments. 

The origins of the study lie in two United Kingdom Technical Assistance Projects requested by 

the former Northern Nigeria Government. The first request was for an investigation commencing 

in 1965 by a team under the leadership of Dr P E Glover on the feasibility of eradicating 

tsetse from a substantial area in the northeast of Nigeria. Details of the project are given 

in Volume 2 and draft reports have been submitted to the Nigerian authorities (Glover and 

Aitchison, 1967; Lesslie, 1968). The second request was for an investigation of the land 

resources of the area to be carried out by the Land Resources Division. Work on this project 

commenced in 1966 and an interim report was subsequently submitted to the Nigerian 

authorities (Bawden etal., 1968). 

During the period of these projects the Soil Survey Section, Institute for Agricultural 

Research, Ahmadu Bello University, Samaru, Zaria, agreed to a programme expanding its existing 

soil survey coverage in the area. Details of this programme are contained in the Soils 

Section of Volume 1. 

With this programme of synchronised and interrelated projects it quickly became apparent that 

unnecessary duplication could easily occur. In consequence, it was agreed by all concerned 

that the Land Resources Division should prepare and publish a consolidated study. 

ABSTRACT 

This study (Volumes 1-5) comprises the quantified reconnaissance assessment of the land 

resources of 176 000 km 2 (68 000 mi 2 ) in North East Nigeria. The fundamental environmental 

factors are described. A full volume is devoted to the problems and eradication of the 

tsetse fly while another classifies the area into 123 land systems with descriptions provided 

at the land facet level. The present land use of the area is described and recommendations 

are made for future land use. 

(An abstract of Volume 1 will be found in Volume 1, Part 1.) 

RESUME 

Cette etude (Tomes 1/5) comprend une reconnaissance quantifiee des ressources terrestres de 

176 000 km 2 du nord-est du Nigeria. Les elements fondamentaux du milieu sont decrits. Un 

volume complet est consacre' aux problèmes et ä 1'extirpation de la mouche Tse'tse, tandis 

qu'un autre classe la re'gion dans 123 land systems (zones e'cologiques), avec des descriptions 

detaillees des unites constitutives de chaque zone ecologique. L'usage actuel de la terre 

dans la zone est de'crit, et des recommendations sont faites pour son usage ä 1'avenir. 

Un re'sume de Tome 1 se trouve dans la première Partie de ce tome-ci. 

xiii

METHOD 

This study has attempted to apply the Land System concept, broadly in the sense of 

Christian and Stewart (1964), to the environmental classification of a substantial area, 

176 000 km 2 (68 000 mi 2 ). Description of the main parameters at the land facet level for 123 

land systems has also been attempted and the whole employed as a framework within which land 

use data and recommendations are classified and presented. The study has been largely 

agroforestal in emphasis but it is hoped it will prove useful in such other fields as 

engineering and industrial planning. 

The data and recommendations are presented in terms of "natural units' , but since State 

planning procedures are largely based on administrative units, a set of administrative overlays 

for the larger scale maps has been provided for the North-Eastern State authorities. 

Attention should be drawn to the efforts in Volume 4 and in the appendices in Volume 5, to 

provide areal estimates of land facets and the vegetation/land use patterns upon them. 

Subsequently, quantified data, fundamental to land use and development planning, can be 

derived from the estimates. 

BIBLIOGRAPHIC STUDIES 

Prom the large quantity of bibliographic material accumulated during the project only 

references strictly relevant to each volume have been retained. It is however being arranged 

for a subject land resource bibliography to be issued in conjunction with this study 

(Posnett et al., 1972). 

ACKNOWLEDGEMENTS 

To thank everyone associated with this study would be a monumental task as there must be few 

relevant organisations and arms of government in Nigeria that have not assisted willingly and 

generously in the implementation of the various projects. To complicate matters further, 

following administrative changes, some of the organisations deeply involved at the inception 

of the projects no longer exist. Special mention must however be made of the efforts and 

support, often in times of difficulty and even national emergency, of : 

The Ministry of Animal and Forestry Resources and Ministry of Agriculture of the 

former Northern Nigerian Government (whose work with regard to this project later 

devolved upon the North-Eastern State Ministry of Natural Resources); the Federal 

Tsetse Control Unit, including elements of the former Ministry of Health's Sleeping 

Sickness Service; and the Interim Common Services Agency. 

The Institute for Agricultural Research, Ahmadu Bello University, Samaru, primarily 

through the agency of the Soil Survey Section and the Shika Research Station. 

The British High Commission and Trade Commission, Kaduna. 

A study of this nature must use the accumulated knowledge of organisations and individuals 

conversant with the project area. Every attempt has been made to acknowledge sources of data 

and individuals in the text of the report and the assistance of all concerned is most 

gratefully acknowledged. The organisations primarily concerned are : 

Federal Ministry of Agriculture and Natural Resources 

North-Eastern State, Ministry of Natural Resources 

North-Eastern State, Ministry of Works 

North-Eastern State, Ministry of Health 

Federal Surveyor General 

Surveyor General, ICSA (Interim Common Services Agency) 

Surveyor General, North-Eastern State 

Nigerian Geological Survey 

Federal Tsetse Control Unit 

Nigerian Institute for Trypanosomiasis Research 

Institute for Agricultural Research, Ahmadu Bello University, Samaru 

Savanna Forestry Research Station, Samaru 

Nigerian Meteorological Services 

xiv

United States Agency for International Development 

UNESCO/PAO Chad Basin Commission 

Commonwealth Development Corporation 

Outside Nigeria the assistance of the following contributed greatly to the study : 

ORSTOM (Office de Recherche Scientifique et Technique Outre-Mer, Prance) 

M M Bocquier and M M Gavaud 

The Department of Geography, Liverpool University, United Kingdom 

Mr R A Pullan 

The Atlas Computer Laboratory, Chilton, United Kingdom 

Mr J E Hailstone and Mrs J Lay 

The Royal Botanic Gardens, Kew, United Kingdom 

Mr P N Hepper and Dr W D Clayton 

In conclusion, thanks must-go to all local administrators, officials and citizens whose 

courtesy, kindness and willingness to assist contributed so much to the effectiveness of the 

field work. 

LIST OF CONTRIBUTORS TO VOLUMES 1-5 

P J AITCHISON 

M G BAWDEN 

D M CARROLL 

P E GLOVER 

K KLINKENBERG 

P N de LEEUW 

A LESSLIE 

P TULEY 

Started his tropical service in Swaziland and has been actively engaged in 

tsetse survey and control in Kenya and Nigeria for 13 years prior to joining 

the present project. Now farming in the United Kingdom. 

Joined the Forestry and Land Use Section of the Directorate of Overseas 

Surveys (the forerunner of the Land Resources Division) in 1959 as 

geomorphologist. Has worked primarily in West and Southern Africa. 

A member of the United Kingdom Overseas Pool of Soil Scientists from 1962 

until its absorption by the Land Resources Division in 1965. Worked mainly 

on soil survey in the West Indies, Southern and West Africa. In 1968 joined 

the Soil Survey of England and Wales. 

Formerly Chief Zoologist to the Kenya Veterinary Department. In 1965 

appointed as a Land Use Adviser to the United Kingdom Ministry of Overseas 

Development to take charge of the tsetse investigations described in this 

study. Presently working on the Tsavo National Park Project in Kenya. 

Joined the Soil Survey Section of the Institute for Agricultural 

Research, Samaru, in 1957. Has been largely concerned with Soil Survey in 

the Northeast of Nigeria and has been Head of the Section since 1967. 

Joined the Ministry of Agriculture, Northern Nigeria, in 1960 as ecologist/ 

soil surveyor. In 1963 became a research fellow of the Institute for 

Agricultural Research primarily concerned with rangeland problems at the 

Shika Research Station, where he is now Officer-in-Charge. 

Formerly with the Ghana and Kenya Departments of Agriculture, from 1946 until 

retiring as Director of Agriculture, Eastern Region, Kenya, in 1964. Joined 

the Land Resources Division in 1967 on completion of the United Kingdom 

Technical Assistance project associated with this study. 

Formerly Regional Botanist then Head of the Agricultural Research and Training 

Station, Umudike, Nigeria. Joined the Land Resources Division in 1965 

and now Project Leader for operations in the north of Nigeria. Acted as 

coordinating editor for this report. 

xv

VOLUME 1 

PARTS 1- 3

ACKNOWLEDGEMENTS 

PART 1. INTRODUCTION 

Sources of data are quoted in the text and full acknowledgements are given in the 

Introduction to Volumes 1-5 at the beginning of this study. 

ABSTRACT 

The volume is devoted to the description of the physical and human environment of the project 

area. Present land use is however omitted and is described in Volume 4. An account is given 

of the geology, geomorphology, hydrology and climate. The soils and soil patterns are described 

and the system of soil classification employed is explained. The vegetation of the 

area is classified into 20 phytosociological units, and the species composition of each 

displayed in tabular form. In addition to text maps there are maps of Relief, Geomorphology, 

Soils and Vegetation at a scale of 1:1 000 000. 

RESUME 

On decrit le milieu physique et humain de la zone du projet. On ne discute pas 1'utilisation 

actuelle de la terre, qui sera decrite dans le Volume 4. Un recit est donne de la geologie, la 

geomorphologie, 1'hydrologie et du climat. Les sols et leurs groupements sont de'crits et le 

Systeme de classer les sols est explique. La ve'getation de la zone est classee dans 20 

unites phytosociologiques, et la composition par espèces de chacune est presentee en forme 

de tableau. Le relief, la ge'omorphologie, les sols et la ve'ge'tation sont indiques sur des 

cartes ä 1*echelle de 1:1 000 000. 

DESCRIPTORS FOR COORDINATE INDEXING 

Climate, geology, geomorphology, soil survey, cartography, hydrology, land resource, fauna, 

plant ecology, vegetation survey, communications, demography, North, East, Nigeria. 

3

PART 2. THE ENVIRONMENT 

LOCATION 

by 

M G Bawden 

The area covered by this land resource project is shown in Text Map 1. It is bounded in the 

south by the Benue river and in the east and north by the frontier with the Cameroon and 

Niger Republics. The western boundary is generalised on the small scale location map as a 

straight line following 10° longitude; in detail it is more complex: from Matsena in the 

north through Hadejia to Azare it follows the 10° line of longitude; from Azare it runs east 

to Misau and then southwards separating the Bauchi Plains from the Kerri Kerri Plateau (see 

Text Map 2). Prom the south of the Kerri Kerri Plateau the boundary follows an irregular 

line southeast to the Benue, downstream from the confluence with the river Pai. 

The reason for the irregular boundary is that, at the time of the fieldwork, a further land 

resource reconnaissance was known to be planned to cover the area immediately to the west of 

this project. To the north of Misau a similar landscape extends westwards from Gashua to 

Kano and 10° longitude was used as a convenient dividing line. South of Misau the landscape 

changes markedly between the Kerri Kerri Plateau and the Bauchi Plains to the west and the 

boundary follows this natural division. South of the Kerri Kerri Plateau the character of 

the Benue Valley west of the Pai river is more akin to the landscape further west and it will 

be covered by the new project. 

In the south the North East project joins the area covered by the reconnaissance of the land 

resources of Southern Sardauna and Southern Adamawa (Bawden and Tuley, 1966) the northern 

limit of which was the Benue river extending eastwards from the 10° line of longitude to the 

Cameroon frontier. 

5

GENERAL CIRCULATION 

CLIMATE 

by 

P Tuley 

The gross characteristics of the West African climate are largely determined by the 

properties and movement of the so-called Inter-Tropical Convergence Zone (ITCZ). The northward 

progression of the sun during the summer season in the northern hemisphere brings rainbearing 

southwesterly winds to the project area. Water for plant growth becomes available 

under conditions of increasing day length, and there is a close correlation between rainfall 

pattern and latitude. Conversely, with the southward movement of the sun in winter, northerly 

and northeasterly dry winds blow from the Sahara. Accounts of this phenomenon of relevance 

to the project area are available in Clackson (1957), Cochemé and Franquin (1967) and 

Hamilton and Archbold (1945). In the project area there is a marked southerly displacement, 

particularly in the extreme northeast of some of the climatic parameters. Cochemé and 

Franquin (1967) suggest that this is probably due to a 'preferred position' of a high pressure 

cell lying to the northwest of Chad. 

The southern sector of the project area also exhibits climatic anomalies due to orographic 

effects, while the low-lying Benue Valley appears to have a separate climatic regime for at 

least part of the year. 

AVAILABILITY OF RECORDS 

The prime source of data for this report has been the Monthly Summary issued by the Nigerian 

Meteorological Service (NMS). There is a reasonable distribution of stations within the 

project area recording rainfall, but there are key areas for which data are not available, 

are incomplete or are of short duration. In addition, there is a small group of stations, 

usually associated with airfields, where a wider range of measurements are taken: Maiduguri, 

Yola, Potiskum and Nguru. Limited data have been collected from reports giving records not 

shown in the Summaries and these sources are acknowledged in the text. There are also a few 

stations falling just outside the area, in Nigeria and adjacent countries, which provide useful 

records. In Volume 5 a map showing the location of the recording stations is given, the 

sources of publications are listed and suggestions made for the siting of new stations in 

the project area. 

To improve presentation, tables of selected data have also been placed in Volume 5 and only 

summarised data are given here. In association with other projects in Nigeria it is intended 

to present a separate and more detailed analysis of the available data at a later date. 

PRECIPITATION 

Mean Annual Rainfall (1949-1961) 

The highest recorded mean annual rainfall (m.a.r.) in the project area is from Bazza, in 

the foothills of the Mandara range, with 1 125 mm (44.3 in) and the lowest from Abadan, in 

the extreme northeast of the area, with 290 m (11.5 in). The mean annual isohyets are shown 

in Text Map 3. To the north of the 890 m (35 in) isohyet the typical latitudinal trend is as 

expected, allowing for the dipping of the isohyets to the eastward described under General 

Circulation, and for some local southward displacement in the east behind the Biu Plateau and 

the northern tip of the Mandara range. To the south of this line a more complex situation 

arises. The 1 015 mm (40 in) isohyet enters the project area from the west just north of 

ll°ti. Near Misau it makes a sharp bend turning back on itself and progressing southwestward 

to the area of the confluence of the Wase and Donga rivers with the Benue. Here it turns 

again sharply eastward and, just south of the Benue, it follows a more typical east-west 

alignment passing into the Cameroon Republic just south of the Benue-Paro confluence 

(Genieux, 1960). In effect there is a spectacular broadening of the belt between the 

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1 015 mm (40 in) and 890 mm (35 in) isohyets, roughly enclosed in a rectangle bounded by 

10°- 13° longitude and 9°- ll° N. Within this rectangle lies a distinct isolated belt of 

1 015 mm (40 in) m.a.r. about 30-50 km (20-30 mi) wide running from the Hawal - Gongola confluence 

to the Mandara range. In addition, smaller areas with a m.a.r. above 1 015 mm 

(40 in) and below 890 (35 in) also occur within the rectangle, associated with localised 

orographic effects. Where the presence of large atypical areas is suspected, but not fully 

substantiated, they are indicated by broken blue lines in Text Map 1. This feature is discussed 

further under eco-climatic zones. 

Mean Monthly Rainfall 

The extent and distribution of mean monthly rainfall is shown on Maps 4a and 4b. The 

monthly means range from 450 mm (18 in) to zero. The period November - February is virtually 

rainless over the greater part of the project area and the rains commence in March -April 

sweeping up from the southwest and west to reach their peak in August. From September 

onwards the rains retreat southwestwards and the annual northwest/southwest oscillation is 

clearly observable on the maps. (See pp. 18-42 for climatic maps and diagrams.) 

Distribution of Rainfall 

Figure 1 shows the distribution of the occurrence of annual rainfall for a restricted number 

of stations by (25 mm) 1 in integers and grouped 5 in (125 mm) units. Over the period 

examined it can be seen that low annual rains are atypical of the stations with a m.a.r. of 

more than 1 015 mm (40 in). Yola occupies an intermediate position with a wider scatter of 

records about the mean. In the northern group low rains occurred at Maiduguri in 6 years 

out of 40 and at Potiskum in 2 years out of 26. The lowest record occurred in the same year 

of drought, 1940, for both stations. The deviation from normal distributions indicated by 

the grouped histograms in Figure 1 should be noted and Figure 2 shows a range of typical 

rainfall patterns for selected stations. 

Twin-Peak Distributions 

The annual distribution of rainfall in twin peaks is well known in southern Nigeria and 

involves what is commonly termed the 'little dry season' in the month of August between twin 

peaks of rainfall in July and September (Ireland, 1962). This is associated with the double 

passage northward and southward of the ICTZ at the time when it usually reaches its most 

northerly position. There are indications that the feature occurs in the south and southwest 

of the project area, where the secondary minimum is July and not August (Kwojeffa is a 

marked exception). It appears to be confined to the rectangle between the 890- 1 015 mm 

(35-40 in) isohyets described under Mean Annual Rainfall, where, irrespective of total rain 

fall, there is a tendency for the predominance of August rainfall to be diminished with an 

additional tendency towards twin-peak distributions. 

TEMPERATURE 

Temperature records are available in the NMS Monthly Summary for four stations within our 

area, Maiduguri, Potiskum, Yola and Nguru. Fortunately there are some peripheral stations 

also recording temperature and Klinkenberg et al. (1963) give some figures for Gombe. From 

the restricted data available the broad trends of the temperature regime are shown on Text 

Maps 5a, 5b, 6a and 6b. Temperatures tend to be higher to the northeast and lower towards 

the southwest, with the marked exception of the Benue Valley which, particularly in the 

period December - March, experiences a higher temperature than the country immediately to the 

north. Excepting this, the area in general experiences the coolest temperatures in 

December - January, with monthly means falling to 20.0-22.5°C (68.0° - 72. 5°F). Night temperatures 

of the order of 8°C(46°F) are recorded during this period and, at high altitude, 

lower temperatures may be experienced. In the Benue Valley,minimum temperatures rarely fall 

below 13°C (55°F). Temperatures reach their maximum at the onset of the rains in April -May. 

In April itself mean maximum temperatures over most of the area are in excess of 39°C 

(102°F) while mean temperatures are of the order of 31°C (88°F). Maximum day temperatures 

of around 43°C (110°F) are not uncommon in the north and northeast. During the rains an 

intermediate regime with "lower and more uniform temperatures occurs. Throughout the area 

temperatures above the norm for the time of year are experienced in low-lying areas and 

enclosed valleys. 

13

WIND 

Strong winds often associated with squalls and storms do occur (Dorrell, 1947) but destructive 

winds are not common. Direction and persistence of the wind (Text Maps 7a and 7b) are 

however of paramount importance. It can be seen that, with the southerly movement of the 

ITCZ from October to April the wind blows consistently from the north or, more often, the 

northeast. During this period the area is exposed to very dry winds blowing from the 

Sahara, the harmattan, often carrying a thick haze of wind-borne, conspicuously diamataceous, 

dust (Bigelstone, 1958; McKeown. 1958). Prom May, throughout the summer rains until 

September, the direction is reversed and the wind blows mainly across the area from the 

southwest. Again the Benue Valley is somewhat exceptional. The dry season wind tends to 

blow more directly from the north while the wet season wind is more westerly and even northwesterly 

orientated and commences earlier in March and finishes later in October, than the 

main part of the area. 

Once this wind pattern is appreciated, the rationale of the rainfall/temperature pattern 

falls into place. Local anticyclonic effects modify the generalised southwest direction of 

wet season wind . in West Africa particularly in the south of the project area. The generalised 

wind movements explain the near-diagonal oscillation of rain and temperature in the northern 

sector. In the southern sector, the more westerly/northwesterly wind creates a pattern in 

the wet season of up-wind exposure and down-wind rain shadow effects, fluctuating around the 

critical 900-1 000 mm (35 - 40 in) isohyets. The high temperatures in the dry season in the 

Benue Valley are probably due to low altitude and the effects of the land to the north 

blocking the northerly orientated wind. 

RADIATION 

Available data of relevance to the project area in the form of 'hours of bright sunlight' 

observations are restricted to Maiduguri, Bauchi, Ibi, Yola and Potiskum. Cochemé and 

Franquin (1967) also give useful data for the surrounding territories. 

Figure 3 shows the monthly variation in incoming radiation. The general picture is of radiation 

rising to a maximum in November - February and falling to a minimum in August. An 

interesting feature is the marked fall and recovery of the graph in the period February - 

April. In the far north this occurs in March and is probably associated with overcast conditions 

due to the meeting of the 'dust front' with the ITCZ (Hamilton and Archbold, 1945). 

In the southern stations it is a month later and probably associated with increased rain 

cloud and storm conditions as the ITCZ retreats southward. It should be noted that 

Maiduguri, which occupies an intermediate position, merely shows a flattening of the graph 

during this period. 

Included in Figure 3 are graphs for mean cloud cover which show a clear inverse relationship 

with the incoming radiation. 

HUMIDITY 

Humidity follows a simple relationship with the change of the seasons. Figure 4 shows the 

monthly change in saturation deficit reaching a peak in the pre-rains hot period in March - 

April and falling to a minimum in August in the mid-rainy season. It also follows a simple 

inverse daily relationship with temperature reaching minimum values at night and maximum ones 

at the height of the day. 

WATER BUDGET 

Unlike areas in the south of the country, radiation is not likely to be a limiting factor in 

plant growth and it is the availability of water that is of prime agricultural importance 

throughout the project area. Two approaches to the problem are possible; to consider the 

balance between precipitation gain and various forms of water loss largely calculated from 

climatic parameters, or to consider a level of precipitation based on past experience after 

which the 'rainy season' can be said to have 'safely' started or to have finished. 

14

Potential Evapotranspiration 

Discussion of the reason for using this parameter (PE) and the methodology employed in its 

calculation is beyond the scope of this report. Contributions of relevance to the survey 

area can be found in Cochemé and Pranquin (1967), Gamier (1960) and Ojo (1969). Despite 

cautionary canment from such authors as Sibbons (1962) and Stanhill (1965), calculations 

based on the method of Penman (1956) have been employed in deriving the generalised trends of 

PE shown in Figure 5. 

As stated, radiation data are sparse in the project area, as are also adequate measurements 

for the aerodynamic factor of the Penman equation. Cochemé and Franquin (1967) were able to 

employ some transformations of aviation wind measurements and Bawden and Tuley (1966) 

produced a set of figures for Yola using a conversion of Beaufort Scale recordings. Neither 

of these methods appears fully satisfactory, particularly as there is evidence (Hudson, 1965) 

that the importance of the aerodynamic factor is greatly increased under conditions similar 

to those found during winter in a large part of the project area. The calculated PE for the 

project area follows an expected pattern, rising to a maximum in March - April and falling to 

a minimum in August - September. Figure 5 shows how the graph flattens under more northerly, 

drier, conditions. 

Effective Rainfall 

The concept of 'effective rainfall' attempts to estimate the amount of rainfall available for 

plant growth, namely: 

Precipitation - (Evaporation + Runoff + Deep percolation). 

As shown in Figure 5, by combining PE and rainfall recordings a series of agriculturally useful 

parameters can be derived for those situations where run-off and deep percolation do not 

assume serious proportions. 

1. Humid Period: Rainfall > Evaporation 

2. Intermediate Period: Rainfall > 0.5 x Evaporation 

3. Moist period: 1+2 

Once these periods are defined in terms of duration, with starting and terminating dates, 

what is commonly termed the 'growing season' or 'rainy season' can also be defined, the terms 

being largely synonymous with 'moist period' (Cochemé and Franquin, 1967). 

The Wet Season 

Walter (1967) employs a more pragmatic approach in deriving this useful parameter. From his 

experience in West Africa he stipulates that the wet season in any calendar year is defined 

as falling between: 

1. the date after 50 mm (2 in) of accumulated rainfall has fallen; 

2. the date after which no more than 50 mm (2 in) remains to fall. 

His classification for the area in these terms, for the project area, is shown on Text Map 8. 

It is interesting to note the close relationship between his calculations and those of 

Cochemé and Franquin (1967) based on the calculation of PE. 

ECO -CLIMATIC TERMINOLOGY 

Following the above review of the major climatic parameters, the validity of the generalised 

climatic terms commonly used in West Africa and applicable to the project area requires 

examination. Three major zones and one intermediate zone are involved (cf Koppen, 1931): 

1. the Sahel Zone (approximating to a Koppen BSh climate); 

2. The Sudan Zone (intermediate between a Koppen BSh-Aw climate); 

3. The Sub-Sudan Zone; 

4. The Northern Guinea Zone (approximating to a Koppen Aw climate) 

15

Use of these terms has fallen into some disrepute, generally due to the looseness with which 

they have been applied (see comments under 'Vegetation') and to the view that they had proved 

so useful as a "blanket term' that investigations of the fundamental parameters involved had 

long been ignored. As originally conceived (Chevalier, 1900; Keay, 1953), the zones were 

established on the basis of an interrelated interpretation of rainfall records and vegetation/ 

land use observations. In the project area the Sahel, Sudan and Guinea Zones correspond respectively 

with the m.a.r. areas shown on Text Map 3: < 508 mm (20 in), 508-1 016 mm 

(20- 40 in), and > 1 016 (40 in). Figure 5 attempts to characterise the zones in terms of 

some of the major parameters involved. It can be seen that the characteristics of the zones 

are so dominated by the rainfall pattern that a classification based on this alone has considerable 

validity. The terms as defined in Figure 5 will therefore be used as climatic descriptions 

throughout the report. 

The Sub-Sudan Zone 

This term (Clayton, 1957) has been the cause of much discussion. It occupies an approximate 

rectangle bounded on the west by the Mandara range, on the east by 10° longitude, by the 

Benue Valley on the south and by the 890 mm (35 in) isohyet on the north- In this area the 

marked displacement of the 1 015 mm (40 in) isohyet is attributable to the westerly and 

northwesterly orientation of the rain-carrying winds resulting in a large rain shadow behind 

the Jos highlands and giving rise to an atypical broadening of the inter-isohyet belt 

between 1 015 m and 890 mm (40 and 35 in). The major significance lies in the fact that the 

rainfall change between these isohyets is highly sensitive in its effect on other environmental 

factors, a tension belt' in the sense of Fairbairn (1945). There is therefore an 

extremely marked orographic reaction to the westerly winds; open areas tend to be truly 

transitional, westerly faces tend to Northern Guinea conditions and easterly faces towards 

Sudan conditions. A good example is the belt of 1 015 mm (40 in) rainfall between the Biu 

Plateau and the sandstone hills to the south where the wind is forced upwards by the Mandara 

and Zummo Mountains. This effect dies out on the watershed, which forms the frontier with 

the Cameroon Republic. 

16

Omm 

Oin 

l-25mm 

(O-l-lin) 

25-50mm 

(l-2in) 

50-IO0mm 

(2-4in) 

I00-I50mm 

(4-6in) 

l50-200mm 

(6-8in) 

200-250mtn 

(8-1Oin) 

250-30Omm 

(I0-I2in) 

300-350mm 

(I2-I4in) 

350-400mm 

(I4-I6in) 

400-450mm 

(l6-1Sin) 

= = = 

D.O.S.(L.R.)3064H 


MEAN MONTHLY RAINFALL TEXT MAl 

Based on data provided by the Nigerian Meteorological Ï 

Drawn and photographed by Directorate of Overseas Survey 

Printed by Ordnance Ï

D.O.S.(L.R.)3064J. 


MEAN MONTHLY RAINFALL TEXT MAP 4b 



Printed by Ordnance Survey, 

't 

Omm 

Oin 

l-25mm 

(0 1-lin) 

25-50mm 

(l-2in) 

50-100mm 

(2-4in) 

100-ISOmm 

(4-6in) 

l50-200mm 

(6-8in) 

200-250mm 

(8-IOin) 

250-300mm 

(I0-I2in) 

300-350mm 

(I2-I4in) 

350-400mm 

(I4-I6in) 

400-450mm 

(l6-18in)

P 5-1 

O 2- 

D.O.S. 3099 A 

Distribution of rainfall for selected stations Figure I 

BAUCHI 1947-1964 Mean annual rainfall 1100mm (43 in) 

-iL 

IIJ II I I ! I I I I I I I II I ! I I 1 M II I I mill»» i i 10 15 20 25 30 35 40 45 50 53in 5 H—i—i—r 10 15 20 25 30 35 40 45 50 55in 

BIU 1940-1962 (Missing data for 3 years) Mean annual rainfall 1000mm (40 in) 

1 I I I I I I I I I I I I I I I I I I ! I I I I I I I I MUIIWU I I I I 

-|—i—i—r 

• 11111111111 I 

YOLA 1916-1963 (Missing data for 6 years) Mean annual rainfall 965mm (38 in) 

Hüll I mi 

POTISKUM 1936-1963 (Missing data for I year) Mean annual rainfall 810mm (30 in) 

lAJiWll i i i ii i Pi I i i 111 11 i i i 11 i i i i rrr i i 11 in m n i n i n Jl rn i i i 11 i M i i 

MAIDUGURI 1915-1963 (Missing data for 8 years) Mean annual rainfall 660mm (26 in) 

15- 

15- 

iJL 

10 15 20 25 30 35' 40 45 50 53in 5 10 15 20 25 30 35 40 45 50 55 in 

500 750 1000 1250 mm 

Annual rainfall 

21 

1—r

ABADAN 

290mm (I IS in) 

4 yrs 

310mm (125in) 

5 yrs 

" TTTT~r~r—-^"r""""T 

I ViT »'MI' I' » V O V D ' I f n J n I ) » s o M o 

DUMBOA 

940mm fl 

(37 in) 

9 yrs 

DARAZO * 

1000mm (40 in) 

6 yrs 

KWOJEFFA 

965mm (38 in) 

9 yrs 

SHANI* 

1040mm (41 in) 

7 yrs 

Rainfall dispersion diagrams - selected stations Figure 2 

Group'I < 500mm (20 in) 

GEIDAM YUSUFARI 

430mm (17 in) 455mm (18 in) 

10 yrs 15 yrs 

MONGONU * 

480mm (19 in) 

7 yrs 

| l f t l H | | t S 0 N 0 | I N I 11 | | » S 0 K D | I H » n | | I S 0 H 0 

Group 2 500-900mm (20-35 in) 

Group 3 900-l000mm (35-40 in) 

Group 4 > 1000mm (40 in) 

MUBI 

1040mm (41 in) 

II yrs 

IH1HJ|»SI)N0 | t H I H | | » S 0 K D | F B » H | | » S 0 N 0 

DOS. 3099 B 

POTISKUM 

810mm 

KALTUNGO' 

965mm (38 in) 

5 yrs 

BAUCHI 

1070mm 

(43 in 

12 yrs 

|i n » H | 

^ Highest recorded maximum B Mean O Lowest recorded minimum 

Distribution of mean monthly rainfall only 

23 

BASH AR* 

890mm (35 in) 

5 yrs 

BIU 

1000mm (40 in) 

22 yrs 

BAZZA * 

1120mm (44 in) 

6 yrs 

| F fi » n | | i s 0 N D 

mm 

r 500 

- 125 

r 500 

375 

375

20 l°-22-5°C 

(68 l°-72-5°F) 

22-6°-250°C 

(72-6°-770°F) 

25l°-27-5°C 

(77 l°-8l 5°F) 

27 6°-30 0°C 

(81 6°-860°F) 

30 l°-32 5°C 

(86 l°-90-5°F) 

D.O.S.(L.R.)3064K 


MEAN MONTHLY TEMPERATURE ("**+"•") TEXT M, 

Based on data provided by the Nigerian Meteorological 

Drawn and photographed by Directorate of Overseas Survc 

Printed by Ordnance

D.O.S.(L.R.)3064L 


MEAN MONTHLY TEMPERATURE ( MAX +" IN ) TEXT MAP 5b 



Printed by Ordnance Survey,

D.O.S.(L.R.)3064M 


MEAN MONTHLY MAXIMUM TEMPERATURE TEXT MAP 6a 



Printed by Ordnance Survey.

D.O.S.(L.R.)3064N 


MEAN MONTHLY MAXIMUM TEMPERATURE TEXT MAP 6b 




25I°-27S°C 

(77 l°-8l-5°F) 

27 6°-300°C 

(8l-6°-86 0°F) 

30l°-32-5°C 

(86 l°-90-5°F) 

32-6°-350°C 

(90-6°-950°F) 

35l°-37-5°C 

(95I°-99 5°F) 

376°-400°C 

(99-6°-l04 0°F) 

40l°-42-5°C 

(I04I°-I08 5°F)

MONTHLY ANALYSIS OF WIND DIRECTION TEXT MAP 7a 

The figures represent the number of occasions on which the wind 

direction was recorded, observations being taken thrice daily. 

D.O.S.(L.R.)3064O 


,/|\ APRIL 




D.O.S.(L.R.)3064P 


MONTHLY ANALYSIS OF WIND DIRECTION TEXT MAP 7b 




Mean daily hours of bright sunshine and mean daily cloud cover in Oktas Figure 3 

Oktas „»,.,.... Hours 

,„, Oktas 

BAUCHI 

10 IBI 

0- 

/ x-^f \ 

Approx annual total-3000 hrs 

-| 1 1 1 1 1 1 1 1 1 1 1— 

J F M A M J J A S O N D 

YOLA 

X 


" i — i — i — i — i — i — i — i — i — i — r 

MAINE SOROA 

% A 


\ 

\ 

V 

"I 1 1 1 1 1 1 1 1 1 1 r- 


* Based on limited data - see Volume S 

D.O.S. 3099 C 

- 9 

- 7 

- 6 - 

- 5 

10 -, 

- 9 - 

8 - 

7 - 

- 6 - 

S - 

^ 

>—x< 

«—*\ ' 

^x ' 


\_ 

1 1 1 1 1 1 1 1 1 1 1 r— 


MAIDUGURI ,. 

\ ' x. 

\_ 

N, 


"i—i—i—i—i—i—i—i—i—i—i—r 

10 - NGUIGMI 

9 - 

8 - 

7 - 

6 - 

5 - 

4 

V 


~ i i i i i i i i i i r 

37 


Cloud x x x Sunshine •---•--• 

- S 

- 0 

- 5 

- 0 

- 5

Mean saturation deficit (mb) at 0900 and at 1500 hours G.M.T. 

Millibars 

60-1 

50- 

40- 

30- 

20- 

10- 

Millibars 

60 

50- 

40- 

30- 

20- 

10- 

Millibars 

60 

50- 

40- 

30- 

20 

10- 

BAUCHI 

1500 hours 

0900 hours 

~l 1 1 1 \ 1 1 1 1 1 1 1 

J F M A M J J A S O N D Months 

YOLA 

1500 hours 

0900 hours 

~l 1 I 1 I 1 1 1 1 1 1 1 


MAIDUGURI 

1500 hours 

0900 hours 

"1 I 1 I I I I I 1 1 1 1 


D.O.S. 3099 D 38 

Figure 4

mm in 

300 12 -l Moist Period * 

Humid Period* ' 

1 1 - NORTHERN /^ 

GUINEA / \ 

250 10- 

9 - 

200 8 • 

o o 

300 12 

I I 

250 10 

9 

200 8 

7 

150 6 

5 

100 4 

3 

50 2 

I 

250 10 

9 

200 8 

7 

150 6 

5 

100 4 

3 

50 2 

7 - 

150 6 - 

100 4 - 

I 

**« / \ 

* / \ 

* 

* 

* 

/ 

/ 

\ 

\ 

* * / \ 

* * / \ 

* % / \ 

* >+ "' ° ° ° h V 

5 - /".," o o-V 

o / •••+•••- \ 

3 - 

50 2 - 

D.O.S. 3099 E 

SUDAN 

SAHEL 

M A M | 

*- -* 

Eco-climatic zones in the project area 

Formalised modal climatic parameters Figure 5 

Moist Period* 

M A M J A S O N D 

M j | 

Moist Period* 

+ + + + + Potential evapotranspiration 

Rainfall 

o o Temperature 

C °F 

T-40 

100 

--20 70 

60 

--10 50 

80 

20 7 ° 

60 

--10 50 

Annual rainfall > 1000mm ( 40in ) 

* Length of rainy season 150-170 days. 

Annual potential evapotranspiration 

End of April-Mid October 

I600-I800mm (63-71 in) 

Toul annual hours of bright sunlight 2700-3000 

Annual rainfall 500-1000mm (20-40in) 

* Length of rainy season 90-150 days. 

May-September 


I800-2000mm (71-80 in) 

Total annual hours of bright sunlight 3000-3300 

Annual rainfall < 500mm (20 in) 

• Length of rainy season 60-90 days. 

June- Mid September 


I800-2000mm (71-80 in) 

Total annual hours of bright sunlight 3000-3300 

" sensu Walter (1967) 

' sensu Cocheme and Franquin (1967) 

39

10° 12° 

14° 

i i 

12° 

10° 

LENGTH, START & END OF THE WET SEASON TEXT MAP 8 

SCALE 1:3,000,000 

MILES 0 25 50 75 100 MILES 

1st JULY 

+ + + + + + +- + + *•+ + + + + + + + +• + - 

S---. - 

,« OMacsena ., *"^. *N» * **X ^ V_ÜV _.•• 

N^W^ Giffhua (|,.!V>. ^T.,J,„> 

^^w>^y^S^p ~ / 

• / 

Hadejia „£ 

/ . . • • • 

•. 

^T 

s 

— ^ .> 

4 f 'S* /K 

,.•• / 

• ••' 

/ 

10° 

D.O.S.(L.R.)3064R 


tltungc >o" 

20th OCT 

180 

— — - — Main Road 

H 1 1- Railway 

*+++++++ International Boundary 

_Hawa\, 


j Song 

O Damboa 

1st MAY 

'140 

— #- 10th OCT 

160 

'120 

1st MAY Date of start of the wet season 

'60 Length of wet season in days 

_ _ __ 20th OCT Date of end of the wet season 

14° 

Based on Walter (1967). 


Printed by Ordnance Survey, 

12° 

10°

PHYSIOGRAPHY 

by 

M G Bawden 

The range of relief in the North East project area is shown on Map 1. This altitude 

information has been obtained from various sources. The Directorate of Overseas Surveys has 

published 1:50 000 scale maps (DOS series 430) with a contour interval of 15.24 m (50 ft) of 

the area east of Numan and south of Buni and Bama. West of Numan similar maps are being 

prepared by the Directorate and here, altitude data have been derived mainly from spot 

heights and road and rail survey traverses. These data have been related to the land system 

classification of the landscape, which is partly based on an interpretation of the relief 

from aerial photography. Parts of the area north of a line roughly from Bama west to Azare 

have been contoured during hydrological investigations; there is little variation in gross 

relief in this area. 

There has been no comprehensive account of the physiography of the area covered by the North 

East project since Falconer (1911) described the geology and geography of northern Nigeria. 

Grove (1957) described the main physiographic regions in Nigeria within the Benue catchment 

and Klinkenberg et al. (1963) have described the physiographic units within the Gongola 

Valley. Grove (1958), Grove and Pullan (1963) and Grove and Warren (1968) have described the 

major landforms in Nigeria within the Chad Basin and Pullan (1964) has described the landforms 

southwest of Lake Chad in more detail. Brief descriptions of other areas within the 

North East project area are contained in various Soil Survey Bulletins from the Institute for 

Agricultural Research, Samaru. 

The major relief units which occur in the North East project area are shown on Text Map 2. 

Because of the interrelation between the relief, the landform and the underlying rocks, most 

of the major relief units coincide with the land regions defined in Volume 3. Some major 

relief units contain more than one land region where the landforms within the major relief 

unit are formed on contrasting rock types, or are the product of more than one geomorphological 

process, or are the product of more than one cycle of erosion, or where one unit is 

sensibly contained by another at the smaller scale of the major relief unit map. 

The project area can be considered in two parts, north and south, separated by the boundary 

between Quaternary rocks of the Chad Formation and the older formations which lie to the 

south (see Text Map 9). Apart from the Basement plains which lie north of Mubi, and the 

Mandara Mountains on the extreme eastern border of the area, this twofold geological division 

roughly coincides with the divide between the northeasterly flowing rivers which drain to 

Lake Chad and the south and southwesterly flowing tributaries of the Benue (see Text Map 11). 

The northern part of the survey area consists almost entirely of extensive flat or very 

gently undulating plains descending gradually from 450 m (1 500 ft) in the south and west to 

275 m (900 ft) on the shores of Lake Chad. The very gentle relief of these plains, the 

vertical difference between the highest and lowest levels seldom exceeding 15 m (50 ft), continues 

as far south as Mubi in the upper reaches of the Yedseram river and is only broken 

along the frontier with the Cameroon Republic where the Mandara Mountains rise to over 

1 000 m (3 300 ft). The southern part is more varied. The centre of the area is dominated 

by the Gongola Valley which descends from 450 m (1 500 ft) to 150 m (500 ft) at the confluence 

with the Benue. The Valley is bounded on the west by the high ground of the Kerri 

Kerri Plateau and on the east by the Biu Plateau and the Gaanda Hills. Northwest of these 

Hills the gentle relief of the Uba Plains extends eastwards to the Mandara Mountains where 

the highest peaks reach over 1 200 m (4 000 ft). 

The Manga Plains, which lie in the northwest of the area, are composed of alluvial and 

aeolian sands overlying the Basement Complex and Younger Granite pediment to the hill range 

further north in the Niger Republic. The southern limit of these plains is marked by the 

Yobe River Complex which extends from Kano (west from the survey area) to Lake Chad in the 

northeast. This river complex comprises extensive ancient river courses, deltas and alluvial 

plains, many of which have been resorted by wind action and are now largely drift-covered. 

It also contains flooded remnants of longitudinal dunes of the Lantewa Dunefield as well as 

the present floodplain of the Yobe river and its tributaries. South of the Yobe River 

Complex a further series of aeolian sand plains extend southwards to the Benue watershed. 

These plains also contain largely drift-filled relics of a more extensive drainage system. 

43

The west and central portions of these plains contain extensive northeast-orientated longitudinal 

dunes are are part of the 'Ancient Erg of Hausaland' (Grove, 1958). The Lantewa 

Dunefield merges southwards into the Damaturu Plains which are a series of sand plains with 

very little relief. The cover of aeolian sand is thinner south of Damaturu and, along the 

southern border of these plains, clays and sandstones of the Chad Formation are exposed 

beneath the drift. Between Buni and Damboa the plains are underlain by rocks of the Basement 

Complex and by Cretaceous sediments. Between Potiskum and Azare aeolian drift sands similar 

to those of the Damaturu Plains overlie sandstones of the Kerri Kerri Formation and form the 

extensive Potiskum Plain. Apart from occasional flat-topped ironstone-capped hills this 

plain has very little variation in relief. 

In the northeast the longitudinal dunes of the Lantewa Dunefield are replaced by transverse 

northwest-orientated dunes of the Gudumbali Dunefield. These dunes rise as much as 15 m 

(50 ft) above the interdune areas. North of Mongonu some of the interdune areas contain 

extensive clay flats. The Lantewa and Gudumbali Dunefields are separated by a complex sand 

ridge called the Bama Ridge. This Ridge stands as much as 12 m (40 ft) above the surrounding 

plains and runs from east of Geidam, through Maiduguri and Bama, to the Cameroon frontier. 

It has also been mapped in the Niger and Chad Republics and marks an old shoreline of Lake 

Chad. A sand plain lying between the beach ridge and the dunes further east is interpreted 

as a former beach when Lake Chad was considerably larger than it is at the present time. 

East of the sand plains and dunefields the area is dominated by the Yedseram and El Beid 

rivers which flow north from the Mandara Mountains to Lake Chad. The upper reaches of the 

El Beid are in Cameroon Republic. In its upper reaches the Yedseram flows over the gently 

undulating Uba Plains, which descend gradually from over 600 to 300 m (2 000 - 1 000 ft) east 

of Damboa and are more typical of the Basement plains of the southern part of the project 

area. North of the boundary between the Basement rocks and the overlying Chad Formation the 

Bama Deltaic Complex extends as far north as Dikwa. This Complex consists of extensive clay 

and sandy plains with very little relief. South of Bama it contains both the present and 

older, more extensive, floodplains of the Yedseram river. North of Bama neither the Yedseram 

nor its major tributary, the Ngadda, reach Lake Chad. They disperse between the Bama Ridge 

and the present shoreline of the Lake over virtually flat plains. In the Bama Deltaic 

Complex these plains consist of a very complex association of deltaic deposits formed when 

Lake Chad extended to the Bama Ridge. East of Bama and north of Maiduguri, on the edge of 

the Gudumbali Dunefield, these deltaic deposits have partially buried relics of the longitudinal 

dunes. North and east of Dikwa this complex of deltaic plains gives way to extensive 

flat clay plains - known locally as 'firki'. These are the plains of the Chad Lagoonal 

Complex and they owe their form to clays deposited during lagoonal conditions of a more 

extensive Lake Chad. The present border of Lake Chad is marked by a series of undulating 

sand plains grouped as the Chad Lacustrine Plains. In the north these plains consist of a 

series of low sand ridges parallel to the present shoreline; further south small clay 

depressions occur within the sand plain and its border with the Chad Lagoonal Complex is 

marked by a small but distinct beach ridge. 

The Gongola and its tributaries form the major river system in the southern part of the 

project area. The Gongola rises on the Jos Plateau from where it flows northeast across the 

Bauchi Plains, west of the survey area, and through the Kerri Kerri Plateau as far as Nafada; 

it then swings abruptly south and flows through the main Gongola Valley to join the Benue 

opposite Numan. 

The Gongola Valley is cut mainly in Cretaceous sediments, although Basement rocks are exposed 

at Kaltungo and to the east of the Gongola between it and the Biu Plateau. The Valley contains 

flat and undulating plains descending gradually from 430 m (1 400 ft) southwest of 

Damaturu to 180 m (600 ft) north of Numan where they merge with the plains of the Benue 

Valley. The various plains are separated by hill ranges which in some places rise abruptly 

to over 300 m (1 000 ft) above the surrounding plains. These ranges are formed on both 

sandstones and Basement Complex rocks and there are many prominent single hills formed by 

volcanic plugs or cones. In the southern half of the Valley, where the Gongola cuts through 

folded Bima Sandstone, these hills form some of the most spectacular scenery in Nigeria. 

West of the Gongola Valley the Kerri Kerri Plateau forms extensive rolling upland plains 

between 300-600 m (1 000 - 2 000 ft), with occasional upstanding flat-topped ironstone-capped 

relic hills. North of the Gongola the Plateau drains to the Gongola itself; to the south 

most of the Plateau is drained south by the river Pai to the Benue. The Pai and its major 

tributaries have flat-floored incised valleys bounded in most places by steep sides rising to 

44

the more gentle Plateau slopes. In several places the escarpment, which bounds most of the 

Plateau, is dissected into a series of steep flat-topped ridges and flat-floored valleys. A 

similar dissected escarpment borders the Potiskum Plain southeast of Potiskum. 

North of the Hawal river the eastern border of the Gongola Valley is marked by steep hills 

and an escarpment rising between 150-300 m (500 - 1 000 ft) to the Biu Plateau. The Plateau 

consists of a series of gently sloping basaltic plains between 600 and 850 m (2 000 - 

2 800 ft) above sea level. 

North of Biu itself groups of steep conical hills, formed from extinct volcanoes, rise 

between 60 and 150 m (200-500 ft) above these plains. The escarpment continues south and 

east of Biu. South of Buni however it is less marked and only a low scarp marks the boundary 

with the Biu Plains. The Biu Plains consist of a series of flat or gently sloping plains 

descending gradually from 600 m (2 000 ft) adjacent to the Biu Plateau to 450 m (1 500 ft) on 

the border with the Uba Plains. 

The Uba Plains are drained by both the Hawal and the Yedseram river systems and in the south 

some areas are drained by the Kilunga which flows through the Gaanda Hills to the Benue. 

They consist of a series of gently undulating partially dissected plains between 600-300 m 

(2 000 - 1 000 ft) above sea level. The plains are underlain by rocks of the Basement 

Complex; their general uniformity is broken in several places by groups of spectacular 

inselbergs rising abruptly 150-300 m (500-1 000 ft) above the surrounding country. At Hong 

(between Gombi and Mubi) the highest peaks reach 1 300 m (4 300 ft). Most of these 

inselbergs are associated with Older Granites. 

South of the Hawal river the border between the Uba Plains and the Gongola Valley is marked 

by the Gaanda Hills which form a strongly dissected escarpment zone extending south from the 

Biu Plateau. Further east this hill range separates the Uba Plains from the lower-lying 

plains of the Benue Valley. The hills extend into the Cameroon Republic and, northeast of 

Song (at Zummo), they contain mountains with summits over 1 000 m (3 300 ft) which are 

similar to those in the Mandara range. 

The eastern part of the project area between Bama and Mubi is occupied by the Mandara 

Mountains. In the north this mountain range extends eastwards more than 50 km (30 mi) into 

the Cameroon Republic and outliers of these mountains form hills west of Maroua (see Text 

Map 1). Further south the mountains are confined to a narrower band. The frontier between 

Nigeria and the Cameroon Republic runs through the Mandara mountain range: only those hills 

and mountains in Nigeria are considered here. The highest summits rise steeply from the 

footslopes to over 1 200 m (4 000 ft). The footslopes themselves rise steadily from 450 m 

(1 500 ft) in the north adjacent to the Bama Deltaic Complex to 600 m (2 000 ft) at Mubi 

adjacent to the Uba Plains. They extend eastwards into the mountains where they occur in 

narrow valleys and are in some areas deeply eroded. The mountains themselves contain several 

areas of more gentle relief between the altitude of the footslopes and the summits. 

The south of the survey area lies in the Benue Valley and consists of a series of gently 

undulating plains rising from between 90-155 m (300-500 ft) along the Benue river itself to 

150-240 m (500-800 ft) adjacent to the Kerri Kerri Plateau, the Longuda Plateau and the 

Gaanda Hills. These plains are flanked by steep-sided sandstone hill ranges which follow the 

general east-west trend of the Valley and in places rise as much as 450 m (1 500 ft) above 

the plains. The Longuda Plateau lies between the Gongola Valley and the Benue Valley 700 m 

(2 300 ft) above sea level. It consists of undulating Basalt plains, similar to the Biu 

Plateau, bounded on all sides by an escarpment. It is however more dissected than the Biu 

Plateau. East of Yola sandstone hills have confined the width of the floodplain of the Benue 

to less than 500 m (550 yd). West of Yola, away from the hills the floodplain is very much 

wider and varies on the north bank alone between 3 and 12 km (2-7.5 mi). 

45

GEOLOGY 

by 

M G Bawden 

There are six major groups of rocks in the survey area each of which contains several 

different rock types. The distribution of these rock types is summarised on Text Map 9 and 

is shown in more detail, in association with the landform distribution, on Map 2. The 

geological succession is summarised in Table 1. 

TABLE 1 GEOLOGICAL SUCCESSION 

Group Rock type Formation Age 

VI 18 Recent alluvium Recent 

V 

IV 

III 

II 

I 

17 Ancient alluvium 

16 Lacustrine sands 

15 Lagoonal clays 

14 Deltaic sands and clays 

13 Beach sands and gravels 

12 Aeolian sands 

11 Consolidated sands and clays 

10 Pyroclastic rocks 

9 Basalt 

8 Continental sandstones with 

grits and clays 

7 Sandstone (continental facies) 

6 Clays and shales with thin 

limestones (marine facies) 

5 Sandstones and shales with 

thin limestones 

(transitional facies) 

4 Coarse feldspathic sandstones 

(continental facies) 

3 Granites 

2 Granites 

1 Metasediments, gneiss and 

migmatite 

46 

Chad Quaternary 

Kerri Kerri Tertiary 

Gombe and Gulani 

Fika, Pindinga, 

Numanha, Sekule, 

Jessu and Dukul 

Yolde and Gongila 

Bima and Yola 

Younger Granite s 

Older Granites 

Basement 

'Complex 

Tertiary - Recent 

Cretaceous 

Jurassic 

Lower Palaeozoic 

- Pre-Cambrian

10° 

^rr: 

Outside 

project area /,/ 

D.O.S. (LR) 3064U 


Structural Trend 

Geological Boundary 

Main Road 

Railway 

International Boundary. +• +• t- + + + 

SCALE 1:3,000,000 

25 50 75 100 MILES 

GEOLOGY TEXT MAP 9 

Group Rock Type Formation Age 

VI J I, 1 Mil! 18 Recent alluvium Recent 

V 

IV 

III 

II 

1MM1 

111! 

tök 

17 Ancient alluvium 

16 Lacustrine sands 

15 Lagoonal clays 

14 Deltaic sands and clays 

1 3 Beach sands and gravels 

12 Aeolian sands 

1 1 Consolidated sands and clays 

10 Pyroclastic rocks 

9 Basalt 

o Continental sandstones with 

grits and clays 

.mi,«.:" 1 !!' 

7 Sandstone (continental facies) 

Q Clays and shales with thin 

limestones (marine facies) 

e ","»',". Sandstones and shales with thin 

limestones (transitional facies) 

4 Coarse felspathic sandstones 

(continental facies) 

1 2 Granites •Hi 

Chad 

Kerri Kerri 

Gombe and Gulani 

Fika. Pindinga and Numanha, 

Sekufe. Jessu and Dukul 

Yolde and Gongila 

Bima and Yola 

Quaternary 

Tertiary-Recent 

Tertiary 

Cretaceous 

3 Granites Younger Granite Jurassic 

1 Metasediments, gneiss and 

migmatite 

Older Granite -, BaS(.menc 

J Complex 

Lower Palaeozoic - 

pre Cambrian 

12° East of Greenwich 14° 

Specialist information compiled by M. G. Bawden 


Printed by the Ordnance Survey 

7/7//J325/OS 

10°

The information shown on these maps and in Table 1 has been obtained from several sources. 

The earliest overall description of the geology of northern Nigeria was made by Falconer 

(1911). Within the project area detailed mapping by the Geological Survey has been confined 

to the Gongola Valley and its immediate surroundings (Carter et al 1963). Du Preez (1949) 

described the geology of the Biu Division and Jones (1959a, b, and c; 1960) described the 

sediments in the area of the Benue Valley south of the Gaanda Hills, but published no maps. 

More recently Dousse (1969) has mapped the sandstones underlying the Potiskum Plain and 

the Kerri Kerri Plateau and Dessauvagie (1969) has described the geology of the extreme 

southwest of the project area between Bashar and the Benue river. Most of the geological 

investigations of the Chad Formation have been related to the hydrogeology of the 

Chad Basin and borehole records provide a considerable amount of information on the 

stratigraphy of the Nigerian portion of the Chad Basin and the sequence of pre-Quaternary 

rocks which underlie the Chad strata. The 1:2 000 000 scale geological map of Nigeria (1964) 

covers all the North East project area and there are maps and reports for Cameroon and Niger 

covering their common frontiers with Nigeria. This information, together with airphoto 

interpretation and ground observations made during the present investigation and observations 

recorded during several soil investigations, has been combined to provide a regional picture 

of the geology of the project area. 

ROCK TYPES 

Group I. Igneous and Metamorphic Rocks, Mainly of the Basement Complex 

The Basement Complex includes the oldest known rocks in Nigeria. It consists of scattered 

remnants of highly metamorphosed sedimentary rocks (type 1) and diverse, predominantly 

granitic, plutonic masses collectively known as the Older Granites (type 2). In the project 

area the Basement Complex is composed mainly of gneisses, migmatites and granites. These 

Basement rocks have been described and mapped in the Gongola Valley and south of the 

Benue river by Carter et al. (1963) and in the Jos Plateau area adjacent to the Bauchi Plains 

(west of the project area) by MacLeod et al. (1966). The occurrences over the remainder of 

the North East project area are only sparsely documented, but the Basement throughout 

northern Nigeria shows considerable uniformity in its gross characteristics and the descriptions 

for areas which have been studied systematically can, in general terms, be extended to 

cover the whole area with reasonable confidence. 

Type 1. Metasediments, gneiss and migmatite The metasediments of the Basement Complex 

are a group of highly metamorphosed sedimentary rocks consisting mainly of gneisses and 

migmatites. Areas of schist and quartzite also occur and small occurrences of amphibolite, 

gabbro and pegmatite are widely distributed. These metasediments have only a scattered distribution 

in the Gongola Valley; airphoto evidence suggests that they are more extensively 

developed in the Uba Plains, but there has been no systematic mapping in this area. 

Type 2. Granites (Older Granites) The oldest rocks of the Basement Complex have 

been subjected to at least two major orogenic cycles (Oyawoye, 1964). Rocks of the Older 

Granites suite were formed during the second cycle, which extended from late Pre-Cambrian to 

lower Palaeozoic (Jacobson et ai.,1963). The Older Granites show all stages of granitisation 

and magmatic activity. They have a considerable range in structure, texture and mineralogy 

and their contact relationships with the metasediments are very variable. In the 

Gongola Valley, where the Older Granites have been studied in detail by Carter et al. (1963), 

the most extensive rocks are equigranular and coarse porphyritic granites. They are 

characteristically rich in potash and range in composition from granite to granodiorite. 

Similar rocks have been described from the Mandara Mountains in Cameroon (Gazel et al., 

(1956; Koch, 1959) and the Mandara Mountains in Nigeria are believed to consist largely of 

Older Granites (Nigeria Geol. Surv., 1964). The distribution of Older Granites between the 

Gongola Valley and the Mandara Mountains, where they form the more massive inselbergs in the 

Gaanda Hills and on the Uba Plains, is based mainly on airphoto interpretation done during 

the present investigations. 

Type 3. Granites (Younger Granites) West of the project area granitic massifs are 

developed over a wide area in the Jos Plateau region (Jacobson et al., 1958). These massifs 

are composed of a wide variety of medium to coarse-grained granites together with syenite, 

gabbro and rhyolite. They are discordantly intruded into the Basement Complex with sharply 

defined contacts which cut across these older rocks. They are of mid-Jurassic age 

(Jacobson et al., 1963) and are collectively termed Younger Granites. Granites which can 

definitely be included in this group outcrop only in the extreme northwest of the project 

area near Matsena. In the Gongola Valley Carter et al. (1963) describe a group of granites, 

porphyries and lavas which intrude the Older Granites west of the confluence of the Hawal 

49

and the Gongola. They do not however contain the suite of rocks or the structures characteristic 

of the Younger Granites elsewhere. They are grouped with the Younger Granites 

simply because they are granitic and are demonstrably younger than the Older Granites. 

Group II. Cretaceous Sedimentary Rocks 

Cretaceous sedimentary rocks lie unconformably on the Basement Complex in both the Benue and 

Gongola Valleys. They are believed to have been deposited in a rift valley which approximately 

followed the present alignment of the two valleys (Wright, 1968). Similar sediments 

overlie the Basement Complex northeast of the Biu Plateau, and have been recorded in boreholes 

as far north as Maiduguri under the Chad Formation. The details of the succession are 

understood better in some areas than in others. The Gongola Valley and parts of the Benue 

Valley have been mapped and described in detail (Carter et al., 1963). The western part of 

the Benue Valley has been mapped photogeologically by Dessauvagie (1969) and Jones (1959 a, 

b, and c; 1960) has described the sediments in the Benue Valley east of the Gongola river. 

No detailed mapping has been done in the area northeast of the Biu Plateau and the information 

presented here is derived largely from soil investigations by Carroll and Klinkenberg 

(personal communications). 

The oldest Cretaceous sediments are continental in character and consist of coarse-grained 

false-bedded feldspathic sandstones (type 4), of which the Bima Sandstone is the most important 

and the most extensive member. The younger sediments are more complex in character; 

in general the rocks consist of sandstones and shales (type 5), which are transitional in 

character between the continental conditions and the subsequent marine conditions, overlain 

by marine clays, shales and limestones (type 6). These marine strata are overlain by a 

further series of continental deposits (type 7) consisting of estuarine and deltaic sandstones 

and silt stones of which the Gombe Sandstone is the most extensive. 

The Cretaceous sediments were laid down in the Benue and Chad Basins. These were separated 

by a ridge of Basement Complex rocks on which the sediments are less thick than elsewhere. 

This ridge - known as the Zambuk Ridge - now lies on a line roughly from the Biu Plateau 

through Gombe to Kaltungo along which inliers of Basement rocks are exposed (see Text Map 9 

and Figure 6a). 

Because of this division into two separate areas of deposition and the changes from initial 

continental conditions to marine conditions and back to continental conditions, the sequence 

of Cretaceous strata is different in different parts of the survey area and rocks of very 

different composition may be the same age. 

Type 4. "Coarse feldspathic sandstones.icontinental faciesj(Bima and Yola),The Bima 

Sandstone is the oldest and most extensive of the Cretaceous sediments. It consists of 

massive coarse false-bedded sandstones resting unconformably on rocks of the Basement Complex. 

It was derived largely from the erosion of these rocks. The lower beds are invariably feldspathic 

but the higher beds generally contain less feldspar. The false bedding and diverse 

lithology of the Bima Sandstone indicate that it accumulated under widely varying continental 

conditions. Evidence of fluviatile and deltaic conditions is given by many cross-bedding 

structures, and the massive white and purple clays which are included within the sandstones 

are probably of lacustrine origin. The Bima Sandstone is thickest in the Lamurde anticline, 

in the Benue Valley. The bottom of the succession is not exposed but its total thickness is 

probably more than 3 000 m (9 800 ft). East of the Song-Yola road sandstones which are 

indistinguishable from the Bima Sandstone occur throughout the sequence and show that in this 

area continental conditions of deposition continued throughout the Cretaceous. Jones (1959 

(c)) defined these Bima-type sandstones, which are comparable in age with the transitional 

and marine sediments, as Yola Sandstone. 

Type 5. Sandstones and shales with thin limestones, transitional facies (Yolde and 

Gongila) Over most of the area in the Benue Valley, apart from the extreme east beyond the 

Song-Yola road, and in the Gongola Valley, the continental conditions of the Bima Sandstone 

were followed by marine conditions. The sediments which mark the change consist of a very 

variable sequence of sandstones and shales with thin limestones defined as the Yolde Formation. 

North of the Zambuk Ridge a similar transitional phase is marked by 450 m (1 480 ft) 

of limestones and shales with some sandstones defined as the Gongila Formation. Small areas 

of similar transitional sediments occur in the Damaturu Plain east of Damboa and further 

south in the Uba Plains but they have not been investigated in any detail. 

50

Type 6. Clays and sandstones with thin limestones, marine facies (Pika, 

Pindinga, Numanha, Sekule Jessu and Dukul) A conformable sequence of about l ooo m 

(3 300 ft.) of marine strata overlies the transitional Yolde Formation south of the Zambuk 

Ridge. These marine strata are assigned to four Formations (Carter et al., 1963): 

4. Numanha Shales - shales with occasional bands of sandstone, 

nodular mudstone and limestone; 

3. Sekule Formation - shales with thin bands of limestone; 

2. Jessu Formation - alternating sequence of shales and sandy mudstones 

with thin sandstone horizons; 

1. Dukul Formation - shales and thin limestones. 

Further north in the Gongola Valley, in the area of the Zambuk Ridge, the marine strata 

overlying the Yolde Formation consists of 200 m i(650 ft) 1 of shales with thin limestones at 

the base, which have been defined as the Pindinga Formation. East of Nafada the change from 

the transitional conditions of the Gongila Formation to the marine conditions represented by 

the Pindinga Formation was gradual and irregular and the two Formations cannot be clearly 

differentiated. North of Nafada the marine deposits are blue-black shales, occasionally 

gypsiferous and containing one or two impersistent limestones. These are defined as the 

Fika Shales; their total thickness is not known but a borehole at Damagum proved a minimum 

of 430 m (1 400 ft). 

Type 7. Sandstone, continental facies (Gombe and Gulani) North of the line of the 

Zambuk Ridge the marine strata of rock type 6 are overlain by 300 m (1 000 ft.) of estuarine 

and deltaic sandstones, siltstones, shales and ironstones. These were probably deposited in 

a basin which lay north of the Zambuk Ridge in the late Cretaceous. These strata are defined 

as the Gombe Sandstone (Carter et al., 1963) and are largely composed of siltstones or 

flaggy sandstones. They are soft and light grey when fresh, but on exposure give rise to 

dark red, flaggy debris which characteristically mantles the Gombe Hills. In the east of 

the Gongola Valley the marine Pindinga shales are overlain by at least 60 m (200 ft), of 

cross-bedded massive fine- and medium-grained sandstones which also represent a change to 

estuarine conditions. These rocks are probably the same age as the Gombe Sandstone but there 

is no evidence to suggest that they were deposited in the same basin. The fourfold sequence 

of marine strata in the south of the Gongola Valley and in the Benue Valley is followed by 

the Lamja Sandstone. This Formation outcrops over only a small area below the basalt on the 

eastern margin of the Longuda Plateau. It consists of fine-grained sandstones with thin, in 

some places carbonaceous shales; thin coal seams are exposed at two localities. Although 

exposed over a very small area the Sandstone represents a change to similar continental conditions 

i._ at least part of the 3enue Basin as that which occurred further north in the 

region of the Zambuk Ridge and in the Chad Basin. 

Group III. Tertiary Continental Sandstones 

Type 8. Continental sandstones with grits and clays (Kerri Kerri) The Tertiary 

sedimentary rocks within the project area consist of a sequence of flat-lying continental 

grits, sandstones and clays known as the Kerri Kerri Formation. They underlie the Kerri 

Kerri Plateau and the Potiskum Plain', to the north. A small outlier occurs in the Korode 

Escarpment northeast of the Biu Plains. 

The Kerri Kerri Formation was deposited on an irregular post-Cretaceous land surface under a 

wide range of continental conditions. West of the Kerri Kerri Plateau it lies unconformably 

on the Basement Complex. In the east and south it lies unconformably on Cretaceous sediments; 

the westerly extension of these sediments underneath the Kerri Kerri Formation is not known. 

Lacustrine and deltaic sediments are the most frequently occurring strata in the Kerri Kerri 

Formation. There are similarities in lithology and sedimentary structures between the Kerri 

Kerri Sandstone and the Bima Sandstone, though the latter is characterised by the feldspathic 

content of its sediments and a very much coarser grade. 

Information from drilling indicates that the total thickness of the Kerri Kerri Formation is 

not more than 300 m (1 000 ft) and that it does not extend far to the east and north below 

the Chad Formation (Dousse, 1969). 

51

en 

to 

DOS. 3099 F 

Geological Section Figure 6a 

4000' -, 

2000' 

Sea level 

N 70' E 

N IIO'W N 110° E 

Gongoli River Bima Hill 

Hawal River Askira Tedseram River 

T^>-< + +> + + + + ++ v + + + + +v + +"

en 

2000' 

S«a l«v«l . 

N45°E 

Geological Sections Figure 6b 

Buratai Hawal River Halduguri 

Basalt 

+ + + + + + + 

+ + + + Basement Complex + + + + + 

+ + + + + + + ++ + + + ++ + + + + + + 

+ ++ + + + + +++++ + 

D.O.5. 3099 G 

4000' 

2000' 

North 

Section north-east from the Biu Plateau (Buratai) to Lake Chad 

Hawal River - Garkida Song Loko River 

^Basalt B«..i. _-i^\ N AA v u •> 

^^^^^ Basalt "+"""+i + r^- S \ Yolde f* 

^ ^ > j. '4. + +T + + + + ' + +" + [V ___-—

spm,^ 

PLATE 1/1 Song. View from basalt hill across farmland 

with Adansonia digitata and Acacia albida. 

Typical inselbergs in the background. 

PLATE 1/2 Biu Plateau. General view northwards from Tilla 

Lake with cones and craters in the far distance. 

54

PLATE 1/3 The Kadi Escarpment. 

PLATE 1/4 Near Pindinga. Exposure of Pindinga shale in 

river bank in predominantly Gombe Sandstone, 

Land System IIb7, the Gombe Plains. 

55

Group IV. Tertiary to Recent Volcanic Rocks 

Volcanic rocks are widely distributed in the southern part of the survey area. They occur 

as volcanic plugs in the Benue Valley and in the southern part of the Gongola Valley, and as 

basaltic lavas forming the Biu and Longuda Plateaux and other smaller complex lava flows of 

which the Song Volcanic Complex is the largest. The age of this volcanic epoch has not been 

precisely determined but it seems likely that it extended from the mid-Tertiary to Recent 

(Carter et al., 1963). 

The distribution of the volcanic plugs is irregular and they do not appear to be associated 

with any tectonic lines. They cut all formations of the Cretaceous succession but have not 

been seen to intrude the Kerri Kerri Formation or later rocks. 

Type 9. Basalt The Biu Plateau and the Biu Plains are underlain by extensive flows of 

olivine basalt. These basalt flows were extruded spasmodically over a considerable period 

of time and the total thickness is made up of several flows. On the west of the Biu Plateau 

the total thickness is less than 30 m (100 ft ) (Carter et al., 1963), but further east 

du Preez (1949) estimated a total thickness 'in the order of 300 m (1 000 ft)' . The basalts 

are fine-grained, dense, olivine-bearing rocks. The various flows show little variation in 

appearance or composition. There is no satisfactory evidence to show their mode of eruption; 

no parent vents have been identified and there is no indication that they were 

extruded from fissures. The lavas were very fluid and thin flows extend over wide areas. 

The Longuda Plateau is more dissected than the Biu Plateau and is much smaller, but it is 

capped with similar dominantly fine-grained olivine basalts. They are flat-lying and attain 

their maximum development in the eastern part of the plateau where they are 300 m (1 000 ft ) 

thick (Carter et al., 1963). In many localities around the escarpment edge to the plateau 

individual flows can be readily identified; the variation in thickness of these flows seems 

to be controlled largely by the pre-basalt topography. Like the Biu basalts, there is no 

evidence of either the mode of eruption or the precise age of the Longuda lavas. No parent 

vents or fissures have been located and there is no evidence to suggest that the Biu and 

Longuda basalts were derived from a common source. 

Similar but smaller areas of volcanic rocks, consisting mainly of olivine basalt flows, with 

small quantities of pyroclastic rocks, occur immediately to the south of the Biu Plateau at 

Garkida and further south in the vicinity of Song and Kuma. They have also been recorded 

(Nigeria Geol. Surv., 1964) in small areas within the Mandara Mountains, but their distribution 

has not been mapped in detail and they are omitted from the maps accompanying this 

account. 

Pine-grained olivine basalts also form the majority of the volcanic plugs which are widespread 

in the south of the Gongola Valley and in the Benue Valley. More than 300 have been 

mapped (Carter et al., 1963) varying in size from small mounds a few meters high to towering 

conical hills rising more than 300 m (1 000 ft ) above their surroundings. They are most 

numerous south and west of Kaltungo where one of the best known peaks formed by a volcanic 

plug is Tangale peak, the summit of which reaches 1 300 m (4 260 ft ), some 600 m (2 000 ft ) 

above the surrounding Bima Sandstone. 

Type 10. Pyroclastic rocks There are several well preserved volcanic vents and 

craters on the Biu Plateau which are composed of a variety of pyroclastic rocks (du Preez, 

1949). The cones to the west of the Biu-Damaturu road are composed of decomposed scoriae, 

fragments of ropy lava, bombs, tuffs and agglomerates which contain boulders of granitegneiss. 

Agglomeratie tuffs form aprons around the cones west of Meringa and agglomerates 

consisting chiefly of lava bombs form many cliffs and crags. Ultra-basic nodules are an 

important component of the agglomerates in some areas. Small basalt lava flows and mud 

flows occur with these pyroclastic rocks in several places on the Plateau. 

Similar but much less extensive areas of pyroclastic rocks occur in the Song Volcanic 

Complex but have not been mapped. 

Group V. Quaternary Sediments of the Chad Formation 

Quaternary rocks within the project area are mapped by the Nigeria Geological Survey (1964) 

as one formation - the Chad Formation. As mapped, the Formation includes a wide range of 

consolidated lacustrine and fluviatile sands and clays overlain by unconsolidated largely 

wind-blown sands and a wide range of alluvial, deltaic and lagoonal sediments. The consolidated 

sediments have been described by Barber (1965). Higgins et al. (1960) and Pullan 

(1964) have described the unconsolidated superficial deposits. These superficial deposits 

56

are closely related to the present landforms and to the recent evolution of the Chad Basin; 

as they are therefore discussed in more detail below under 'Geomorphology' , their lithological 

characteristics are only briefly described here. 

Type 11. Consolidated sands and clays (Chad) Consolidated sediments of the Chad 

Formation are exposed beneath thin superficial deposits southwest of Maiduguri and south and 

west of Damaturu. In the latter area they overlap Cretaceous rocks in the Gongola Valley 

and outliers of the oldest Chad strata have been recorded by Carter et al. (1963) as far 

south as Nafada. North of the Potiskum Plain Chad strata overlap the Kerri Kerri Sandstone 

and further west they overlap the Basement rocks underlying the Bauchi Plains. The boundary 

with these older rocks has been mapped by Schroeder (Nigeria Geological Survey, unpublished 

map 1969). 

Elsewhere in northeast Nigeria the consolidated sediments of the Chad Formation are covered 

by more recent unconsolidated deposits; there are no exposures of the consolidated sediments 

and their distribution and lithology is known only from the evidence of boreholes. 

These Chad strata consist of a complex series of lacustrine and fluviatile clays and sands. 

They show considerable lateral variation both in thickness and in composition, but a general 

threefold .sequence of a thick clay series overlain and underlain by somewhat clayey 

arenaceous series has been recognised over a wide area (Barber, 1965). These strata have 

very gentle regional dip northeast below Lake Chad, but in any one locality they are more or 

less horizontal. In the Gongola Valley the Chad sediments vary in thickness from a few 

meters to 120 m (400 ft ). Near Maiduguri they are 550 m (1 800 ft ) thick; further east 

they increase to about 600 m (2 000 ft ). 

Type 12. Aeolian sands (Chad) North of a line from Azare through Maiduguri to 

Mongonu the near-horizontal strata of the Chad Formation are overlain by unconsolidated predominantly 

aeolian (wind-blown) sands. The sands form extensive hummocky plains in which are 

developed two main groups of sand dunes. These sand plains and dunefields are part of the 

ancient erg of Hausaland (Grove, 1958) and are related to the former extent of desert conditions. 

North and east of Maiduguri the sands are partially buried by more recent deltaic and 

lagoonal deposits (rock types 14 and 15). The origin of these sands is not clearly understood. 

Pullan (1964) has suggested a fluvial origin with subsequent wind action at two 

separate stages forming the two main groups of dunes. 

Type 13. Beach sands and gravels (Chad) There are two groups of sands and gravels 

which form distinct complex ridges and are interpreted as former beach ridges of Lake Chad 

(Grove and Pullan, 1963). The larger and older is the Bama Ridge which extends from east of 

Geidam, through Maiduguri and Bama to the Cameroon frontier. Du Preez (1949) and Barber and 

Jones (1960) record a range in composition from coarse sand and gravel through grit and fine 

sands to silts. Pullan (1969) showed that fine to medium sands predominate and suggested 

that the coarse gravels are confined to the core of the ridge. A smaller more recent ridge, 

composed mainly of rounded sands and known as the Ngelewa Ridge, runs from west of the 

El Beid river through Gambaru to Mongonu. 

Type 14. Deltaic sands and clays (Chad) East of Maiduguri aeolian sands of type 12 are 

overlain by an extensive very variable succession of sands and clays. These were laid down 

in a series of successive deltas formed by rivers flowing north from the Mandara Mountains. 

The deposits occur in both ancient, now largely abandoned, deltas associated with previous 

courses of the river system which flowed into Lake Chad when it extended to the Bama Ridge, 

and in smaller more recent deltas formed by the present rivers which flow through the Bama 

Ridge but do not reach the Lake. 

Type 15. Lagoonal clays (Chad) North and east of Dikwa the deltaic deposits of type 

14 pass laterally into greyish brown and black clays, known locally as 'firki' . In some 

places the clays are laminated and have the characteristics of a shale. Calcium carbonate 

concretions are abundant in the brown clays; the darker clays have a strong polygonal macrostructure 

and are believed to contain a high percentage of montmorillonite (Pullan, 1964). 

These clays were deposited under lagoonal conditions associated with the previous greater 

extent of Lake Chad. In some areas deposition seems to be continuing at the present time, 

mainly due to river flooding (Klinkenberg, personal communication). 

Type 16. Lacustrine sands (Chad) The present shore of Lake Chad is bounded by uniform 

medium to fine sands. In the north they form a complex series of parallel beach dunes; 

further south the predominantly fine aeolian sands are associated with alluvial silts, loams 

and clays. 

57

Type 17. Ancient alluvium (Chad) In the north of the project area both the sand 

plains and the dunefields are overlain by alluvial sands and clays related to former courses 

of the Yobe river and its tributaries. In several areas these sands and clays have been 

partially re-sorted by wind action and are now associated with, or overlain by, aeolian 

sands from the adjacent sand plains and dunefields. South of the Bama Ridge alluvial sands 

and clays from the Yedseram form extensive spill plains and terraces over rocks of the Chad 

Formation and the Basement Complex. East of Bama, on the Cameroon frontier, alluvial clays 

form spill plains associated with previous more extensive phases of the El Beid river system. 

Some areas underlain by these ancient alluvial deposits are subject to occasional flooding 

at the present time and therefore also contain recent alluvium. 

Ancient alluvial deposits are far less extensive in the southern part of the project area. 

Small areas of alluvial sands border the present floodplain of tributaries of the Gangola 

south of Shellan, and there are areas of older alluvial deposits bordering the present floodplains 

of the Loko river south of Song. In the Benue Valley Carter et al. (1963) mapped an 

extensive series of piedmont deposits consisting of ancient alluvial sands and clays which 

they grouped together as Benue Valley Alluvium. Klinkenberg (1967) showed that some of 

these sands and clays were developed in situ from Cretaceous sediments and that older 

alluvial deposits associated with the Benue are more limited in extent (see Map 2). 

Group VI. Recent Alluvium 

Type 18. Recent alluvium This alluvium occurs along most of the water courses in the 

project area. It ranges in extent from thin discontinuous sands occurring in the smallest 

streams to thick broad alluvial sands and backswamp. clays of the Gongola, Benue, Yedseram 

and Yobe rivers. 

Structure 

The Older Granites and associated granite gneisses of the Basement Complex have a well 

developed and generally widely spaced pattern of rectangular jointing. In general joints are 

better developed in these granitic rocks and in the quartzites than in the other metasediments. 

As a group the metasediments present a remarkably uniform series of strongly foliated 

rocks; in detail the structures are very complex and there is evidence that they have been 

folded more than once. 

The major structural trends in northeast Nigeria have been determined by earth movements 

immediately preceding and following the deposition of the Cretaceous sediments. The structural 

pattern within the Cretaceous rocks is dominated by a series of long, narrow and 

relatively simple folds (see Text Map 9). The Tertiary and younger strata are virtually 

flat-lying and, although downwarped towards the northeast, are unaffected by folding or 

faulting. The main structures in the Gongola Valley are summarised in Figure 6a, which also 

shows the relations of the other rock types on either side of the Valley. Figure 6b summarises 

the relation of the various rock types northeast and south of the Biu Plateau. 

Various workers (e.g. Pugh and King, 1952) have suggested that the Cretaceous sediments in the 

Gongola and Benue Valleys were deposited in troughs resulting from rift faulting of the 

Basement rocks. This early Cretaceous rift faulting was associated with the separation of 

South America from Africa during the breakup of Gondwanaland (King, 1950). Rift faulting was 

supported by Cratchley and Jones (1965) who suggested that the main faults are buried by the 

Cretaceous sediments. 

The main late Cretaceous folds in the Gongola Valley are the Kaltungo and Bima anticlinoriums 

and the Gulani synclines. The Kaltungo anticlinorium is the largest structural unit and 

embraces complicated folds between the Kaltungo Basement inlier and the Basement south of the 

Biu Plateau. At Kaltungo the strata form a broad northeast trending anticlinal structure 

with the Basement inlier at its core. East of the inlier this structure divides northeastwards 

and passes into a series of separate anticlines and synclines. These folds are 

characteristically asymmetrical, showing steeper dips along their northern limbs. The main 

component of the Bima anticlinorium, the Bima anticline, plunges west near Zambuk. The 

inlier near Gombe represents part of this fold repeated by faulting (Figure 6a). Later subsidiary 

folds with a north-south trend are superimposed on the Bima anticline. North of the 

Bima anticlinorium the fold pattern is predominantly north-south and consists of a series of 

comparatively small basin-shaped folds which owe their prominence to the resistance of the 

Gulani Sandstone. North and east of Nafada the folds have a southeast trend. 

58

The Cretaceous rocks south of Damboa are not well exposed and their structures have not been 

investigated. However, airphoto evidence suggests that the general east-west strike is continued. 

No major fold areas have been identified and, compared with the scale of folding in 

the Gongola Valley, the strata seem to be only gently folded. 

The Benue Valley is characterised by long asymetrical folds of which the Lamurde anticline is 

the most important and extends for nearly 95 km (60 mi) southwest from the Longuda Plateau. 

It is flanked on the north by the Dadiya syncline and on the south by the Benue syncline 

which is largely masked by alluvial deposits from the Benue. The general northeast trend of 

the Lamurde anticline is continued by similar but shorter folds south of Bashar 

(Dessauvagie, 1969) and east of the Gongola between Yola and Song. 

There is evidence that the earth movements responsible for folding the Cretaceous sediments 

to some extent preceded the deposition of the youngest strata. The gentle folding of the 

Gombe Sandstone contrasts with the strong folds imposed on the older rocks and, although no 

unconformity has been detected between the Gombe Sandstone and the underlying formations, the 

Gombe Sandstone seems to post-date the main period of folding in the region. 

Faulting, which mainly took place after the folding, has affected all the Cretaceous rocks in 

the Gongola Valley. Two classes of faults have been recognised (Carter et al., 1963): strike 

faults, which are best developed in the vicinity of the Zambuk Ridge, and tension faults 

which occur at the margins with the Basement. At least two periods of faulting have been 

recognised; early faults with easterly trends are truncated or offset by later northerly 

trending fractures. Faults are less common in the Benue Valley and the major folds are 

largely undisturbed by faulting. 

The structural pattern in the Cretaceous rocks shows that the major compressional stresses 

operated from the north and south whilst subsidiary stresses took place at right angles to 

this. Wright (1968) suggested that the folds were a result of compression which followed 

the tensional rift faulting. "When Africa and South America finally separated, the southern 

half of Africa tended to swing back, so that the hitherto stretched Benue trough region was 

transformed into a minor compressional belt, folding the sediments with it' . 

59

GEOMORPHOLOGY 

by 

M G Bawden 

Over most of northeast Nigeria there is a close relation between the landforms and the underlying 

rocks observable both at the regional scale of the major relief units (Text Map 2) and 

at the more detailed larger scale. Indeed, it is this close relation between the shape of 

the land, the rock types and the soils derived from those rocks which makes possible the 

extensive use of aerial photographs in mapping the land resources. As has already been mentioned 

this close correlation between relief, rock type and the soils derived from them is 

also the basis for the land system classification which is described in Volume 3 of this 

study. 

The landform of the major relief units has been briefly described under Physiography and 

the rock types have been described under Geology. The purpose of this Geomorphology section 

is twofold; first to describe the landforms and their association with the main rock types 

and second to suggest the probable sequence of development of the present landscape. 

The distribution of the landforms and the rock types with which they are associated is shown 

on Map 2. Because associations of landforms are closely related to the 6 major groups of 

rock types, the landforms are described under the same group headings as those used in the 

Geology chapter. The soils are described under similar headings for the same reason. 

Landforms Developed on Rocks of Group I: Igneous and Metamorphic Rocks, mainly 

of the Basement Complex 

The general pattern of landforms developed on Basement Complex rocks is simple. The pattern 

is more complex in the hilly areas than in the plains, but in both the number of different 

landforms is small. In detail the wide variety in lithology of the Basement rocks results in 

a considerable variation in their resistance to erosion, and there are many minor changes in 

landscape throughout the Basement plains which can be directly related to this variation in 

lithology. 

The migmatites and gneisses (rock type 1) generally underlie more or less dissected undulating 

or gently undulating to flat plains. The relief is fairly uniform with only occasional 

hills rising above the level of the gently sloping interfluves. Upstanding areas which do 

occur in these plains are generally isolated rocky hills (inselbergs) or low elongated 

ranges often with a serrated outline. The orientation of these low ranges usually follows 

quartzite ridges, dykes or fault lines. 

North and northwest of Mubi the Basement plains are underlain by extensive areas of ironpan. 

In many places the ironpan is exposed in the break of slope to the streamlines and the 

interfluve is bounded by a distinct scarp. Apart from the relatively gentle relief of the 

plains where ironpan is developed, the Basement plains are generally more dissected with 

straight gentle slopes descending from narrow interfluves to streamlines with only narrow' 

and impersistent floodplains. In many areas the interfluves are capped by ironpan and ironpan 

also forms rocky scarps in the valley-side slopes. 

The Older Granites and other predominantly granitic rocks of type 2 are more commonly 

associated with hilly and highland areas. They form groups of inselbergs, massive steepsided 

hills and mountain ranges. The Older Granites generally have a widely spaced, strongly 

developed pattern of rectangular jointing which controls the well developed rectangular 

drainage pattern. The highest summits in the generally rugged Mandara Mountains rise to over 

1 200 m (4 000 ft) from the pediment slopes, which in turn rise steadily southwards from 

450 m at Gwoza to 600 m south of Mubi (1 500-2 000 ft). Within the mountain range, between 

the pediment and the summits, there are areas of more gentle relief. These intermediate 

levels have not been fully investigated, but aerial photographs show that their general 

appearance is remarkably consistent throughout the range and contour maps (DOS series 430) 

60

show that they occur at two levels: about 760 m (2 500 ft) and 900 m (3 000 ft). These 

levels are not controlled by lithological changes and they are therefore presumed to 

represent relics of successive planation surfaces, higher than the surface represented by the 

Uba Plains. Similar higher surfaces occur in the Zummo Mountains south of the Mandara range. 

Summit levels in the Gaanda Hills are not as high as those in the Mandara Mountains. The 

Hills consist of groups of inselbergs between which are relics of more gentle terrain at the 

same altitude as parts of the Uba Plains, but higher planation surfaces have been recognised. 

The Hills contain large areas of bare rock and shallow stony soils and in general the 

regolith is thin and discontinuous. These Hills, extending from east of the Zummo Mountains 

near the Nigerian frontier to the escarpment bordering the Hawal river on the east of the 

Gongola Valley,represent a wide-stripped zone separating the planation surface of the Uba 

Plains from the more recent erosion cycles in the Gongola and Benue Valleys. 

The granites and other igneous rocks grouped under rock type 3 also give rise to hills. The 

Younger Granites in the extreme northwest form isolated inselbergs which rise from beneath 

the surrounding sand plain. The granites, porphyries and lavas in the Gongola Valley form 

steep hills associated with the adjacent hill masses formed on Older Granites. 

Landforms Developed on Rocks of Group II: Cretaceous Sediments 

The form of the plains underlain by Cretaceous sediments is closely related to the different 

resistance to erosion of the various rock types and the topography closely reflects the 

varying lithology and the geological structure. In general the clays, shales and limestones 

of the transitional and marine facies (rock types 5 and 6) are less resistant and therefore 

form lower-lying flatter areas. Many of the small hills, ridges and depressions within these 

areas are directly controlled by detailed variations in lithology. Plains are formed on 

sandstones of the continental and transitional facies (rock types 4 and 5) where they are 

only gently folded, but these plains generally show a greater range of relief and are more 

undulating than the clay plains. 

The more strongly folded continental sandstones generally form steep-sided hill ranges, 

ridges or isolated more rounded hills. In the Benue Valley and the southern half of the 

Gongola Valley the hill ranges are composed largely of folded Bima Sandstone and sandstones 

of the Yolde Formation. The general east-west alignment of these ranges closely follows the 

structural trends of the main fold belts. Several of the hill ranges are asymmetrical with 

the steeper slopes coinciding with the steeper limbs of the folds. Further north in the 

Gongola Valley there are fewer hills and they stand less high above the adjacent plains. 

They are again closely related to the sandstone members of the folded Cretaceous strata. The 

smaller number and reduced size of the hills generally reflects the less intense folding 

which has affected the area. The form of the Gulani hills closely follows the north-south 

fold axes in the Gulani Sandstone. Further north the Bima Sandstone forms both hills and 

undulating plains and again the distinction seems to depend on the intensity of the folding. 

Folded Gombe Sandstone forms hills along the western border of the Gongola Valley adjacent to 

the Kerri Kerri Plateau. In some areas on the southern margin of the Plateau, hills are 

related to structural trends in the Gombe Sandstone which can be clearly distinguished on the 

aerial photographs beneath a thin cover of Kerri Kerri Sandstone. 

Landforms Developed on Rocks of Group III: Kerri Kerri Sandstone 

Kerri Kerri Sandstone underlies both the Kerri Kerri Plateau and the Potiskum Plain to the 

north of it. The Plateau consists of undulating to gently rolling plains 300 -600m (1 000 to 

2 000 ft) above sea level. The drainage pattern is widely spaced with streamlines as much as 

1.6km (1 mi) apart. In the north tributary streams flow in narrow V-shaped valleys to the 

floodplain of the Gongola. Further south the Pai and its major tributaries have flat-floored 

valleys bounded in most places by steep sides rising to the more gentle Plateau slopes. 

Throughout the Plateau the gentle upper slopes are straight or smoothly convex with only 

occasional small low hills and mesas standing above the otherwise uniform interfluve level. 

In the northern half of the plateau a linear pattern of north-south orientated low undulations 

can be distinguished on aerial photographs. These undulations have not been investigated in 

detail on the ground, but they are most likely to be relic dunes. 

61

In some areas the Plateau is bounded by a high escarpment dissected into a series of steep 

flat-topped ridges and flat-floored valleys. This escarpment form is due to the easy erodibility 

of the sandstone. Elsewhere the Plateau is bounded by a more gradual descent, marked 

by a break of slope but without a distinct escarpment. This more gentle descent is complicated 

in the east by sandstone hills on the edge of the plateau. 

The Potiskum Plain is flat to very gently undulating and descends gradually northeastwards 

from 395-330 m (1 300- 1 100 ft). Drainage lines are widely spaced in broad, partially 

drift-filled shallow valleys. The Plain is formed over virtually flat-lying Kerri Kerri 

Sandstone on which ironpan has been extensively developed. Southeast of Potiskum, near Kadi, 

it stands above the Kerri Kerri Plateau and is separated from it by a strongly dissected 

escarpment. Some parts of the escarpment face show as much as 10 m (33 ft) of ironpan over 

the unaltered sandstone. Ironpan cappings form small mesas east of Potiskum. Over the 

remainder of the Plain, ironpan and ferruginised sandstone form only scattered low scarps and 

there are only occasional hills. Similar mesas capped by ironpan occur between Damboa and 

Buni in the Korode Escarpment. 

Landforms Developed on Rocks of Group IV: Volcanic Rocks 

Volcanic rocks occur as isolated plugs and extensive lava flows (rock type 9) and as pyroclastic 

rocks (rock type 10). Basalt plugs and cones occur mainly in the southern half of 

the Gongola Valley and in the Benue Valley. They are more resistant than the Cretaceous 

sediments into which they are intruded and therefore tend to form hill features. These vary 

from small dome-shaped hills a few meters high to towering conical hills rising more than 

300 m (1 000 ft) above their surroundings. They are most numerous between Filyia and 

Kaltungo where they dominate the hills formed on Bima Sandstone. 

The Biu Plateau and Biu Plains are formed over the most extensive series of lava flows. The 

Plateau consists of undulating plains between 600 -300 m (2 000 - 2 600 ft) above sea level 

formed over a series of overlapping horizontal lava flows. Within the Plains there are many 

low scarps and occasional larger escarpments which mark the end of individual flows. Boulder 

screes and mud flows are also associated with some flows. In the west, south and southeast 

the Plateau is bounded by a strongly dissected major escarpment rising through 150 - 300 m 

(500 -1 000 ft). The boundary in the northeast is less pronounced, and in many places is 

marked only by a low scarp 3-6 ra (10 - 20 ft) high. The Biu Plains, which extend northeastwards 

from this low scarp, consist of gently sloping basalt plains with a range of relief 

which seldom exceeds 3-6 m (10-20 ft). Rock outcrops are rare except where low scarps and 

boulders are associated with the limit of individual lava flows. Some minor variations in 

relief are associated with mud flows in between lava flows. The drainage lines are widely 

spaced and lie in broad shallow depressions. 

The Longuda Plateau is also formed on a sequence of horizontal lava flows. The upland plains 

which make up the Plateau are far less extensive than on the 3iu Plateau and they are more 

dissected. Scarps and boulder screes are common and the Plateau is bounded by an escarpment 

on all sides. Less extensive lava flows occur at Garkida and Song. At Garkida lavas form a 

flat to gently sloping plain surrounding steep-sided volcanic cones, several of which contain 

well preserved central craters. The lavas blocked the Hawal river and are responsible for 

the abrupt change of form at this point. At Song the lavas flowed from similar steep-sided 

cones with well preserved craters. They followed existing valleys which were partially 

infilled by basalt, but have been subsequently exhumed, so that now basalt flows border many 

•of the streamlines and the underlying Basement rocks form the interfluves. The hills on the 

Biu Plateau between Meringa and Buratai are formed of pyroclastic rocks with locally developed 

lava flows. They are steep-sided volcanic cones and vents with summits as much as 180 m 

(600 ft) above the Plateau. Many show well developed craters and breached rims. One of the 

best known is Tilla where the crater contains a spectacular perennial lake. 

Landforms Developed on Rocks of Group V: Chad Formation 

Consolidated sediments of the Chad Formation (rock type 11) are exposed, or lie near the surface, 

south and west of Damaturu and southwest of Maiduguri. Elsewhere they are covered by 

unconsolidated superficial deposits (rock types 12-17) and it is with these more recent 

deposits that the landforms are closely associated. 

South and west of Damaturu the northern boundary of the Gongola Valley is marked by a series 

of dissected plains rising to a marked break of slope with the Damaturu Plain. In some 

places this break forms a low escarpment. Below the escarpment the plains are undulating. 

62

with finely eroded gentle slopes cut mainly in Chad sandstones descending to flat-bottomed 

valleys most of which are underlain by Cretaceous Pika Shales. Mesas formed from sandstones 

capped by ironpan stand above the plains. This dissected zone is the northward continuation 

of the stripped zone formed by the Gaanda Hills and the escarpment to the Biu Plateau. It 

marks the limit of erosion cycles now active in the Gongola Valley. Southwest of Damaturu 

the Anumma river changes abruptly from flowing northwest to flowing southwest. It seems 

probable that a previous tributary of the Damaturu river has been captured by headward 

erosion of the Anumma and that this change in direction marks the elbow of capture. The 

elbow of capture is associated with a nick point in the river profile and the upstream part 

of this valley probably owes its form more to erosion on the southern edge of the Chad Basin 

prior to the capture than to erosion governed by the Gongola base level. 

Southwest of Maiduguri the southern part of the Damaturu Plain consists of very gently 

undulating plains with broad low interfluves and wide flat depressions. This topography is 

cut in Chad sediments partially overlain by drift, and many of the depressions are floored by 

Chad clays. Near Damaturu some of the interfluves are low mesas formed of sandstone capped 

by ironstone which is in turn overlain by drift (Klinkenberg, personal communication). 

The plains which lie to the north of these gently undulating plains are relatively featureless 

and consist of hummocky plains with only minor undulations. The maximum height difference 

between crest and hollow does not exceed 1. 5 m (5 ft). There are no dunes although 

some of the depressions have a northeasterly linear orientation parallel to that of the 

dunes in the Lantewa Dunefield to the north. In some areas the hummocks have a similar 

orientation. Some parts of the Damaturu Plain show a ripple pattern of very gentle undulations 

with low crests 200-300 m (660- 1 000 ft) apart. In general these undulations run 

north and south, but the pattern is distorted in the largely drift-filled valleys where the 

ridges tend to run down the valley slopes across the contours. The pattern of these undulations 

is emphasised by lines of woody vegetation concentrated in the depressions and it is 

easier to recognise this linear vegetation pattern on aerial photographs than to recognise 

the undulations on the ground where the maximum range in relief is of the order of lm(3 ft). 

Grove (1958) attributes these undulations to relic dunes. A similar interpretation has been 

given to comparable patterns in Sokoto by Clayton (1966) and PAO (1969). They relate the 

vegetation differences to a contrast in the soil moisture status between the ripple and the 

interripple areas. 

Dunes are the most prominent and widespread landforms associated with the aeolian sands of 

rock type 12. In the central and western parts of the area the dunes are of the sief type 

and form a regular pattern of long parallel sand ridges. These longitudinal dunes predominate 

in the Lantewa Dunefield and extend northwards into the Yobe River Complex. They are 

constantly orientated east-north-east. Over most of the Dunefield the dunes form a regular 

pattern of parallel ridges between 0.75 km Ok. mi) and 1.25 km (% mi) apart. Some are as much 

as 16 - 24 km (10 - 15 mi) long although they are more commonly broken by small discontinuities. 

The dune crests are generally between 3 and 9 m (10-30 ft) above the interdune depressions. 

The dunes are best developed in the north of the Dunefield where in some places they are as 

high as 11 m (36 ft). Along the southern border they are less frequent, shorter and generally 

not more than 3m (10 ft) high. In the Yobe River Complex the interdune areas are part of 

the alluvial plain; the dunes rise abruptly 6-9 m (20-30 ft) above the plain. Further north 

less well developed dunes of the same sief type and orientation occur in the Manga Plains- 

There are similar northeast-orientated longitudinal dunes east of Bama. The interdune areas 

are covered by later lagoonal and deltaic deposits. Similarly orientated but less well 

developed dunes occur on the southeastern edge of the sand plains between Maiduguri and 

Mongonu. These dunes are also separated by later alluvial deposits. Northeast of these 

longitudinal dunes aeolian sands form islands which stand as much as 7 m (23 ft) above the 

surrounding flat clay plains. Pullan (1964; 1969) has shown that the lagoonal clays (rock 

type 15) were deposited over an undulating sand surface; in the south the highest remnants of 

this partially buried surface are the longitudinal dunes; further north the orientation of 

the dunes is lost and the sand plain emerges as the scattered sand islands. Together these 

dunes and islands represent the most easterly extension of the Lantewa Dunefield. 

Aeolian and fluviatile sands of rock type 12 also predominate north of the Maiduguri to 

Mongonu road and dunes are again the dominant landform in an otherwise featureless sand plain. 

The area has been described by Pullan (1964). The most extensive group of dunes is orientated 

north-north-west to south-south-east, that is transverse to the orientation of the 

longitudinal dunes. They form ridges up to 2.4 km (1& mi) long and roughly 3. 2 km (2 mi) 

63

apart. They have an asymmetrical cross section and are steeper on the east-facing slope. 

The dunes are highest north and east of Gudumbali where they reach a maximum elevation of 

15 m (50 ft). Further west they are much lower but the alignment can still be seen. In the 

northeast the dunes are separated by clay flats; elsewhere the interdune areas consist 

mainly of hummocky windblown sands. 

The Lantewa Dunefield and the Damaturu Plain are separated from the Gudumbali Dunefield and 

the Bama Deltaic Complex by a complex ridge of beach sands (rock type 13), which can be 

traced from the Niger frontier east of Geidam, southeast through Maiduguri and Bama, to the 

Cameroon frontier. The continuation of this sand ridge into the Niger Republic has been 

mapped by Bocquier and Gavaud (1964) and into Cameroon by Pias and Guichard (1957). Its full 

extent has been summarised by Gavaud (1969). In Nigeria the ridge - known as the Bama Ridge - 

attains its maximum development between Maiduguri and Bama where it stands 12 m (40 ft) above 

the surrounding plains. It has been interpreted (Grove and Pullan, 1963) as an ancient 

barrier beach, or in some sections as a near-parallel series of such beaches or offshore bars 

formed when Lake Chad stood 53 m (174 ft) above its present level. The full extent of this 

larger lake has been summarised by Grove and Warren (1968). The largely dune-free sand plain 

which lies immediately to the east of the Bama Ridge and descends gradually from it is the 

beach of the former lake. 

Grove and Pullan (1963) and Pullan (1964) recognise a similar but smaller beach ridge running 

west from Gambaru on the Cameroon frontier towards Mongonu. North of Mongonu the belt of 

lacustrine sands bordering Lake Chad (rock type 16) forms a series of parallel beach ridges 

which continue as far north as Arege. This second, more recent, series of beach ridges has 

been mapped in Niger by Bocquier and Gavaud (1964). 

The deltaic deposits of rock type 14 which underlie the Bama Deltaic Complex form extensive 

sand and clay plains with little variation in relief. The pattern of landforms within these 

plains is very complex and is better appreciated from aerial photographs than on the ground. 

It consists of levees, meander channels and spill plains associated with several previous 

courses of the rivers together with similar landforms which are developing at the present 

time. Recent fans are developed at Maiduguri and Bama where streams break through the Bama 

Ridge. The central part of the Complex, between Maiduguriand Bama, consist largely of older 

deltaic landforms which have been considerably degraded by wind action and are partially 

masked by windblown sand. Near the Maiduguri to Mongonu road the transverse and longitudinal 

dunes of the Gudumbali Dunefield pass gradually into the deltaic sand and clay plains. The 

area consists of large interlocked clay plains with scattered sand islands. Many of the clay 

plains and the sand islands have the same northeast alignment as the longitudinal dunes. The 

complex pattern of deltaic landforms is further complicated by locally developed barchan dunes 

and by the longitudinal dunes and sand islands which emerge from beneath the cover of deltaic 

deposits and have become partially combined with them by subsequent wind action (Pullan, 19R4). 

The lagoonal clays of rock type 15 are known locally as 'firki'. They form extensive flat 

clay plains above which the sand islands stand as high as 7 m (23 ft). In detail the plains 

consist of clays deposited in a series of shallow basins which have coalesced and have connecting 

or centripetal drainage. The basins are flooded annually, both by rain water and by 

water from the major rivers, and in some places clay is being deposited at the present time 

by these flood waters. 

The sand plains and dunefields have been traversed in the past by several river systems, 

some of which do not now carry water, or carry far less water than they did in the past. The 

valleys containing these rivers have subsequently been partially filled by windblown sand and 

they are now to a large extent fossil. 

The most extensive of these fossil river systems flows south from Niger, across the Manga 

Plains to join the Yobe River Complex near Gashua. Further east the complex pattern of 

largely drift-filled river courses and poorly developed dunes is further complicated by a 

series of steep-sided closed depressions; some are connected by the fossil drainage system, 

others are isolated. They are as much as 15 m (50 ft) deep; the larger ones lie below the 

level of the fossil river system and contain standing water. They occur over a wider area 

in Niger; only a small portion of their total extent lies within Nigeria. The Lantewa 

Dunefield and the Damaturu Plains are crossed by several river courses which have previously 

had wider valleys and a greater extent; the valleys are now partially drift-filled and 

largely fossil. 

64

Ancient alluvial deposits of rock type 17 are most extensive in the Yobe River Complex and 

south of Bama in the Bama Deltaic Complex. The landforms associated with these deposits 

include ancient levees and point bars, spill plains, backswamps and meanders. Many of these 

landforms have subsequently been degraded by wind action and are now partially masked by 

windblown sand. Several stages of river deposition are contained in the Yobe River Complex, 

ranging from the present floodplain (see Group VI below) to the oldest alluvial deposits 

which covered the interdune areas of the longitudinal dunefield and are probably associated 

with the Hadejia river when it flowed into the more extensive Lake Chad near Gashua (Grove 

and Pullan, 1963). Some of these older deposits probably have a deltaic origin, but no distinction 

between deltaic and riverine landforms has been made. South of Bama ancient alluvial 

deposits form extensive terraces which border the present floodplain. Similar landforms 

border parts of the present floodplain of the El Beid river on the Cameroon frontier. 

Ancient alluvium and its associated landforms are far less widespread in the Benue and 

Gongola river systems. Old meanders, levees and point bars mark previous courses of the 

Tiel river on the Cameroon frontier and bound the present floodplain of the Loko further 

west. Near Snellen terraces, old spill plains and levees border the present floodplains of 

tributaries to the Gongola; clay plains formed over ancient backswamps of the Benue occur 

near Karim Lamido. 

Landforms Developed on Rock Types of Group VI: Recent Alluvium 

Recent river alluvium occurs along most of the water courses in northeast Nigeria. It varies 

in extent from thin discontinuous sands in the smallest streams to thick broad sands and 

clays on the major rivers. The sands form levees and point bars. Levees predominate in the 

smaller, generally fast-flowing streams; the broader, slowly flowing rivers have a complex 

pattern of both levees and point bars. Within this pattern clays are associated with backswamps 

and abandoned meanders. 

Pediments and Colluvial Fans 

Pediments are formed over both the Basement Complex and Cretaceous sandstones in northeast 

Nigeria and it is convenient to describe them separately in association with the colluvial 

deposits which mantle them. 

The two most extensive pediments are those bordering the Mandara Mountains and the Gaanda 

Hills, the latter pediment continuing north, west of the escarpment to the Biu Plateau. The 

western border of the Mandara Mountains is marked by a pediment which descends gradually 

westward to the Uba Plains from the sharp break of slope with the mountain mass. In the 

north the pediment continues round the main mass of the mountains east of Gwoza into the 

Cameroon Republic. The Pediment on this eastern side of the mountains is covered by up to 

10 m (33 ft) of gravels and the underlying solid rock is not exposed (Pullan, 1969). The 

gravels have been deposited by streams from the mountains and by distributaries of the 

Ngoshi river, which has occupied various courses during its development. These gravel 

deposits have been strongly eroded and are now cut by many deep gullies. North and west of 

the Mandaras the pediment descends gradually towards the Bama Deltaic Complex. On its upper 

slopes it is overlain by gravel fans formed from outwash fans of both past and present 

streams draining the mountains; further downslope the gravels give way to finer deposits and 

clays characterise the lower slopes. The gravels of the upper slopes are eroded by many 

gullies; in some places the mid-slopes show gravel over the finer deposits which suggests 

that the upper pediment deposits have been eroded and redeposited (Pullan, 1969). South of 

Magadali the pediments between the Manadara Mountains and the Uba Plains are generally narrow 

and occur in deep valleys within the main mountain mass. Many of the pediment slopes have 

been covered by gravel fans which now form deep pedisediments and are in places strongly 

eroded into a fine network of gullies. 

The southern edge of the Gaanda Hills is marked by a sharp concave break of slope with the 

pediment which descends gradually to gently undulating plains. The break of slope coincides 

with the boundary between Basement Complex rocks of Group I and Cretaceous rocks of Group II. 

This pediment is primarily an area of sediment removal and is largely free from colluvial 

deposits. It is floored by a thin cover of Bima Sandstone over the Basement, and as erosion 

continues the original surface on which the Sandstone was deposited is being exhumed. 

Further north in the Gongola and Hawal valleys the same pediment bevels Basement rocks as far 

as Garkida; it continues north of the Hawal, but occupies only a small area within the lower 

slopes of the Biu escarpment. Again most of this area is one of sediment removal and colluvial 

deposits are rare. 

65

Pediments are formed on Basement Complex rocks around most of the inselbergs. Where the 

inselbergs are scattered the pediment forms only a small peripheral apron with only locally 

developed fans. At Hong and other places where the inselbergs occur in groups, the individual 

pediments coalesce to form extensive plains sloping away from the inselbergs and the 

streams draining them form extensive fan deposits. The other main pediment in the project 

area is developed over Bima Sandstone on either side of the Lamurde hills bordering the 

Benue Valley. Colluvial deposits derived from the hills are widespread over the pediment and 

gravel fans are common. 

Colluvial fans are a common feature of the eastern border of the Kerri Kerri Plateau, where 

the easily eroded Kerri Kerri Sandstone has been washed down and over the lower slopes formed 

on older Cretaceous rocks. The fans are not, however, deposited over a rock pediment 

formed on these rocks.. 

Geomorphological History 

Falconer (1911) attempted to elucidate the major crustal movements and drainage changes 

which have affected Nigeria. Many of his ideas have been followed by later workers, although 

this seems not always to have been acknowledged. Pugh and King (1952) outlined the 

geomorphological history of Nigeria, as a whole, but in the last 20 years most geomorphological 

investigations have tended to concentrate on certain problem areas: the high surfaces 

of the Mandara Mountains and the Jos Plateau, the plains adjacent to the Plateau, the 

evolution of the Benue Valley, or on the Pleistocene evolution of the Chad Basin. This land 

resources investigation of North East Nigeria has required a certain amount of geomorphological 

correlation between these different areas. It has considered some areas not previously 

investigated, but in many respects this has served only to demonstrate that, with the present 

state of knowledge, only a very generalised geomorphological history of the North East 

project area can be attempted here. 

Most workers regard the present landscape of Northern Nigeria as an arrangement of planation 

surfaces at different levels separated by escarpments or broad dissected zones. There is 

considerable range of opinion however about the nature, origin and evolution of these surfaces. 

The main sequence of events since the Jurassic was suggested by Pugh and King (1952). 

Their framework has been generally adopted, even if there is not general agreement that 

pediplanation is the process involved in the formation of the planation surfaces which they 

identified. Pugh and King (1952) consider that the whole of Nigeria was reduced to a vast 

pediplain at the end of the Jurassic, and that this plain formed part of the continent of 

Gondwanaland. Pugh (1954) interpreted the remnant higher erosion levels in the Mandara 

Mountains as relics of this Gondwana surface. Later Pugh (1955) and King (1962) suggested 

that, although the highest level could be remnants of the Gondwana surface, the more extensive 

intermediate levels in this area were remnants of a later erosion cycle. 

It is generally accepted that the continent of Gondwanaland began to break from the south and 

affected West Africa in the late Jurassic and early Cretaceous (Smith and Hallam, 1970). 

During the break-up the areas now represented by the Niger and Benue Valleys in Nigeria were 

the focus of major fracture lines separating South America from Africa. The Benue/Gongola 

trough was formed at this time as a northeast-trending tensional graben (Wright, 1968). 

North of the Benue the stable Basement areas which bordered this trough now form the Bauchi 

Plains (extending beneath the Kerri Kerri Plateau) and the Gaanda Hills (extending beneath 

the Biu basalts). The floor of the trough subsided intermittently during the Upper 

Cretaceous and well over 3 000 m (10 000 ft) of sediments were deposited in it. It seems 

probable that the stable masses on either side of the graben were subjected to intermittent 

region uplift to compensate for this subsidence. The sediments buried the main rift faults 

and overlapped onto the downwarped margins of the trough (Cratchley and Jones, 1965). The 

sedimentary material was derived from erosion of the uplifted Gondwana Basement surface, with 

the consequent creation of a second extensive planation surface on the Basement rocks. This 

surface probably continued across the Cretaceous sediments in the Benue/Gongola trough as a 

depositional surface. 

At the end of the Cretaceous the sediments in the Benue/Gongola trough were subjected to compressional 

folding, as a result of the release of the tensional stresses which formed the 

graben structure (Wright, 1968). These earth movements were probably accompanied by uplift 

along an axis extending from Katsina, through Jos southeast towards Mambilla (Grove, 1957). 

The net effect of this deformation and uplift of the post-Gondwana surface was to create a 

66

major upland watershed area along this axis and downwarped areas to the northeast. By the 

Miocene the post-Gondwana surface had been considerably eroded, the resulting African surface 

was developed on both Basement and Cretaceous rocks and the continental Kerri Kerri Sandstone 

had been deposited in basins within the downwarped area. Pew fossils have been found in the 

Kerri Kerri Sandstone and its age is uncertain. Carter et al. (1963) and Reyment (1965) 

suggest Palaeocene, although they allow that it may be younger. Haughton (1963) tentatively 

assigns it to the Eocene. Sandstone accumulation had therefore probably ceased in these 

basins by the latter part of the Eocene and rivers started to flow northeast across the 

newly formed depositional and denudational African surface. It seems most likely that the 

Jamaare, Komadugu Gana and Yedseram, and the present-day upper reaches of the Gongola and the 

Hawal were initiated at this time. Over the same period in the southwest the lower reaches 

of the Benue (the proto-Benue) had cut headwards in the less resistant Cretaceous sediments 

providing a much lower base level for planation (Grove, 1957). 

King (1962) suggests that further uplift occurred in the Pliocene and initiated another cycle 

of erosion. This post-African cycle is represented by the Uba Plains and by the Bauchi 

Plains to the west of the project area. Further north this post-African planation surface is 

downwarped below the Chad Formation. 

During the Pliocene extensive sheets of ironpan (laterite) developed over the post-African 

planation surface (du Preez, 1956). These are preserved on the Basement plains north and 

west of Mubi, under a thin cover of drift on Kerri Kerri Sandstone of the Potiskum Plain and 

in the Kadi Escarpment (Dowling, 1963) and on the Gombe Sandstone at Fika; elsewhere in the 

more dissected areas only remnants of primary ironpan are preserved. Pullan (1968) has described 

the types of primary ironpan which occur and the range of secondary ironpan deposits 

which have been subsequently derived from them. More than one phase of ironpan formation has 

been recognised, but the age relations are not fully understood. South of Damaturu, 

Klinkenberg (personal communication) has mapped ironpan overlain by Chad sediments; further 

west, Hope (personal communication) has mapped mesas of Chad sandstones preserved by a capping 

of ironpan. 

Probable movement of the West African monocline (King, 1962) at the end of the Pliocene 

involved more uplift and warping. Further cycles of erosion, related to changes in oceanic 

base level, progressed up the Benue trough and resulted in a considerable enlargement of its 

catchment (Grove, 1956). During this enlargement tributaries extended northwards to capture 

the Gongola and the Hawal. The boundary between the planation surfaces related to the post- 

African erosion cycle with an inland base level, and surfaces related to later cycles controlled 

by the present oceanic base level of the Gongola and Benue,is marked by a stripped 

zone which extends from the southern edge of the Mandara Mountains, through the Gaanda Hills 

and the western escarpment of the Biu Plateau and west to the Kadi Escarpment and the western 

edge of the Kerri Kerri Plateau. This stripped zone continues further west, beyond the North 

East project area, between the Kerri Kerri Plateau and the Bauchi Plains. 

In the Benue Valley, west and south of the North East project area, Grove (1956) has recognised 

a planation surface between 450 -580 m (1 500 - 1 900 ft) related to oceanic base level. 

It seems likely that the plains in the Gongola Valley around Kaltungo and to the west of the 

Biu Plateau were formed by the same erosion cycle. Grove has shown that the subsequent cycle 

had several phases and has recognised lower surfaces at 180 and 100 m (600 and 330 ft). Both of 

these lie west of the North East project area and, although erosion has continued in the 

Gongola Valley throughout this cycle to the present day, no surfaces related to these two 

phases have been recognised. 

The region now occupied by the Chad Basin has been a depositional region almost continuously 

since the continental sandstones of the Kerri Kerri Formation were deposited in downwarped 

basin areas of the post-Gondwana surface. After deposition of these sandstones and the 

establishment of the northeast-orientated drainage across the post-African planation surface, 

downwarping continued and the sediments of the Chad Formation were deposited. The total 

amount of downwarping is indicated by the depth to pre-Chad rocks; at Goniri (south of 

Damaturu) the base of the Chad Formation is 89 m (290 ft) below ground level, at Maiduguri 

580 m (1 900 ft) and on the shore of Lake Chad north of Mongonu 760 m (2 500 ft). 

There has been considerable climatic fluctuation since the Pleistocene. These climatic 

fluctuations are reflected in the sequence of superficial deposits overlying the rocks of the 

Chad Formation, and the landforms associated with them. Pullan (1964) has suggested a tentative 

chronology for these fluctuations in Nigeria, and the following paragraphs are largely a 

summary of his observations. 

67

The characteristics of the sands forming the extensive plains west of the Bama Ridge suggest 

that they were of fluvial origin - derived mainly from Basement rocks to the south and west. 

Their aeolian character and the longitudinal dunefields were formed subsequently during an 

arid phase when desert conditions extended as far south as 11° 30' N. The Bama Ridge truncates 

these longitudinal dunes and is younger than them. The shoreline of Lake Chad at this 

stage was 333 m (1 095 ft) above sea level and extended west from Magumeri as far as Gashua 

(Grove and Pullan, 1963). The extensive clay flats which now lie within the Yobe River 

Complex in the vicinity of Geidam were probably deposited in lagoons behind the beach ridge. 

At this period the Yobe river system included many south-flowing tributaries from the Niger 

Republic and northeast-flowing tributaries from the Potiskum and Damaturu Plains. These are 

now largely fossil and do not reach the main river system. The change in direction of the 

Yobe river at Damasak, from an easterly to a northeasterly direction, and the presence of a 

large quantity of sand to the south suggests that the Yobe built a large delta of coarse sand 

into Lake Chad east of the beach ridge. The large lake with which the beach ridge and this 

delta were associated flooded parts of the longitudinal dunefield. Deltas were also formed 

by the Yedseram and the Alo rivers until they reached the beach ridge. The way in which both 

these rivers have been deflected from their course by the beach ridge suggests that it 

existed before the river deltas reached it and that the rivers finally broke through gaps in 

the ridge. 

Por the delta sands deposited in the area now occupied by the Gudumbali Dunefield to have been 

formed into dunes, a regression of the lake from the line of the Bama Ridge must have followed. 

Pullan suggests that the dunes in this dunefield were formed along an open shoreline as the 

lake gradually retreated to its present position. Further south the dunes were confined by 

clay flats formed by the extended deltas of the Yedseram and the Alo. The extent of the 

regression of the lake at this period is not known but it was probably of short duration. A 

further transgression, rather than a period of stillstand, is suggested by the clays and 

silty clays in the interdune areas in the eastern half of the Gudumbali Dunefield. During 

this transgression the lake also flooded part of the longitudinal dunes east of Bama. 

This postulated increase in the lake size is associated with a further series of river deltas. 

The course of the Yobe was blocked by the transverse dunes and formed a delta further north, 

largely to the north of its present course. The large fossil delta to the north of the 

present Yedseram delta was probably built during this transgression. There is also some 

evidence that the Alo may have been a tributary of the Yedseram at this stage, because southwest 

of the Bama Ridge they are separated by only a few miles of low-lying ground and there 

is no old delta of the Alo comparable in size to that of the Yedseram. Further east the El 

Beid was part of the Chari river delta. This delta extended far into the lake and from it the 

Ngelewa sand ridge formed as a spit or an offshore bar. The lagoonal deposits of the Yedseram 

and the El Beid deltas, which now form the 'firki' clay flats, were confined northwards by 

this Ngelewa ridge. 

A gradual reduction in the area of the lake followed this last transgression and was accompanied 

by the building of small deltas by the Alo and Yedseram. These rivers are now extending 

their deltas into seasonal shallow lakes impounded by the Ngelewa ridge and the lacustrine 

sands bordering the present lake. Records of the lake level and river discharges are 

not adequate to tell whether the lake is retreating further from its present shoreline. 

68

PLATE 1/5 The road to Dikwa across the 'firki' (black 

cracking clay plains). A 'sand island' lies along 

the skyline. 

PLATE 1/6 The Bama Ridge just west of Maiduguri. Looking 

eastward along the southern face with the deflected 

Ngadda river flowing towards the camera. 

69

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SURFACE WATER 

HYDROLOGY 

by 

M G Bawden 

The North East project area includes parts of two major drainage basins: the internal basin 

of Lake Chad and the Benue river basin which flows to the Niger and then to the Atlantic 

Ocean. Text Map 11 shows the main catchment areas in the project area. The area of each of 

these catchments within the detailed boundary of the project is shown in Table 2. Table 3 

shows the mean monthly and mean annual discharge for each of the rivers for which sufficient 

data are available. 

TABLE 2 Area of river system catchments inside project boundary 

River system 

Lake Chad Basin total area 

*Yobe river system 

Damaturu river system 

Kyauwo river system 

Yedseram river system 

*E1 Beid river system 

areas with only local surface flows 

Area 

km 2 mi 2 

(2 335 000) 

21 200 

4 200 

3 500 

14 600 

4 400 

58 400 

(900 000) 

8 200 

1 600 

1 300 

5 700 

1 700 

22 500 

Total 106 300 41 000 

Benue River Basin total area 

»Gongola river and undifferentiated 

tributaries 

Hawal river system 

Anumma river system 

•Benue river and undifferentiated 

tributaries 

*Tiel river system 

Kilunga river system 

*Pai river system 

(337 000) 

24 300 

11 900 

5 100 

7 700 

1 300 

5 700 

13 700 

(130 000) 

9 400 

4 600 

2 000 

3 000 

500 

2 200 

5 300 

Total 69 700 27 000 

* River systems which extend beyond the detailed boundary of the North East Project

TABLE 3 Mean monthly and mean annual discharge of selected rivers 

Mean monthly discharge in m 3 /s for eight stations Mean monthly stage cm 

River Benue Gongola Yobe Ngadda Yedseram El Beid 

Station Yola Numan Lau Bare Damasak Gashagar Yau Maiduguri Bama Gambaru 

Period of 

record 1955-1957 1955-1957 1959-1964 

1955-1958 

1963-1965 

1955-1960 1957-1962 

January 100 NA 190 NA 28 25 23 0 0 323 

February 30 NA 110 NA 6 7 11 0 0 169 

March 23 NA 67 NA < 1 2 2 0 0 59 

April 16 NA 45 > 1 0 0.4 5 0 0 16 

May 45 56 121 52 0 0 > 1 0 0 4 

June 327 395 415 127 > 1 0 0 0 0 4 

July 879 953 1 188 239 9 6 4 1 0.92 20 

August 2 150 2 400 2 915 683 30 22 17 22 64 153 

September 3 583 4 500 4 678 972 42 34 23 47 140 145 

October 3 033 3 200 3 615 565 47 35 25 36 76 164 

November 597 637 685 NA 55 37 27 14 22 280 

December 220 150 402 NA 58 40 29 4 0 395 

Mean annual 

discharge 730 NA 1 081 NA 25 17 14 10 12 m 3 /s 72 m 3 /s 

TABLE 3A Mean monthly and mean annual discharge of selected rivers 

Mean monthly discharge in ft 3 /s(cusecs) for eight stations Mean monthly stage ft 

River Benue Gongola Yobe Ngadda Yedseram El Beid 

Station Yola Numan Lau Bare Damasak ( jrashagar Yau Maiduguri Bama Gambaru 

Period of 

record 

1955-1957 1955-1957 1959-1964 

1955-1958 

1963-1965 

1955-1960 1957-1962 

January 3 530 NA 6 707 NA 985 884 820 0 0 10.61 

February 1 059 NA 3 883 NA 222 239 382 0 0 5.54 

March 812 NA 2 365 NA 42 53 72 0 0 1.95 

April 565 NA 1 589 10 0 14 166 0 0 0.52 

May 159 1 977 4 271 1 818 0 0 3 0 0 0.12 

June 11 543 13 944 14 650 4 483 0.8 0 0 0 0 0.13 

July 31 029 33 641 41 936 8 437 328 206 124 45 0.03 0.67 

August 75 895 84 720 102 900 2 411 1 070 789 612 766 2.10 5.03 

September 126 480 158 850 165 133 34 312 1 493 1 184 808 1 646 4.58 4.75 

October 107 065 112 960 127 610 19 945 1 660 1 223 893 1 274 2.50 5.39 

November 21 074 22 486 24 181 NA 1 938 1 313 960 485 0.72 9.18 

December 7 766 5 295 14 191 NA 2 057 1 398 1 032 152 0 12.95 

Mean annual 

discharge 25 800 NA 38 200 NA 815 601 497 363 

72 

417 

cusecs 

2544 

cusecs

GROUNDWATER AREAS TEXT MAP 10 

10° 12° 14° 

14° 1 l \ 1 V '"* 

'>r 

SCALE 1:3 ,000,000 

\ + \ 

^ — + C\/^ 

\ + ) 

*7A * / 

MILES 0 25 50 75 loo MILES ,'/: : : : ) \ I 

1 • i 

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*- + + + + + + + + + + + •*- + * 

«V^Ï::xVxxxxxJ& \ ^ 

/(«MWSShl.-...-. • JÄL--J-I:»:S # ^ -~^Sl5:SSSfi?*'-j"* 

VijSL*- 

_^0^1 Dimaturu • 

/ 1 11 'É^ffl^jwfe^li 1 \PH 

i/^^DjWn 1 

S 4 

1 Gambe T Cza\ yf* \ / 

Kayunoéo|V 

2b, 

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Groundwater Areas ' 5 Chad sediments 

Availability of water from middle zone 

/PJ 

1 

2a 

Igneous and metamorphic rocks 

Cretaceous sandstones 

aquifer:- 

•'.''.• High-yield artesian aquifer 

. . Moderate-yield artesian (bl) 

2b Cretaceous shales g, sub-artesian aquifer (b2) 

\ J Main Road 

A Basaltic rocks Low-yield sub-artesian aquifer 

/ Railway _ . . H 1 1- * 5 Chad sediments ^ ^ «=» Hydrochemical front 

1 

10° 

D.O.S. (LR) 3064 V 


International Boundary 

+++++++ 

1 


+ 

3 Kerri Kerri sandstone Low-yield artesian aquifer 

6 Recent alluvium ,>* ^ ^ Direction of flow 

1 

•xv?V*- 

;-i/J+ 

Derived from information in Barber (1956) and Miller et al (1968) 


2° 

-10 

Printed by Ordnance Survey 

7/ 7(/5326/OS 

R

10° 

l4 'IT- 

12° 

,\ 

Mv 

/ 

MILES 0 

i—L_ 

fa/ •—•> 

*• + + + + + + 

10° 

D.O.S.(L.R.)3064T 


SCALE 1:3,000,000 

25 50 75 

Gombe 

ngolj). 

Main Road 

Railway 

_ International Boundary 

CATCHMENT AREAS 

\ 

12' 

'W 

ONu 

HowaV. 

/ '1 

>Song 

J_ 


K 

TEXT MAP II 

LEGEND 

LAKE CHAD DRAINAGE BASIN 

A Yobe river system 

B Damaturu river system 

C Kyauwo river system 

D Yedseram river system 

E El Beid river system 

BENUE RIVER DRAINAGE BASIN 

F 

Gongola and undifferentiated 

tributaries 

Hawal river system 

Anumma river system 

Benue and undifferentiated 

tributaries 

Tiel river system 

Kilunga river system 

Pai river system 

M Wase river system 

Lake Chad - Benue Divide 

_ . _• . — . —. Gongola watershed 

Other watersheds 

V \ \ \ \ \ \ ^ Areas with only local surface flow 

LAKE CHAD DRAINAGE BASIN 

The Lake Chad drainage basin is an internal drainage basin with a total area of 2 335 000 km 2 

(900 000 mi 2 ) (Gischler, 1967). It extends from the Hoggar and Tibesti mountains on the 

northern frontier of the Niger Republic to the Chad/Sudan frontier in the east and the highlands 

of the Chad/Congo divide in the south. In Nigeria the watershed of the Chad Basin 

runs from the Niger frontier north of Kano, south to the Jos Plateau (see Text Map 1) and 

then northeast to Potiskum and Damaturu before swinging southeast to Mubi and the Cameroon 

frontier. 1 660 000 km2 (64 000 mi 2 ) of the Chad Basin lie within Nigeria, of which 

106 300 km 2 (41 000 mi 2 ) are covered by the North East project. 

Ninety-five per cent of the water which flows into Lake Chad comes from the Chari and Logone 

river systems, which rise in the highlands in southern Chad and the Central African Republic 

and flow into Lake Chad from the southeast. The El Beid and Yedseram river systems rise in 

the Mandara Mountains and together supply about 4 per cent of the water to Lake Chad. The 

Yobe river system, whose upper reaches drain the Jos Plateau and the plains to the north of 

it, supplies less than 1 per cent of the total. Thus less than 5 per cent of the total 

inflow to Lake Chad originates in Nigeria. 

The major tributaries of the Yobe river system are the Jamaare which rises on the Jos 

Plateau and the Kano (subsequently the Hadejia) which rises in the highlands to the north of 

the Plateau and flows northwest as far as Kano before swinging northeast towards Lake Chad. 

The third tributary, the Komadugu Gana, rises further east on the Bauchi Plains. Records 

have been made at several stations on the Yobe river system (N. Nigeria Govt., 1963 and 1965) 

and its behaviour has been summarised in a report on the Lake Chad Basin within Nigeria 

prepared by the United States Department of the Interior (USAID, 1968). Virtually all the 

water is derived from seasonal rainfall on the Jos Plateau and the Basement plains west of 

the North East project area. In the project area itself there is very little surface flow, 

rainfall is largely balanced by evaporation and the Yobe river system as a whole is a losing 

one. The estimated total average annual runoff from the headwater tributaries is 

6 167 x108m 3 (5 000 000 acre ft) and probably not more than 1 850 x lOema (1 500 000 acre ft) 

flows past Gashua. The additional inflow to the Yobe from the Komadugu Gana is about 

986.8 x 10 e m 3 (800 000 acre ft per annum). At Damasak, 10 km (6 mi) below the confluence, 

the combined average annual yield is only about 986.8 x lOems (800 000 acre ft) and of this 

only about 444 x 10 e m 3 (360 000 acre ft) reach Lake Chad. Most of the loss is due to evapora 

tion, although there is some recharge of aquifers in the Chad Formation (see section on 

hydrogeology). 

The pattern of flow in the Yobe river system is closely related to the rainfall pattern in 

the highlands. The peak river stages in the Jos Plateau and on the Basement plains are in 

late August. As the streams flow northeastwards they flood the extensive old stream channels 

and depressions in the Yobe River Complex (see Text Map 2). Large areas are inundated west 

of Gashua, at the confluence of the Hadejia and the Jamaare, and in the vicinity of Geidam at 

the confluence with the Komadugu Gana. This widespread flooding retards the travel of the 

peak flow downstream. The peak flood reaches Hadejia in September, Gashua by mid-October, 

Geidam by November and Damasak by December. It does not reach Lake Chad until January. The 

average peak flow at Hadejia is about 1 981 mas (70 000 cusecs). This decreases to about 

283 mas (10 000 cusecs) at Gashua, to 65 m3s (2 300 cusecs) at Damasak and 40 m 3 s (1 400 

cusecs) at Yau (Yo) 20 km (12 mi) from the shores of Lake Chad. 

The flow decreases rapidly after the flood peak passes. Usually the flow is zero in the 

lower reaches of the river from April through to June. In years of high runoff a small flow 

of 0.28 -0.57 m3s (10 - 20 cusecs) may occur east of Gashua throughout the dry season.. Swamps 

and pools remain even in years of low runoff. The limited local runoff into the main river 

system does not materially affect the flooding as it is dissipated before the arrival of the 

flood peaks from the highlands further west. 

The main components of the Yedseram river system are the Yedseram itself, which rises in the 

Mandara Mountains east of Mubi, and the Ngadda which rises further west on the upland southeast 

of Damboa. North of Mubi many smaller tributaries of the Yedseram drain the western 

slopes of the Mandara range. The El Beid also rises in the Mandara range, but further east 

in the Cameroon Republic, and only a small part of its catchments lies in the project area. 

The Yedseram and El Beid river systems have a similar regime to the Yobe river system in that 

they depend on seasonal rainfall in the mountains and the upper reaches and that their lower 

reaches are regions of extensive flooding, high evaporation and net loss. 

77

The Yedseram and the Ngadda flow north from the Mandara range and the upland west of the 

Yedseram plains. They are in separate channels as far as Bama and Maiduguri where they 

breach the Bama Ridge. Thereafter they have no continuous channel and their flow is diffused 

in the extensive swamps and depressions of the Bama Deltaic Complex. Only the Yedseram 

crosses the Chad Lagoonal Complex and reaches Lake Chad with a distinct but far smaller 

channel (the Mabuli). The Ngadda has no outlet to the Lake. The total average annual runoff 

in the headwaters of the Yedseram system is about 1 233.5 x l0 8 m 3 (1 000 000 acre ft) of 

which only about 123.4 x 10 e m 3 (100 000 acre ft) reach Lake Chad (Raza, 1969). 

The streams which originate in the Mandara Mountains have their peak flows in August; but the 

rivers do not usually start flowing in the Maiduguri/Bama region until early August. 

The Yedseram at Bama has an estimated annual yield of 308.4 x 10 6 m3 (250 000 acre ft) between 

August and November, with a peak flow of 85 m 3 s (3 000 cusecs) in the middle of September. 

The river is usually dry by the end of November. The estimated annual yield of the Ngadda at 

Maiduguri is 246.7 x 10 e m 3 (200 000 acre ft) with a peak flow of 57 m 3 s (2 000 cusecs). Its 

flow is also confined to August - mid November with no dry season flow. The flow of the 

Ngadda at Maiduguri is however more uniform than the Yedseram at Bama. This is because Lake 

Alo, south of the Bama Ridge, stores the early runoff from the upper reaches. The average 

annual inflow to Lake Alo is about 431.7 x 10 e m 3 (350 000 acre ft) - 50 per cent more than 

the yield at Maiduguri. 

Between the Komadugu Gana and the Yobe in the north and the Yedseram river system in the 

south there is very little runoff. Several areas are flooded following heavy rain but virtually 

all the water is lost, mostly by evaporation. Water flows in the upper reaches of the 

Damaturu and the Kyauwo river systems immediately following the rains, but it does not flow 

beyond the line of the Bama Ridge and does not significantly affect the flow of the Ngadda at 

Maiduguri. 

The hydrological regime of the El Beid river system is very complex, partly because floodwaters 

from the Logone and Chari rivers flow into it. The main tributary of the El Beid 

river system in Nigeria is the Nasawa (or Goma) which drains the northern flanks of the 

Mandara range and breaches the Bama Ridge east of Bama. The El Beid flows between mid-July 

and April with a mean annual yield of 1788.6 x10 e m 3 ' (1 450 000 acre ft). There is a range 

863.5 x 10 e m 3 (700 000 acre ft) to 2 713.7 x 10 8 m 3 (2 200 000 acre ft) between low and high 

yield years (Raza, 1969). Hydrographs on the El Beid at Gambaru (on the road from Dikwa) 

indicate two peak flow periods; one in August related to rainfall in Nigeria and the Mandara 

Mountains in Cameroon and the second in December related to floodwater from the Logone and 

the Chari. 

The level of Lake Chad is closely related to the hydrological regime of the Chari and the 

Logone which together contribute 95 per cent of the total inflow. Lake Chad is highest in December 

and January, after which the water level falls until July. On average the lake receives a 

total runoff of 41 075.6 x lOem 3 (33 300 000 acre ft) and about 4 934 x 10 e m 3 (4 000000 acre 

ft) of rainfall per annum. It owes its existence to the balance between this water input and 

evaporation. Infiltration losses are thought to be negligible. Mean annual evaporation from 

the lake surface is 2 290 mm (90 in) with the highest mean monthly value of 250 mm (10 in) in 

May. The maximum recorded lake level is 284 m (932 ft); the lowest is 281 m (922 ft). With 

these changes in level the flooded area varies from a maximum of 25 000 km 2 (9 600 mi 2 ) to a 

minimum of 15 000 km 2 (5 800 mi2) (Raza, 1969). 

BENUE DRAINAGE BASIN 

The south of the project area is drained by tributaries of the Benue. The Benue itself rises 

further south and east in the highlands of central Cameroon. It flows from east to west 

along the southern border of the project area to join the Niger at Lokoja, west of Makurdi 

(see Text Map 1). The total area of the Benue drainage basin is 337 000 km 2 (130 000 mi 2 ) of 

which 233 000 km 2 (90 000 mi 2 ) are in Nigeria and 69 200 km 2 (27 000 mi 2 ) fall in the project 

area. The hydrology of the Benue river and its major tributaries has been investigated by 

NEDECO (1959). The regime is governed by high rainfall in the highlands in central Cameroon 

and in the Nigeria/Cameroon frontier region south of Yola; rivers entering the Benue from the 

north, from the North East project area, contribute less than 10 per cent of the total discharge 

into the Niger. 

78

In general throughout the North East project area the dissected and highland regions of the 

Benue drainage basin are characterised by high runoff and fast-flowing seasonal streams which 

feed larger slow-flowing rivers on the plains. These larger rivers contain water all the 

year round and have a weakly perennial flow. 

The Gongola is the largest tributary to join the Benue from the north and it drains twothirds 

of the Benue basin within the project area. It rises on the Jos Plateau and flows 

northeast across the Bauchi Plains before cutting through the Kerri Kerri Plateau and swinging 

abruptly south at Nafada to flow through the Gongola Valley and join the Benue at Numan. 

2 major tributaries of the Gongola rise on the Biu Plateau. The Anumma flows north from Buni 

and then turns abruptly southwest to join the Gongola at Nafada; the Hawal which is the 

larger of the 2, flows northeast from Biu and then swings south and southwest to join the 

Gongola north of Snellen. Minor tributaries flow direct to the Gongola from the northern 

half of the Kerri Kerri Plateau and within the Gongola Valley itself. Water flows in the 

Gongola and the Hawal throughout the year, but with a considerable seasonal variation in discharge. 

During the dry season there is standing water or water can be obtained from the sand 

bed of the Anumma and from several of the smaller tributaries but flowing water is restricted 

to the period immediately following the rains. Most of the water in the Gongola originates 

on the highlands of the Jos Plateau; the average annual discharge into the Benue is 8017.8 x 

10 6 m 3 (6.5 million acre ft) of which the Hawal contributes only 925 x 10 8 m 3 (750 000 acre ft); 

there are no records for the other tributaries. The Gongola reaches its maximum flow in 

September when the average annual discharge for 1955-7 was approximately 1670 m 3 s (59 000 

cusecs) (NEDECO, 1959); during the period of minimum flow, from December to the end of May, 

discharge of the Gongola falls as low as 5.7 m 3 s (200 cusecs) and on the Hawal to as little 

as 0.28 m 3 s (10 cusecs) (Raza, 1969). 

West of the Gongola Valley the southern part of the Kerri Kerri Plateau and the Benue Valley 

west of Kaltungo is drained by the Pai. To the east of the Gongola the Gaanda Hills and the 

southern margin of the Uba Plains are drained by the Kilunga and further east the Tiel drains 

the southern margin of the Mandara Mountains. As with the Gongola and its tributaries these 

rivers are seasonal. 

In the Benue Valley the main feature of the flow pattern of the Benue is the large area of 

the floodplain between Numan and Lau which is flooded annually. This flooding has the effect 

of both merging the twin peak flood at Numan to a single longer peak further downsteam, and 

of delaying the downsteam peak flood. At Yola the mean annual yield is 23 437 x 10 e m 3 (19 

million acre ft) with discharge maxima between 4245 and 5660 m 3 s (150 000 and 200 000 cusecs) 

in September and in October. At Lau the maxima are less distinct and a flow of between 4 245 

and 5660 m 3 s (150 000 and 200 000 cusecs) is maintained from early September until late in 

October. At Augwan Taru (downstream from the confluence with the Pai) the mean annual yield 

is about 37 005 x 10 e m 3 (30 million acre ft) with a maximum of more than 5660 m 3 s (200 000 

cusecs) which lasts from mid-September until late in October. 

GROUNDWATER 

The distribution of groundwater in northern Nigeria has been described by du Preez and Barber 

(1965) and there are several reports presenting the results of investigations of the artesian 

aquifers within the Chad Formation. 

Du Preez and Barber recognised 10 groundwater areas in northern Nigeria, 6 of which occur 

within the area covered by the present investigation. Each is closely related to 1 of the 

major groups of rocks described in the geology section. The hydrological characteristics of 

each of these groundwater areas are summarised below; their distribution is shown on Text 

Map 10. 

Area 1 Igneous and Metamorphic Rocks, Mainly of the Basement Complex 

Over most of the area underlain by the Basement Complex there is a thin discontinuous mantle 

of weathered rock with sedentary soils, colluvial material or ironpan. The average thickness 

of this mantle is about 15 m (50 ft) but in some areas it extends to depths of 60 m (200 ft). 

The finer grained rocks are generally more resistant to weathering than the more coarsely 

grained types. Joints and fractures are common and vary greatly in their depth and lateral 

persistence. They form both tight cracks and open fissures and in some areas the rocks have 

been faulted with associated crush zones. The joints probably do not extend beyond 90 m 

(300 ft); larger fractures and fault zones go deeper. In general, joints are better 

developed in the granites and quartzites than in the gneisses, migmatites and schists. 

79

Groundwater occurs in these igneous and metamorphic rocks either in the weathered mantle or 

in the joint and fracture systems in the unweathered rocks. The presence of groundwater 

therefore depends on whether the mantle is sufficiently thick and extensive to provide a 

reservoir, or whether joints and fractures are present in the fresh rock. Thick colluvial 

deposits provide good reservoirs, but apart from this the Basement Complex rocks generally 

form a poor source of groundwater. The decomposed mantle is usually too thin to harbour 

large quantities of water and is usually too clayey to be highly permeable. The joints are 

normally too poorly developed to compensate for the inadequacy of the weathered zone overlying 

them. The average depth to the watertable is 36 m (120 ft). Wells, if carefully 

sited, will normally provide an adequate supply for village communities. The average yield 

from wells in Basement rocks is 3 650 litres (800 gal) per hour. 

Small springs and seepages are common in areas underlain by rocks of the Basement Complex. 

They give rise to small swamps and moist areas in many localities and in some places they 

coalesce to form streams. Throughout groundwater area l seepage springs are the main source 

of perennial surface water. 

Area 2 Cretaceous Sedimentary Rocks 

The principal water-bearing Cretaceous strata are the sandstones of the Bima, Yolde and Gombe 

Formations. Where these strata outcrop groundwater normally occurs under watertable conditions. 

Clay lenses which occur confined within the sandstones give rise to localised 

pressure water. The actual groundwater conditions differ in different areas because of the 

varying relations of these sandstones to the remaining, predominantly argillaceous strata. 

The permeability of the Bima Sandstone is generally low because of interstitial clay derived 

from decomposed feldspar; the Sandstone is however believed to contain large reserves of 

available groundwater. The rocks of the Yolde Formation vary considerably in lithology and 

texture and their water-bearing properties are gradational between those of an aquiclude 

and aquifer. High-yielding pressure aquifers have been proved at several horizons and considerable 

sub-artesian rises have been recorded. 8 boreholes in the Gombe area have yielded 

from 8 200 to 18 200 litres (l 800-4 000 gal) per hour. The Gombe Sandstone contains both 

aquifers and aquicludes and contains pressure water confined by intra-formational shale 

horizons. Sub-artesian yields between 12 700-24 500 litres (2 800-5 400 gal) per hour have 

been obtained from the base of the Formation. The Gongila Sandstone also contains pressure 

water where it is overlain by the Fika Shales. Limited supplies of water are obtained from 

the Dukul and Jessu Formations, both of which contain porous and permeable horizons. 

The other Cretaceous Formations do not generally form good aquifers and the limited groundwater 

which they do contain is often highly mineralised. The impermeable clays and shales 

yield negligible amounts of water. The limestones do not usually form aquifers; the thin 

sandy lenses contain water, but yields are small. The hydrological importance of these 

sediments is that they confine water in the underlying Bima and Yolde Sandstones. Considerable 

quantities of groundwater also occur in the colluvial sands which surround the Lamurde 

anticline and are underlain by clays and shales (Klinkenberg, 1967). 

Area 3 Kerri Kerri Sandstone 

Groundwater occurs mainly under watertable conditions in the Kerri Kerri Sandstone. The 

saturated portion of the Formation contains a large quantity of water but much of this is not 

readily exploitable because interstitial clay and silt reduces its permeability. However 

there are some good-quality aquifers. Occasional clay lenses give rise to perched aquifers 

in some localities. Confined water occurs in some places where the Kerri Kerri is overlain 

by impervious sediments of the Chad Formation north of the outcrop. 

Dousse (1969) has mapped the watertable in the Kerri Kerri Formation. The depth varies 

widely ranging from 0-180 m (0-600 ft) below the surface. The slope of the watertable is 

closely related to the slope of the land surface, although the watertable contours are less 

steep. The irregularities in the steepness and direction of the slope of the watertable are 

caused by both vertical and lateral changes in the permeability of the rocks and by the 

thickness of the water-bearing strata. Groundwater ridges coincide with the major stream 

channels and the streams supply water to the permanent groundwater by influent seepage. The 

watertable beneath and adjacent to the streams is usually near the surface, but between the 

streams the depth to the watertable increases rapidly. The gradient ranges from 0.9-10.7 m 

per km (3-35 ft per mi) and averages approximately 3.7 m per km (12 ft per mi) (Dousse 1969). 

Gradients of 12.2-21.3 m per km (40-70 ft per mi) are common in the western part of the area; 

this is a reflection of the steep slope of the land surface and probably also reflects an 

increase in permeability of the water-bearing sediments. 

80

In areas with a comparatively dense drainage pattern the watertable is usually within reach 

of hand-dug wells but the watertable is generally too deep where the drainage pattern is 

sparse; in such areas the groundwater can only be exploited by drilled wells. Over most of 

the Potiskum Plain and near the Gongola river the watertable can be reached by hand-dug wells 

which are seldom deeper than 90 m (300 ft). North of the railway the watertable lies about 

150 m (500 ft) below the surface and hand-dug wells tap only perched aquifers. In some 

places in the southwest of the Kerri Kerri Plateau the watertable is deeper than 150 m 

(500 ft). 

Some recharge occurs along the line of the Gongola river because of the permanent underflow 

that originates in the underlying Basement Complex rocks of the Bauchi Plains, to the west 

of the Kerri Kerri Plateau. Away from the Gongola virtually all the recharge is from rain. 

The maximum rise in the watertable occurs towards the end of July and early in August, during 

the heaviest rains, when rises of up to 10 m (33 ft) are common in shallow wells; deeper 

wells show comparable, but slower rises. The levels begin to fall soon after the end of the 

rainy season. 

East of Potiskum the watertable intersects the ground surface. There have been remarkable 

rises in the watertable in this area in recent years and new springs, seepages and perennial 

streams and lakes have been formed. Water levels in wells have also risen substantially and 

rises of up to 50 m (160 ft) have been recorded. Carter and Barber (1958) suggested that 

this was a result of deforestation following increased settlement and cultivation. Later 

work by Dousse (1969) has confirmed this hypothesis and shown that the increased runoff due 

to deforestation, although important during the rainy season, is smaller than the increase 

in percolation to the watertable. 

Area 4 Basaltic Rocks 

In general the basalts are satisfactory aquifers and considerable amounts of groundwater 

occur in weathered zones both near the surface and between successive lava flows. Water also 

occurs in fissures and fractures but it is not found in the massive unweathered rock 

(du Preez, 1949). Groundwater may also occur at the base of the volcanic succession trapped 

in the underlying weathered rock. Numerous springs and seepages emerge along the margins of 

the lava flows. They vary widely in yield and some flows are large and perennial. 

The amount of water provided by the basalts depends on the size of the rock mass and on the 

degree of weathering; thus the Biu and Longuda basalt plateaux are more significant sources 

of groundwater than the smaller basaltic areas where the rocks have only local hydrological 

significance. In many places on the Biu Plateau considerable amounts of water occur in the 

weathered basalt, although there is much seasonal variation in the level of the watertable. 

The pyroclastic rocks north of Biu are highly porous and they give rise to several springs. 

Further east on the Biu Plains the basalts are generally thin and contain far less groundwater. 

Most of the water in the area is derived from weathered Basement rocks beneath the 

basalt. On the Longuda Plateau groundwater occurs both at the base of the lava sequence and 

in weathered zones between successive flows. 

Area 5 Chad Formation 

Groundwater is found under watertable or semi-confined conditions in the whole of the 

saturated section of the Chad Formation in the west and south of area 5, and in the 

saturated portion of the top 60-90 m (200-300 ft) of the Formation in the northeast. It 

occurs in lenses of gravel, sand and silt. Lines of equal depth to the watertable reveal a 

complex pattern of low ridges and troughs, the more important ridges occurring below the 

larger stream courses. This suggests that the ridges are formed by influent seepage from the 

stream channels. Unconfined aquifers are the most common source of supply tapped by wells 

and boreholes in the western and southern part of the area. There are also occasional semiconfined 

aquifers in the watertable and some isolated sand lenses within the thick clays 

contain pressure water. In the northeastern part there are 3 zones of confined aquifers 

which provide most of the borehole supplies. The middle zone occurs over a wide area between 

Damaturu and Lake Chad (see Text Map 10). 

The first published account of the hydrology of the Chad Formation in Nigeria was by Raeburn 

and Jones (1934) who were the first to suggest it might contain artesian water. The first 

artesian borehole was drilled by the Nigerian Geological Survey in 1946 and regional exploration 

for artesian aquifers began in 1955. The results of production drilling were summarised 

by Barber (1965) who described the distribution of pressure water in the Chad Formation. 

Subsequently Miller et al. (1968) investigated the groundwater hydrology further with special 

emphasis on the flow life of the artesian system. The hydrology of the whole of the Chad 

Basin has been under a joint UNESCO/FAO investigation (Gischler, 1967) in an attempt to 

81

assess the recharge potential more fully. Text Map 10 shows the western limit of pressure 

water derived from the Chad aquifers and also summarises the availability of artesian water 

from the middle zone aquifer. 

Below Maiduguri Barber and Jones (1960) recognised 3 water-bearing zones in the Chad 

Formation which they called the upper, middle and lower zones. The middle and lower zones 

yield water under artesian conditions, while water has to be pumped from wells in the upper 

zone. At Maiduguri the upper zone aquifer occurs between 30 and 90 m (100 and 300 ft) below 

the surface. It consists of lenses of fine to coarse sand intercalated with clays and silts. 

Individual lenses are not thick and rarely exceed 4.5 m (15 ft). Elsewhere a similar series 

of sand and clay layers 15-180 m (50-600 ft) thick occur above the middle zone and these have 

been grouped with the upper zone at Maiduguri. The variations in depth to water in the upper 

zone show that groundwater highs occur along the edge of Lake Chad and along all the major 

rivers. A marked groundwater low extends from Gubio to a few kilometres northwest of 

Maiduguri. This suggests that water in the upper zone originates from Lake Chad and from the 

river systems, and that in the aquifer it flows away from the lake and towards the interstream 

areas. Recharge to the upper zone by this process depends on the seasonal flow of the river 

systems. The amount of recharge is not known. The withdrawal rate from this zone is likely 

to increase in the future and close attention will have to be given to the construction and 

spacing of boreholes if the balance between withdrawal and recharge is to be satisfactorily 

maintained. The lower zone aquifer has been identified between 420 and 480 m (l 380 and 

1 580 ft) below the ground surface at Maiduguri but it seems to have a very limited lateral 

extent and has not been recorded elsewhere. 

The middle zone of aquifers is the most important and the most extensive, and has a proved 

lateral extent within Nigeria of about 52 000 km 2 (20 000 mi 2 ). It is known to extend north 

into the Niger Republic and is believed to extend east into the Cameroon Republic. The zone 

varies in thickness from a very thin layer to over 120 m (400 ft), but over most of northeast 

Nigeria it is thought to be between 60 and 90 m (200 and 300 ft) thick. The depth from the 

surface to the top of the zone in the proved area ranges from 75-375 m (250-1 230 ft). The 

aquifers within the zone consist of fine to coarse sand and occur as interconnected lenses 

intercalated with clays and sandy clays. Surface flows can be obtained from the zone in 

approximately 31 000 km 2 (12 000 mi 2 ) of Bornu and Dikwa emirates. The highest positive head, 

recorded near Lake Chad, is 21 m (70 ft) above the ground surface; in some parts of the subartesian 

area the pressure surface is more than 60 m (200 ft) below the ground surface. 

The recharge potential of the middle zone aquifer is not fully understood. Barber (1965) 

showed that there are 3 areas of intake to the middle zone and that the main directions of 

flow are towards the Mongonu area; the Damaturu/Magumeri and Bama/Gulumba areas form subsidiary 

foci (see Text Map 10). Present evidence suggests that, although there is a large 

amount of water stored in the middle zone, the amount of water flowing through it is relatively 

small. Miller et al. (1968) concluded that no significant amount of recharge reaches 

the middle zone in Nigeria. At the rate of withdrawal in 1965 (5.68 million litres or 1.25 

million gal per day) they estimate that artesian water would continue to flow for at least 

30 years from the moderate and high-yield areas of the middle zone at a rate of 2 273 litres 

(500 gal) per hour with boreholes 8 km (5 mi) apart. With boreholes 16 km (10 mi) apart, 

flows of at least 22 730 litres (5 000 gal) per hour could be maintained in the high-yield 

areas. In the low-yield areas artesian flows of 455-910 litres (100-200 gal) per hour could 

be maintained with boreholes 8 km (5 mi) apart. 

Area 6 Recent Alluvium 

Groundwater in the recent alluvial deposits is mainly replenished from the surface flow of 

the streams. With seasonal streams the quantity of water and the length of time that the 

water is retained in the alluvium after surface flow ceases depends on the porosity, 

permeability, thickness and extent of the alluvium and the hydraulic gradient. In many 

streams water is retained in the alluvium throughout the year and these reserves can constitute 

important sources of groundwater. Groundwater may occur in river alluvium under pressure, 

but this is usually a very local phenomenon. 

GROUNDWATER QUALITY 

The chemical quality of groundwater is almost as important as its quantity, particularly if 

it is to be used for industrial purposes or for irrigation. De Preez and Barber (1965) have 

summarised existing information on the chemical quality of the groundwater derived from each 

of their Groundwater Areas and Barber (1965) has described the quality of the water from 

each of the 3 pressure aquifers in the Chad Formation. Most of the groundwater is of relatively 

high quality; water unsuitable for human consumption is rare and hardly any sources 

are unsuitable for animal consumption. Many of the sources of groundwater are immediately 

82

suitable for irrigation, and most could be used for irrigation of selected plants, providing 

leaching precautions and chemical corrections were made to allow for the interaction of the 

dissolved salts with the particular range of soils. 

Apart from possible pollution by nitrates, the Basement Complex rocks provide good drinking 

water. The waters generally contain less than 200 ppm of dissolved solids and are either of 

the calcium or sodium bicarbonate type (du Preez and Barber, 1965). Waters from the Bima 

Sandstone and the Yolde Formation in area 2 are sodium or calcium bicarbonate types with 

little or no sulphate. Apart from some samples with excessive concentrations of iron, they 

are good drinking waters. The more saline, sodium-rich waters may have only limited applications 

for irrigation; hardness, alkalinity and iron concentration may limit their industrial 

potential. A sample from the Gombe Sandstone at Gombe was of the calcium bicarbonate 

type and was low in dissolved solids. The concentration of iron was high; otherwise it was 

good-quality drinking water suitable for irrigation under most conditions. Analyses of 

groundwater for the Kerri Kerri Sandstone (area 3) indicate water of low salinity of the 

sodium-calcium bicarbonate type. Nitrate in some samples indicates probable pollution; 

unpolluted, these are good-quality drinking waters and are suitable for irrigation and for 

most industrial purposes. Analyses of only 1 sample are recorded from the Biu Plateau; it is 

a good-quality drinking water but industrial applications may be limited by hardness, alkalinity 

and salinity. 

Waters from the western half of the Chad Formation (area 5) are of the calcium-sodium bicarbonate 

type; they are low in dissolved solids and slightly alkaline. Apart from the pollution 

hazard, they are good drinking waters and are suitable for irrigation under most conditions. 

They are also suitable for many industrial processes. The waters from the upper zone 

of confined aquifers are of the sodium bicarbonate'type (Barber, 1965). They are silicarich, 

low in dissolved solids and slightly acidic. They are excellent drinking waters and 

are suitable for both industry and irrigation. Waters from the lower zone are low in total 

solids and are of the sodium bicarbonate type. They contain free carbon dioxide and are 

slightly acidic. They are good drinking waters and can be used for irrigation on all but 

clay soils. They are suitable for most industrial purposes, though high in iron content. 

Waters in the middle zone range in salinity from 194 to 1 065 ppm. They are sulphatebicarbonate 

or bicarbonate-sulphate types; free carbon dioxide is always present and these 

waters are therefore slightly acidic. Total alkalinity ranges from 98 to 292 ppm and total 

hardness from 18 to 320 ppm. Within this range Barber (1965) recognises 3 groups of groundwater. 

Sulphate with subordinate bicarbonate waters occur north of Gudumbali; bicarbonatesulphate 

waters predominate between Gudumbali and Dikwa; east of Dikwa bicarbonate waters 

with only a little sulphate predominate. The zones along which these waters meet are marked 

by chemical interfaces (see Text Map 10). All the waters from the middle zone are good or 

fairly good drinking waters, although high iron and manganese concentrations may need to be 

reduced if the supply is to be piped. Irrigation with these waters is usually difficult, and 

because of either corrosive effects, high salinity, hardness and alkalinity, or excessive 

concentrations of iron and manganese, they have only limited industrial applications. 

Groundwaters from river alluvium are of the calcium bicarbonate type and are low in total 

dissolved solids. They are suitable for most uses. One disadvantage is that these shallow 

water supplies are liable to pollution where waste disposal is not controlled. 

83

10" 

NgUTl 

D.O.S.(L.R.)3064Y 


MILES 0 

AREAS COVERED BY 

RECONNAISSANCE SOIL SURVEYS 

12* 

SCALE 1:3.000.000 

IcungoO 

25 50 75 

_ _ _ ^ ^ _ Main Road 

i t i Railway 

+ + •+• + + + International Boundary 

12 

H 0 waK 

5 Song 

,13 

II 

Mongonu ( 

10 

TEXT MAP II A 

Map 

Reference 

Area 

Year 

Authors *£,& 

Year of 

Publication 

1 North-eastern Bornu 1959-60 G.M. Higgins. D.M. Ramsay. 

R.A. Pullan & P.N. de Leeuw 

14 I960 

Nfuru-Hadejia-Gurrnel 1961 R. A. Pullan IB 1962 

3 Axare 1961 R.A. Pullan 19 1962 

4 Poti»kum-Damaturu I9S9 W. A. Hope 20 1963 (provisional 

edition only) 

5 Middle Gongola 1958-61 K. Klinkenberg. P. R. Tomlinson, 

G. M. Higgins & P. N. de Leeuw 

21 1963 (provisional 

edition only) 

6 Lau-Kaltungo 1964-66 K. Klinkenbert 36 1967 

7 Lamewa 1966 G.M. Higgins 38 (draft only) 

8 Maiduguri 1967 D.M. Carroll 40 1970 

9 Gulumba 1967 R.A. Pullan 41 1969 

10 Kirawa 1967 R.A. Pullan 42 1970 

II Biu-Mubi 1966 D. M. Carroll & W. A. Hope 43 1970 

12 Goniri 1967 K. Klinkenberg (inpr eparation) 

13 Song 1967-68 W.A. Hope (inpr eparation) 

12° East of Greenwich 14" 

84 

Drawn and photographed by Directorate of Overseas Surveys, 1970

INTRODUCTION 

D M Carroll 

SOILS 

by 

and K Klinkenberg 

The soil map at 1:1 000 000 (Map 3)presented with this report is largely based on reconnaissance 

surveys carried out by the Soil Survey Section of the Institute for Agricultural 

Research, Samaru, with assistance by the Department of Geography, University of Liverpool, 

and by the Land Resources Division of the Overseas Development Administration, Foreign and 

Commonwealth Office. Aerial photographs were used in drawing soil boundaries for the 

unsurveyed areas, enabling much of the information collected during the reconnaissance 

surveys to be extrapolated over the areas with less detailed information. 

The survey cover published or in the press as Soil Survey Bulletins of the Institute for 

Agricultural Research is shown in Text Map IIA. In this report full use is made of the data 

published in these bulletins and also of unpublished material held in the Soil Survey Office. 

In all more than 1 100 soil profiles were described and analysed. The work of the many 

people who made the surveys is acknowledged, but responsibility for the correlation and final 

classification remains with the authors. Exchanges with pedologists from neighbouring francophone 

territories have taken place, which have been particularly helpful, as the classification 

for the map is based upon the French system. 

85

Figure 7 Generalised soil pattern 

00 * * x x * x X x ** VV^VÏ'WKS*»* 

Rock 

outcrops 

Rocky 

soils 

Shallow and 

deep sandy soils 

Well drained 

loamy soils 

Poorly drained 

loamy-clayey soils 

Topography Very steep Steep Undulating Oentle Nearly flat Flat 

Profile development No No No Weak Moderate Oood 

Soils with 

lronpan 

Clay content Very low Low Moderate Moderate-high Moderate 

Mottles No No No No No-few Common-many Common-many 

Ironconcret. No No No No-few Few Common Many 

Llmeconcret. No No No No No Locally Locally 

D.O.S 3099 G

Soils in Relation to Soil-forming Factors 

Forty units are shown on the soil map; each has its own particular pattern, often of a 

catenary nature. 'Catena' is a name given to an assemblage of soils occurring in a natural 

order in relation to the slope and that order is found over most of the unit. Topography has 

an important bearing on several soil-forming processes. 

Some of these processes and the resultant soil patterns are illustrated in Figure 7 which 

gives a schematic view of the different topographic conditions that exist on rocks such as 

granite and the mineralogically similar Bima Sandstone. 

In hilly areas the rock is mainly subject to physical weathering; the resulting debris is 

moved downslope by gravity and by rainwater. This disintegration continues and the weathering 

products are gradually moved further down the slope. The hills are therefore often 

surrounded by areas of sandy wash. These wash soils have little or no differentiation within 

the profile and they contain very small amounts of clay because the clay is normally carried 

away by water moving laterally through their profile. 

Further away from the hills, where slopes become gentler, the soil material is normally 

developed in situ. Here clay is leached from the upper parts of the soil and redeposited in 

subsoil horizons. Part of the clay in these horizons may also be derived from higher up the 

slope. 

The role of groundwater becomes increasingly important when the slopes become gentler. Soils 

in which groundwater is present for some time of the year are grey or pale in colour and are 

normally mottled. Better-drained soils are often brown or reddish. Groundwater is also an 

important agent in the vertical and lateral movement of clay and some of the chemical constituents. 

Soils of lower slopes and plains are often richer in clay, calcium carbonate and 

iron concretions than are upper slope soils. Although this sequence refers specifically to 

particular geological conditions, under different circumstances some of the important 

features are often found again. These are particularly: 

1. increasing clay content downslope; 

2. colour changes from red and brown to grey, downslope; 

3. accumulation of iron in lower-slope and flat areas; 

4. accumulation of calcium carbonate in lower-slope soils. 

The pattern shown in the diagram is always subdivided into several mapping units, the composition 

of which depends only on how the different components occur together in the terrain. 

Soils with ironpan, for instance, occur only on old, stable, land surfaces, such as those 

around Gombi and Askira. Units with hill and wash soils are almost absent from the northern 

part of the area, because only unconsolidated sediments of the Chad Formation occur here. 

The soils of the dunefield, which extends over a large part of the Chad Formation, also have 

a catenary arrangement similar to that already described: colour changes and 

increases in clay and calcium carbonate downslope. In relatively flat areas, where the runoff 

is naturally slow, poorly drained soils predominate. 

Important differences from the schematic outline shown are caused by differences in parent 

material. Soils formed from basalt have a similar arrangement, but they tend to be richer in 

clay and organic matter, while soils with iron concretions are infrequent and ironpan is 

completely absent. 

The Kerri Kerri Formation consists largely of very thick permeable sandstone deposits and 

poorly drained soils are almost absent. The soils are chemically poor, because the material 

has been subject to several cycles of weathering in the past. 

The shales in the Gongola and Benue Valleys and some lacustrine clays near Lake Chad are rich 

in the clay minerals of the montmorillonite type. The swelling and shrinking properties of 

this mineral have a strong influence on soil properties: the soils show deep, wide cracks 

during the dry season and the soils have little or no vertical differentiation. 

Climate is, with topography and geology, one of the most important soil-forming factors. 

Over the larger part of the area rainfall is sufficient to allow for a downward movement of 

clay and other materials, while most soluble salts are completely removed through the drainage 

system. Rainfall gradually decreases northwards and below 500 mm (20 in) the leaching 

87

of clay becomes very small. In the far north the rainfall is not sufficient for the development 

of a complete drainage network and water is found only in local depressions, where salts 

accumulate by evaporation. Calcium carbonate and sodium salts occur frequently in this part 

of the project area. If sodium ions are present in quantity, they may have a harmful effect 

upon the soil structure. 

The remaining soil-forming factors, time and biotic influences, are of relatively less 

importance in North East Nigeria. In recent sediments, such as riverine alluvium, no soil 

profile development has yet taken place, while on some older land surfaces sufficient time 

has passed to allow for the formation of an ironpan. Vegetation has contributed to soil 

formation particularly on the fringes of Lake Chad, where organic deposits occur. The 

activity of man has in several cases accelerated erosion and thus reduced the soil depth. 

CLASSIFICATION 

Principles 

The classification adopted is based upon that used by pedologists in neighbouring francophone 

countries (Aubert, 1964; 1965). The French system is followed as closely as possible, but in 

1 or 2 cases new categories are introduced to accommodate particular soils occurring in the 

project area. 

The French classification is largely based on the type and degree of profile development. 

Important parameters taken into account at a high level of classification include cation 

exchange capacity, base saturation, distribution of clay, amount and distribution of organic 

matter, sodium content and pH, as well as the occurrence of concretions. Soil depth, texture 

and colour are properties used at lower levels of the classification. 

Klinkenberg and Higgins (1968) discussed D'Hoore's legend (1964) of the soils map of Africa, 

as far as it applies to the northern parts of Nigeria.' In that legend a differentiation 

based on parent material was made at high level, because information on other aspects was 

insufficient. In the present report parent material is of intermediate importance in the 

classification. Soils separated at high levels of the classification may therefore occur 

together on 1 parent material. 

In the French classification classes are recognised by the mode and intensity of evolution. 

The classes are divided into sub-classes on differences in pedo-climate, while the subclasses 

are divided into groups on the basis of the presence or absence of certain diagnostic 

horizons (D'Hoore in Moss, 1968). Table 4 shows the parts of the classification relevant to 

North East Nigeria. It will be noted that sub-groups are shown only for the Leached 

Ferruginous Tropical Soils, emphasising the importance of this group of soils in the project 

area. 

Raw Mineral Soils (R) i 

This class consists of rock outcrops and debris derived from them. D'Hoore (in Moss, 1968) 

would call most of these 'non-soils' . The major characteristic is the almost complete lack 

of soil development. As this class mostly occurs in steep areas, weathering products are 

rapidly removed. 

Weakly Developed Soils 

1. Soils of erosion (We) These very shallow soils are often stony or rocky and have 

little or no profile differentiation. They are often developed on steep slopes and overlie 

solid rock within 30 cm (12 in) of the surface. Soils of this group are formed on granite 

of the Basement Complex, on sandstone, on basalt or on ironpan; they are never found over 

shales or unconsolidated sediments. They characteristically occur on eroded upper slopes in 

conjunction with Raw Mineral Soils or Non-Leached Ferruginous Tropical Soils, but they are 

not sufficiently extensive to be mapped separately. 

2. Soils of deposition These soils are usually coarse-textured and often retain their 

original sedimentary stratification. Profile development is confined to a small accumulation 

of organic matter at the surface. They are found on a wide range of unconsolidated parent 

materials: on aeolian sands, on pediment deposits and on riverine, deltaic, lacustrine or 

lagoonal alluvium. 

In alluvial areas the Weakly Developed Soils are normally associated with Hydromorphic Soils 

which form over the finer-grained deposits; in the north they also occur with Halomorphic 

88

TABLE 4 The main elements of the French soil classification 

Class Sub-class Group Sub-group 

Raw Mineral Soils Non-climatic Erosion 

Weakly Developed Soils Non-climatic 

Erosion 

Vertisols 

Topomorphic 

Isohumic 

Soils 

Lithomorphic 

With saturated 

exchange complex 

Deposition 

Semi-arid Brown Soils 

Mull Soils Tropical Eutrophic Brown Soils 

Sesquioxide Soils Ferruginous Tropical Soils 

Non- or Weakly Leached 

Halomorphic Soils 

Hydromorphic Soils 

Organic 

Mineral 

Normal 

Note: The units shown in italics are relevant to the project area. 

Leached Without concretions 

With concretions or pan 

Hydromorphic 

on poor materials 

Vertic

Soils. Local alluvium is found throughout the area, but it can rarely be shown on smallscale 

maps. 

On pediments there is a gradual transition from Weakly Developed Soils to Non-Leached 

Ferruginous Tropical Soils. The soils of the dunefield in the extreme north of the area have 

a very low clay content, which is reflected in their poor profile development. Visiting 

French pedologists (Gavaud, Bocquier and others) regard some of these soils as transitional 

between Weakly Developed Soils and Semi-arid Brown Soils. On the soil map they are indicated 

by the symbol Wa. 

Vertisols 

The Vertisols are fine-textured soils with coarse prismatic or blocky structure; they are 

generally dark in colour. The soil shrinks and swells seasonally and large cracks develop 

during the dry period; surface soil is moved down the cracks, causing a markedly homogeneous 

profile. At a depth of 100-120 cm (3-4 ft) which approximates to the depth of regular wetting 

and drying, the soil peds are normally polished and grooved; this phenomenon, known as 

'slickensides' is typical of the Vertisols. The soil surface may have a wavy 'gilgai' microrelief. 

These distinctive properties are caused by the high content of expansible clay in 

these soils. 

The Vertisols often have a slightly to strongly alkaline reaction, although slightly acid 

soils are also found. Most of the alkaline soils contain calcium carbonate concretions and 

some soils have gypsum crystals. Although the Vertisols are generally dark-coloured, their 

content of organic matter is low (0.3-1.5 per cent organic carbon). These soils contain more 

than 30 per cent clay and have a cation exchange capacity in excess of 30 meq per cent soil. 

They are rich in bases, particularly calcium and magnesium. Their sodium content is often 

high, but the exchange complex is only rarely more than 10 per cent saturated with this ion. 

The class of the Vertisols has recently been reviewed by Dudal (1965). They develop only in 

fine-grained parent materials under conditions of poor internal and external drainage where 

large quantities of bases can accumulate. They form in areas with semi-arid to sub-humid 

climates where the rainfall is of a seasonal nature and the total precipitation is normally 

between 500 and 1 000 mm (20 and 39 in). The associated vegetation is often tall grassland 

or Acacia savanna woodland. . 

Two sub-classes are recognised: Topomorphic and Lithomorphic Vertisols. 

1. Topomorphic Vertisols (Vt) These soils are formed in flat areas without good 

external drainage, where the pedo-climate is wet for much of the year. Their main occurrence 

is on fluvial deposits north of Numan and on lacustrine deposits to the south of Lake Chad. 

They are nearly always very dark in colour and they are sometimes mottled. They gradually 

merge with Hydromorphic Soils. 

2. Lithomorphic Vertisols (VI) These soils are mainly developed from shales of the 

Cretaceous marine facies on more or less undulating terrain. As they occur on gentle to 

moderate slopes, they have a better external drainage than the Topomorphic Vertisols and 

their colours are not quite so dark. 

Transitions between Lithomorphic Vertisols and the Hydromorphic sub-group of the Leached 

Ferruginous Tropical Soils are known to occur. In areas with rapidly alternating beds of 

sandstone and shale the soil pattern in which the Vertisols occur can be extremely complex. 

Isohumic Soils 

Only 1 group of this class is found in North East Nigeria: Semi-arid Brown Soils. 

This group is characterised by a homogeneous and deep penetration of organic matter. The 

total amount is often quite small and probably derived from decaying roots, and the associated 

sparse vegetation contributes very little surface litter. The exchange complex is 

saturated with calcium and the soils often contain calcium carbonate concretions or crusts. 

Many of the soils show an increase in clay content with depth, not as a result of leaching, 

but by new clay formation. In many cases the soil has well developed blocky or prismatic 

structure. 

The distinction between Semi-arid Brown Soils and Non-Leached Ferruginous Tropical Soils is 

not very clear in the literature. Klinkenberg and Higgins (1968) mapped most of the soils in 

the Damaturu area as Subarid Brown Soils, but visiting French pedologists have indicated that 

90

most of these soils are better classified as Non- or Weakly-Leached Ferruginous Tropical 

Soils, mainly because they show some translocation of iron in the profile. 

In the present report only soils which combine the absence of gley with the presence of 

calcium carbonate assumulation are considered as Semi-arid Brown Soils. They occur locally 

in depressions in the Damaturu area and are somewhat more frequent in the Hadejia area. The 

carbonate accumulation is normally in the form of concretions, but pseudomycelia and crusts 

are also seen. 

Gavaud (personal communication) regards the soils of the dunefield in the extreme North East 

as transitional between Semi-arid Brown Soils and Weakly Developed Soils, mainly because of 

their uniform brownish colour. They are not always fully saturated however and they do not 

contain calcium carbonate. 

Mull Soils 

This class is represented by the group of Eutrophic Brown Soils (E), the central concept of 

which was discussed by Maignien (1963). 

The structure of these rather fine-textured soils is clearly expressed, being usually 

granular in the surface horizons and weakly subangular blocky below. The organic carbon 

content is high (about 2-3 per cent). The red hues and strong colours are caused by the 

liberation of free iron oxides. The clay minerals are mostly 2:1 lattice types and the soil 

has abundant reserves of weatherable minerals. The soil reaction is neutral and the cation 

exchange capacity is 15-25 meq per cent soil. They are rich in bases, particularly calcium 

and magnesium, and base saturation is usually more than 50 per cent. 

The Eutrophic Brown Soils are developed only on basic parent material. This mostly consists 

of basaltic rocks, although there are some outcrops of gabbro and epidiorite within the 

Basement Complex. The physical nature of the rock appears to be an equally important factor 

in the formation of-these soils as they are generally not found over solid lava. The 

average annual rainfall of the order of 1 000 mm (39 in), concentrated into a 5-month rainy 

season, is apparently not high enough to alter and leach solid basic rock. 

The Eutrophic Brown Soils occur mainly on better-drained sites. Some contain iron concretions 

and represent a transition to Ferruginous Tropical Soils, while on lower slopes, under 

conditions of impeded drainage, vertic properties are developed and the Eutrophic Brown Soils 

are replaced by the vertic group of Hydromorphic Soils or by Vertisols. 

The most extensive areas of Eutrophic Brown Soils are found on the Biu Plateau where they 

are associated with, shallow and stony soils on volcanic cones and on rocky scarps. 

Ferruginous Tropical Soils 

The Ferruginous Tropical Soils are a sub-class of the Sesquioxide Soils. They are chiefly 

characterised by the accumulation of free iron oxides within their profile, particularly in 

the deeper horizons; they often have strong yellowish or reddish brown colours and regularly 

contain iron concretions. The organic matter content is very low and humus is rapidly 

decomposed (Dabin, 1967). These soils contain illitic as well as kaolinitic clay minerals; 

their cation exchange exchange capacity of 20-40 meq per cent clay is relatively high. Base 

saturation is also moderately high to high, usually being greater than 40 per cent. There 

are appreciable reserves of weatherable minerals in some of these soils. 

Segalen (1967) has recently reviewed the factors affecting the formation of these rather 

varied soils. It appears that a total annual rainfall of over 500 mm (20 in) is necessary 

before a soil will develop the properties of a Ferruginous Tropical Soil. The pronounced 

seasonal changes of climate, when a wet, reducing pedo-climate is followed by dry, oxidising 

conditions, strongly influences the redistribution of sesquioxides in the profile. 

Generally soils in the south of the country are more strongly leached and consequently more 

acid and base-unsaturated than those on similar parent materials in the north. 

The first signs of leaching in the profile are the appearance of thin bands of lamellae, of 

iron and clay accumulation. Eventually the soil may show a clear textural B horizon and 

evidence of clay translocation such as clay skins. 

In many soils, particularly under poorer drainage conditions, iron deposition takes the form 

of mottles or concretions. If deposition continues for long periods an ironpan may be 

formed. Also, under poor drainage conditions, accumulation of calcium carbonate is often 

observed. 

91

Two major groups of Ferruginous Tropical Soils are recognised: Non-Leached and Leached 

Ferruginous Tropical Soils. 

1. Non-Leached Ferruginous Tropical Soils (Fn) The clay content of these soils is 

approximately constant throughout the profile, but there may be translocation and accumulation 

of iron and development of soil structure. 

Two families of this group can be distinguished. Non-leached soils are common on the aeolian 

drift which overlies the Chad Sediments in many places. The material is very sandy and 

therefore a textural B horizon would not easily develop. Lamellae are common features of 

these dune soils. The other family of non-leached soils is found in colluvial material, 

which surrounds hilly areas on both Basement Complex and sandstone formations. These soils 

are also very coarse, but some iron concretions are regularly observed. 

2. Leached Ferruginous Tropical Soils This very important group is further divided 

into 4 sub-groups, all of which have a textural B horizon. 

a. Without or with few concretions (Fl) In these soils the translocation of iron is 

only apparent in the form of a colour B horizon or as mottles. The mottles may harden into 

concretions which are never frequent. The soils without concretions gradually merge with 

the Non-Leached Ferruginous Tropical Soils on the one side and with the concretionary and 

hydromorphic ones on the other. They normally occur on gentle slopes over sands, sandstones 

and granite. 

b. With concretions (Fc) Here the iron accumulation is very strong and an almost continuous 

layer of iron concretions is found at a depth varying from 45-130 cm (18-50 in). 

This layer sometimes hardens to form an ironpan. This sub-group is restricted to erosion 

surfaces, where soil formation has continued uninterrupted for long periods. Locally, at 

breaks of slope, calcium carbonate concretions are found associated with the iron 

concretions. 

C. Hydromorphic (Fy) These soils shows some properties which may be attributed to 

hydromorphic conditions. They often have a clear distinction between the textural B horizon 

and the overlying leached layer, which may be bleached. The colours are always pale or grey 

and the soils are mottled at a relatively shallow depth. They often contain calcium 

carbonate concretions and are highly saturated. They gradually merge into leached 

Halomorphic Soils, from which they are distinguished by the lower sodium content. Olivecoloured 

soils, with or without calcium carbonate concretions, formed from mudstones, can be 

regarded as transitional between Vertisols and Hydromorphic Ferruginous Tropical Soils. The 

Hydromorphic Ferruginous Tropical Soils mainly occur in flat areas with very slow external 

drainage. 

d. On poor material (Fp) These soils occur only on material derived from the Kerri 

Kerri Sandstone. This material has passed through several cycles of weathering and the 

cation exchange capacities of 17-22 meq per cent clay are low for Ferruginous Tropical Soils. 

The great depth and red colour of these soils suggests that they are only marginal members 

of this sub-class. A textural B horizon exists, but at greater depth (2-3 m) (7-10 ft) than 

is considered normal. 

These soils cannot be satisfactorily classified in the French system. In the past Nigerian 

workers have classified them as Ferrallitic Soils (Tomlinson, 1967) and Ferrisols 

(Klinkenberg and Higgins, 1968). It is now felt that they have more the properties of the 

Ferruginous Tropical Soils but, to indicate their special characteristics, the subdivision 

of Ferruginous Tropical Soils on poor material is proposed. 

Two families can be distinguished: one over ironpan or iron concretions near Potiskum and a 

non-concretionary family in the Wawa Bush (Land Systems Illbl and 2). 


Halomorphic Soils are those whose characteristics are mainly determined by the presence in 

the profile of soluble salts and high levels of exchangeable sodium. They have not been 

studied in great detail in North East Nigeria, but 3 groups are known to exist: Saline Soils, 

Non-Leached Alkali Soils and Leached Alkali Soils. 

1. Saline Soils Saline Soils have a conductivity (in 1:5 water suspension) which is more 

than 7 millimhos per cm at 25°C. They appear to be confined to the extreme north of the 

country, although slightly saline soils occur elsewhere as subdivisions of other soil 

classes. These soils commonly have salty crusts or efflorescences, particularly of sodium 

sulphate. 

92

2. Non-Leached Alkali Soils The clay complex of these soils is dominated by alkaline 

cations, which disperse the clay fraction, giving rise to very compact profiles. The most 

effective cation is sodium, but it has been claimed that magnesium may behave similarly 

(Ehrlich and Smith, 1958). The clay content of the non-leached soils is approximately constant 

throughout the profile. They are mostly fine-textured, often with some hydromorphic 

or vertic properties. Transitions to the Vertisols are indicated on the map (Hv). Many 

soils also contain calcium carbonate concretions and transitions to the Semi-arid Brown 

Soils also exist (Ha). 

3. Leached Alkali Soils This widespread soil group has the very characteristic 

morphology of the Solodised Solonetz. Similar soils have been described from other parts of 

the Chad Basin (Bocquier, 1964) and from many other tropical and temperate countries. 

The profile consists of a thin, pale coloured, slightly acid, loamy sand surface horizon, 

which is very porous; there is a sharp boundary to a stronger-coloured, compact, strongly 

alkaline sandy clay, with well expressed columnar structure. At the base of this B horizon, 

carbonate concretions and pseudomycelia are commonly found and there is a gradual transition 

to the parent material. The exchangeable sodium content of these soils can vary widely and 

Coulter (1967) has noted that it bears little relation to their morphological development. 

It would appear that the commonly accepted limit of 15 per cent of the exchange complex being 

saturated with sodium is too high. Nigerian examples of this soil vary in the clarity of 

expression of the columnar structures and the analyses available tend to support Janzen and 

Moss (1956) in saying that the round-topped columns only develop when the exchangeable sodium 

percentage is greater than 10. 

The Alkali Soils are found only on medium-textured deposits in the drier northeastern part 

of the area, often with a bare 'sheetwashed' appearance to the ground. The probable source 

of the sodium is the acid igneous rocks of the Basement Complex. 

The Alkali Soils usually occur in association with non-alkaline Hydromorphic Soils and with 

Weakly Developed Soils. 


The characteristic properties of the Hydromorphic Soils are caused by seasonal or permanent 

waterlogging. They are very variable and have been divided into 2 sub-classes: Organic and 

Mineral Hydromorphic Soils. 

1. Organic Hydromorphic Soils (Yo) The upper horizon of these soils contains at 

least 20 per cent organic matter. They are restricted to the edge of Lake Chad, where the 

swamp vegetation provides the organic matter. The soils are often somewhat saline. 

2. Mineral Hydromorphic Soils (Y) Soils of this sub-class have gley horizons, in 

which reduction is the dominant process, or pseudogley horizons, where mottles and concretions 

of reoxidised compounds occur. These gley or pseudogley horizons are found either near 

the surface or at depth. Some soils contain carbonate concretions. Soils with well 

developed properties, such as textural B horizons, typical for other classes, are excluded 

from the Hydromorphic Soils. 

Hydromorphic Soils generally form over relatively impermeable fine-grained parent materials, 

even on sites with fairly good external drainage. Such parent materials include the more 

argillaceous Chad sediments and colluvial products of basaltic origin. They also develop in 

poorly drained low-lying sites and they cover all but the coarsest-textured alluvial and 

deltaic deposits. 

In alluvial areas the Hydromorphic Soils are usually associated with Halomorphic Soils and 

with Weakly Developed Soils. Many alluvial areas are too small to be shown on the soil map. 

Transitions from Hydromorphic Soils exist: 

to the Weakly Developed Soils, in more freely draining conditions; 

to the Hydromorphic sub-group of the Ferruginous Tropical Soils, when a textural B 

horizon is developed; 

to the Halomorphic Soils with increasing salinity and sodium content; 

to the Vertisols with increasing clay content and surface cracking. 

The transitions to the Vertisols are important enough to be shown separately on Map 3 (Yv). 

This transitional group has wide surface cracks, like the Vertisols, but the cation exchange 

93

capacity is below 30 meq. These soils also are normally mottled to the surface and they 

often contain some iron concretions. They are common on the colluvial basaltic material to 

the northeast of the Biu Plateau and also in the Ngaje Plains in the far northeast. 

The main characteristics and relationships of the soils described are summarised in Tables 5 

and 6. 

SOIL PATTERNS* 

Introduction 

Most of the 40 units of the soil map are combinations of 2 or more categories of the classification. 

Normally only the 2 most important categories are indicated in the map symbol. 

In some cases the constituent categories are closely related, for instance when nonconcretionary 

soils occur on upper slopes and soils with ironpan occur on lower slopes in 

the same area. In other cases 2 quite different soils may occur in close conjunction. This 

is due either to the presence of 2 or more different parent materials, or because recent 

erosion is breaking up an old landscape. In cases where contrasting categories occur 

together they are separated by a stroke in the map symbol, for example Pn/Vt. 

Basement Complex 

The soil patterns in the Basement Complex area are closely related to differences in landform. 

6 main types of landform can be distinguished: Hills; Pediments; Undulating areas; 

Plains; Dissected areas; Alluvial valleys. There are not always clear-cut distinctions 

between the main types and gradual transitions occur frequently. The main different types 

of landform and their associated soil patterns are illustrated in Figure 8. 

The hill complexes (Land Systems Icl to Ic5) and also the Hawal Escarpment (Land System Ic6) 

are dominated by rock outcrops, rubble accumulations and very shallow, stony soils. These 

are mapped (Map 3) as Raw Mineral Soils and Weakly Developed Soils of erosion (RWe). 

Locally deep pockets of sandy colluvial or alluvial material occur. In the larger valleys 

(Land Systems Id2 and Id8) and also on the pediments (Land Systems Idl and Idll) surrounding 

the hills, these colluvial and alluvial accumulations are often large anough to be shown on 

the map. The soils have little or no profile development and are mapped as Weakly Developed 

Soils of deposition and Non- or Weakly Leached Ferruginous Tropical Soils (WdFn). They are 

generally deep to very deep, well drained, coarse-textured (less than 20 per cent clay) 

soils and they normally contain unweathered quartz, feldspar and mica. The Weakly Developed 

Soils often retain their original stratification, while in the Non- or Weakly Leached 

Ferruginous Tropical Soils (example, Kaltungo Series) some iron concretions may occur. The 

degree of soil profile development on the pediments increases with distance from the hills: 

the Weakly Developed Soils are found close to the hills, the Non- or Weakly Leached 

Ferruginous Tropical Soils further away. 

On very large pediments, such as those occurring to the west of the Mandara Mountains (Land 

System Id6), and on gently undulating areas (Land System Ia2) the soils have horizons of 

accumulation of clay and iron oxides and a considerable proportion of them can be classified 

as Leached Ferruginous Tropical Soils. Near rock outcrops Non- or Weakly Leached 

Ferruginous Tropical Soils (example, Kaltungo Series) and shallow soils (example, Busra 

Series) are common. On Map 3 this combination is indicated with the symbol FnFl. The most 

common soils are well drained, brown sandy loams (example, Barriki Series) which often contain 

unweathered fragments of feldspar and mica lower in the profile. Locally, in areas of 

poor drainage, grey, mottled sandy clays or sandy clay loams are found. These sometimes 

contain calcium carbonate concretions and may have a prismatic structure (example, Burashika 

Series). They are classified as the Hydromorphic sub-group of the Leached Ferruginous 

Tropical Soils, but are generally not of sufficient extent to merit separating on the soil 

map. Only on the Butuku Plain (Land System Ib7) do these soils become dominant, where they 

occur together with Vertisols, to which they are related (VIFy on Map 3). 

On old land surfaces, such as occur to the west and northwest of Mubi, soil formation has 

continued for a long time and the soils contain many iron concretions which are often 

cemented together to form ironpan. These soils are classified as Leached Ferruginous 

Tropical Soils with concretions (example, Gombi Series) and shown on Map 3 with symbol Fc in 

Land Systems Ibl and Ib2. They occur together with non-concretionary soils in Land System 

Ib3 and these are shown as FIFc. These old land surfaces are attacked by erosion in varying 

•For each example, profile descriptions and analyses are presented as an appendix in Volume 5. 

94

Basement 

Complex 

Steep R 

We 

Accumulating Wd 

Upper slope 

Middle slope 

Fn 

Cretaceous 

Sandstones 

R 

We 

Fn 

Fl 

TABLE 5 Relations between soil, parent material and site 

Basalt 

R 

We 

Fn Fn E 

Fl 

Lower slope 

" 

Fl 

alns Yv wm Old surfaces Fl 

Fe 

Note: For an explanation of the symbols used, see Map 3. 

Fl 

E 

Transitional 

formations 

Fl ^ ^ "'VI VI Vt / 

Fl 

Fe 

Alluvium 

Lacustrine 

deposits High Low 

rainfall 

Clayey 

Chad 

Fl ^ ^ ? Wd Wd Wd Fl Fn 

""\^H1 

Vt /Tv Yv /Hv 

~t»-^ 

Sandy 

Chad 

Wa 

Fn 

Y Y / HI A 

Pn " 1 Pn " 1 

Kerri Kerri 

Sandstone 

R 

We 

Fp 

Pp 

Fp 

Fp/c

Category 

(Map 3) 

Wd 

E 

Fn 

PI 

Fp 

Pc 

Fy 

VI 

Vt 

Yv 

Hv 

H 

Clay 

content 

% 

Low 

25-40 

20 

20-35 

15-25 

30-50 

30-50 

35-75 

50-80 

35-70 

+30 

10-30 

B horizon 

Stratified 

Structural 

Lamellae 

Colour ) 

Textural) 

Moderate 

Ironpan 

Textural 

No 

No 

No 

No 

Textural 

TABLE 6 Main characteristics of soil categories 

per 

100 g 

soil 

15-30 

30-50 

30-40 

15-30 

15-30 

CEC: Cation exchange capacity in meq % soil/clay 

Sat: Base saturation % 

ESP: Exchangeable sodium % 

CEC 

per 

100 g 

clay 

in B horizon (subsoil) 

30-80 

20-70 

17-22 

30-40 

20-70 

50-100 

40-50 

35-45 

40-100 

Sat ESP PH 

40-100 

30-100 

40-75 

40-60 

60-90 

60-100 

50-100 

80-100 

80-100 

100 

100 

0-1 

0-2 

0-1 

0-1 

0-10 

0-10 

5-10 

0-10 

10 

10 

6.5-7.5 

6.0-7.0 

5.5-7.5 

4.5-7.0 

6.0-7.0 

6.0-9.0 

6.0-9.0 

7.0-8.5 

6.5-9.0 

6.0-10.0 

6.0-10.0 

Organic 

carbon 

in 

topsoil 

% 

Low 

2.0 

0.7-0.0 

0.3-1.7 

0-0.4 

0.5-1.5 

0.5-1.5 

0.3-2.0 

0.3-2.0 

0.3-1.5 

0.1-0.4 

0.1-0.4 

Structure 

Nil to very weak 

Crumb at surface 

Very weak 

Moderate 

Weak to moderate 

Moderate 

Moderate to strong blocky 

Strong prismatic 




Strong columnar

Mapping Units Wd Fn 

Fn 

(Kaltungo Series) 

Soil patterns on Basement Complex 

a Hills and pediments 

Mapping Units Rwe FnFI 

Mapping Units 

Fc (Gombi) 

+ + 

b (Gently) undulating areas 

Fl 

(Barriki) 

We Wd 

(Burashika) 

Figure 8 

•••*•*•.*•*•••••* * V » V * * * V * - * * Y * . V * • • • % • * • • • * * 

c Old surfaces 

Mapping Units Fc/We We Fn Fc/We 

DOS. 3099 H 

d Dissected areas 

97

degrees. In the Doksa Plain (Land System Ib4) the number of valleys with eroded soils is 

sufficient to be mentioned on Map 3 (symbol Pc/We). The soil patterns of the Tum and Zomba 

Plains (Land Systems Ib5 and Ib6) resemble those of the hill complexes previously described; 

erosion has almost completely destroyed the old surface and only shallow soils remain, 

although in the valleys there are colluvial accumulations of sandy material, with weak profile 

development (WeFn on Map 3). 

Some of the properties of the main soil classes found over the Basement Complex are summarised 

in Table 7. 

Cretaceous Sandstones 

This section describes the soil patterns developed over the Bima and Gombe Sandstones and 

also those over the southwestern part of the Chad Formation in the area south of Gujba. The 

sandstone members of the transitional formations are discussed below.. 

The soil and landscape pattern over the sandstones are very similar to those on the Basement 

Complex. They are illustrated in Figure 9. 

The hill complexes (Land Systems IIcl, 2 and 3) once again are dominated by rock outcrops, 

rubble accumulations and very shallow, stony soils. They are mapped as Raw Mineral Soils 

and Weakly Developed Soils of erosion (RWe). In the Gombe Hills (Land System IIc3) and the 

Korode Escarpment (Land System IIc2) ferruginised sandstone and ironstone are common on the 

upper slopes. In the Balbaya Plains (Land System IIb4) and the Kuma Plain (Land System 

IIb8) there is a linear pattern of alternating rock outcrops and shallow Ferruginous 

Tropical Soils (R/Fl). 

Extensive pediment slopes are found only about the Filiya-Lamurde hill range and in the 

Gombe Sandstone areas (Land Systems IIb2 and IIb7). Around Gombe much of the colluvial 

material is derived from nearby occurrences of the Kerri Kerri Sandstone. The soils of 

these pediments are deep to very deep sands, with little to moderate profile development 

(example, Malori Series); they are mapped as Non- or Weakly Leached and Leached Ferruginous 

Tropical Soils (FnFl). They are sometimes underlain by shales of the transitional formations 

and they normally remain moist for a considerable time into the dry season. 

In gently undulating areas (Land Systems Ilbl, Ilbll and Val) the soils are mainly sedentary 

and the profiles are well developed. Rock outcrops and shallow soils may be found on the 

upper slopes. The deeper soils are mainly sandy clay loams, changing in colour from reddish 

brown on the upper slopes (example, Busari Series) to light yellowish brown and grey with 

mottles on middle and lower slopes (example, Ninowa Series). In flat areas with poor 

external drainage finer-textured soils containing calcium carbonate concretions are found. 

These are classified as the Hydromorphic sub-group of the Leached Ferruginous Tropical 

Soils, but most of the soils in these areas belong to the normal sub-class without concretions 

and are mapped as such (Fl). The soil distribution pattern is very similar to that 

over the Basement Complex, but grey soils are more common on the sandstone and the cation 

exchange capacity of the sandstone soils is slightly lower. 

On older land surfaces mainly occurring in the eastern part of the area the soils are more 

strongly developed and contain iron concretions or even ironpan. They are classified as the 

concretionary sub-group of the Leached Ferruginous Tropical Soils; they are dominant in Land 

System IlblO (Map 3 symbol Fc) and occur together with non-concretionary soils in Land 

System IIb9 (symbol FIFc). In the Gumsuri Plain (Land System IIb3) several valleys with 

very shallow soils have been eroded into the plain and this area is mapped as Fc/We. 

Alluvial soils occur throughout the sandstone areas, but are mapped only where they are very 

extensive. 

Some of the properties of the main soils over the sandstones are summarised in Table 8. 

Transitional Formations 

The transitional formations include the complex of marine and continental sediments laid 

down between the Bima and the Gombe Sandstones. They occur mainly in the Gongola Valley and 

on either side of the Filiya-Lamurde anticline. Lithologically they consist of shales, mudstones, 

sandstones and limestones, often in rapidly alternating succession. Because of 

these rapid variations in parent rock the soil patterns are often very complex. 

Each of the rock types produces a distinctive soil. The shales normally give rise to 

Vertisols (example, Mutwe Series); olive-brown to grey-brown clay soils, which crack 

severely during the dry season, and which have a cation exchange capacity of more than 

98

Soil 

unit 

(Map 3) 

Clay in 

B horizon 

% 

Development 

of texture in 

B horizon 

Wd 5-20 Often 

stratified 

TABLE 7 Properties of soils on the Basement Complex 

Colour 

Fn 5-20 Very weak Yellowish 

brown 

PI 20-35 Very good Reddish 

brown to 

grey 

Fc 30-50 Very good Reddish 

brown 

Depth to 

Concretions CEC Sat ESP PH 

mottling 

iron carbonate in B horizon topsoil subsoil 

Pale Variable None None 

Organic 

carbon in 

topsoil 

% 

10 cm Pew None 50-80 70-100 0-2 6.0-7.0 6.0-7.0 0-0.7 

75 cm Few None 30-70 40-75 0-1 5.5-7.5 5.5-7.5 0.4-1.7 

50-100 

cm 

Py 30-50 Moderate Grey 15-50 

cm 

CEC: Cation exchange capacity in meq % clay 



Many Locally 30-40 60-90 0-1 6.0-7.0 6.5-7.5 0.5-1.5 

Few Commonmany 

30-70 60-100 2-10 6.0-7.0 6.0-9.0 0.5-1.5

Mapping Units 

Mapping Units 

Mapping Units 

D.O S 3099 ] 

Fc 

(Gumsuri) 

Soil patterns on Cretaceous Sandstones Figure 9 

a Hills and pediments 

b Gently undulating areas 

c Old surfaces with incised valleys 

100 

Fl 

(Ninowa)

Soil 

unit 

(Map 3) 

Wd 

Fn 

PI 

Fy 

Pp 

Clay in 

B horizon 

% 

0-20 

5-20 

20-40 

30-45 

20-45 

Development 

of texture in 

B horizon 

Nil 

Nil or 

very weak 

Good 

Good 

Very deep 

TABLE 8 Properties of soils on sandstone (including Kerri Kerri) 

Colour 

Pale 

Red to 

reddish 

brown 

Brown to 

grey 

Grey 

Red 




Depth to 

mottling 

Variable 

150 cm 

15 cm 

15 cm 

No 

No 

Concretions CEC Sat ESP PH 

iron carbonate in B horizon topsoil subsoil 

Pew 

Pew 

to 

common 

Common 

No 

No 

No 

No 

Common 

No 

30-45 

20-40 

20-45 

17-22 

40-60 

40-100 

80-100 

40-60 

0-7 

0-1 

1-10 

0 

5.8-7.0 

6.0-7.5 

5.8-7.0 

5.8-7.0 

4.8-6.0 

5.4-7.0 

7.0-9.0 

4.5-6.0 

Organic 

carbon in 

topsoil 

% 

0-0.5 

0.3-1.5 

0.5-1.5 

0-0.4

30 meq per cent soil. Where limestone bands are present in the shale, calcium carbonate concretions 

are commonly found in the soil. Sometimes gypsum crystals are present, in which case the 

electrical conductivity is high. 

An olive-brown sandy clay develops from mudstones and very fine sandstones. The cation 

exchange capacity is less than 30 meq per cent soil and only small cracks develop during the dry 

season. These soils have a strongly developed angular blocky structure as opposed to the 

prismatic structure of the Vertisols. They often contain calcium carbonate concretions. The 

textural B horizon is moderately to fairly well developed and ferro-manganese concretions are 

commonly found. These soils are classified in the Hydromorphic sub-class of the Leached 

Ferruginous Tropical Soils (example, Nono Series). 

Leached Ferruginous Tropical Soils, without concretions, similar to those described in the 

section on the soils over Cretaceous sandstones, are found over coarser-textured sandstones 

within the transitional formations. There are also occasional outcrops of sandstone rock. 

Complications occur when 2 different parent materials are found within 1 profile. This 

happens when material derived from l rock is washed down the slope and then overlies other 

material or when different strata alternate at very rapid intervals. Sometimes a Vertisol is 

found over sandstone, sometimes a coarse-textured profile over shale. A mottled sandy clay 

loam commonly overlies a strongly structured clay with calcium carbonate concretions (example, 

Zangaya Series). This soil is also classified in the Hydromorphic sub-class of the Leached 

Ferruginous Tropical Soils. 

The complexity of the soil patterns depends largely on the angle between the surface and the 

dip of the geological strata. Where this angle is very small the soils are normally rather 

uniform, but where it is large the variation in soils can be very rapid. Some examples of 

this are shown in Figure 10. The properties of the main soils are summarised in Table 9. 

In Map 3,4 different symbols are used for the soils over the transitional formations, 

depending on the relative abundance of the component soils. In the Wagur Plains (Land 

System IId4) the Vertisols are dominant and the area is therefore mapped as VIFy, while 

further south in the Numan and Dadiya Plains (Land Systems Ildl and IId2) and also in the 

Dusu Plains (Land System IId5) the Vertisols are not so extensive and the Hydromorphic subclass 

of the Ferruginous Tropical Soils becomes the more important and the unit is given the 

symbol FyVl. In the Bajoga Plains (Land Systems IIb5), where shales are of very minor 

extent, there are only few Vertisol occurrences; the main soils belong to the Hydromorphic 

and non-concretionary sub-groups of the Leached Ferruginous Tropical Soils (FIFy). The 

Bajiram Plain (Land System IId3) is covered by a clay deposit which is probably derived from 

the Longuda Basalt to the west; Vertisols are developed on this clay and other soils are 

almost completely absent (VI). 

Kerri Kerri Sandstone 

The Paleocene Kerri Kerri Sandstone is in some places, particularly in the north, strongly 

ferruginised or capped by ironpan. Over most areas however the rock is covered by a thick 

mantle of loose material and only rarely outcrops. The mode of deposition of the surface 

layers is unknown, but a dune pattern, only visible on the aerial photographs, suggests an 

aeolian reworking of the material. 

The material has undergone several cycles of weathering and this, in conjunction with its 

great thickness, is of great importance in determining the character of the soils. Only in 

the north, around Potiskum, is the ironpan extensive and the cover of reworked material 

rather thin. Even there, some of the soil properties are caused by the material undergoing 

several cycles of weathering. 

The soils over the Kerri Kerri Sandstone are generally of very great depth, red in colour, 

and have a cation exchange capacity of 17-25 meq per cent clay (eg Wawa Series). These 

properties are characteristic of the Ferrallitic Soils, which are normally found under much 

wetter climates, but other properties, such as moderate base saturation and the presence of 

a textural B horizon, are typical of Leached Ferruginous Tropical Soils. It would appear 

that the soils have developed during wetter periods in the past, but are now exposed to 

pedogenetic processes that would result in Ferruginous Tropical Soils. After discussions 

with French pedologists it has been decided to classify and map these soils as Ferruginous 

Tropical Soils on poor material (Fp on Map 3). 

The textural B horizon is at great depth and can only be discerned in very deep profiles. 

The increase of clay with depth is shown in Figure 11. There is very little or no variation 

in soils at different positions along the slope, because the watertable in this permeable 

material is at very great depth and all soils are freely to excessively drained. 

102

Mudstone 

Soil patterns on transitional formations 

Mapping Units VIFy 1 -| 

- Fy Fl - VIFy 

Sandy soil Non-cracking clay Cracking clay 

rrr 

Shal ' c J\ Mudstone 'i- 

Sandstone f 

Limestone ,./ Sandstone 

Shale 

Mapping Unit 

Sandstone ' 

Mapping Units 

RWe 

Longuda Plateau 

D.O.S. 3099 K 

Non-cracking clay 

Sandstone' 

b Complex pattern 

a Moderately homogeneous patterns 

Mixed soil 

between Longuda Plateau 

VIFy 

Mudstone 

VI 

Banjiram plain 

Cracking clay 

Sandstone' 

103 

Figure 10 

Sand over clay

Soil 

unit 

(see 

footnote) 

1 

2 

3 

4 

Clay in 

B horizon 

% 

20-40 

25-60 

25-45 

.35-75 

Development 

of texture 

in 

B horizon 

Good 

* 

Moderate 

No 

TABLE 9 Properties of soils on transitional formations 

Concretions CEC 

Sat ESP 

Colour Mottling Structure 

soil clay 

iron carbonate 

in B horizon 

Brown to 

grey 

Grey over 

olive 

brown 

Olive 

brown 

Grey 

brown 

Common 

Many 

None 

Pew 

Moderate 

blocky 

Strong 

blocky 

Strong 

blocky 

Strong 

prismatic 

Few to 

common 

Pew to 

common 

Pew to 

common 

Very 

few 

No 

Variable 

Variable 

Variable 

5-15 

15-30 

20-30 

30-50 

20-40 

40-60 

40-70 

50-100 

40-100 

70-100 

80-100 

50-100 

0-1 

3-10 

4-7 

0-10 

PH Organic 

carbon 

in 

topsoil subsoil topsoil 

% 

6.0-7.5 

5.0-7.5 

6.0-7.0 

6.0-8.0 

6.0-7.0 

6.0-9.0 

8.0-9.0 

6.3-9.0 

0.3-1.5 

0.5-1.3 

0.5-1.3 

0.3-2.0 

1 Soil over sandstone (PI) CEC: Cation exchange capacity in meq % soil/clay 

2 Sandy soil over clay (Py) Sat: Base saturation % 

3 Clay soil over mudstone (Fy) ESP: Exchangeable sodium % 

4 Clay soil over shale (Vt) 

*Two parent materials in 1 profile

D.O.S. 3099 L 

Clay content of three soils on Kerri-Kerri Sandstone Figure 11 

50 

100 

ISO 

200 

250 

300 

350 \- 

400 \- 

450 

500 

10 15 20 25% clay 

1 1 1 1 

105

This kind of soil is dominant throughout the southern part of the Kerri Kerri Sandstone area, 

and covers most of Land Systems Illbl and IIIb2. Locally (as in Land System IIIb3) areas of 

ferruginised sandstone emerge through the loose material. These are normally hilly features 

with rock outcrops and shallow soils, shown on Map 3 as Raw Mineral Soils and Weakly 

Developed Soils of erosion (RWe). In some of the deeper valleys (Land System Illdl) either a 

perched or permanent watertable is close to the surface and Hydromorphic Soils and Weakly 

Developed Soils are found (Y/Wd). 

In the north, around Potiskum, the cover of loose material is very much thinner and the soils 

mostly overlie ferruginised sandstone or ironpan at shallow depth. They are still classified 

as Ferruginous Tropical Soils on poor material, but the underlying ironpan is indicated by 

the suffix 'c' in the map symbol: Fpc. This mapping unit also includes soils on similar 

sites in the Chad Formation (Land System Vc3). Areas where rocky soils predominate have also 

been separated (RWe). 

The Kerri Kerri Sandstone is strongly dissected between Potiskum and Fika (Land System IIIcl) 

and near Yuli (Land System IIIc2). These areas are characterised by very steep rocky slopes 

and valleys with very deep sandy soils. The valley soils have little or no profile development 

and these areas are therefore mapped as Raw Mineral Soils and Weakly Developed Soils of 

deposition (R/Wd). 

Basalt 

The volcanic Biu Upland (Land System IVal) and the Longuda Upland (Land System IVa2) have 

many shallow and stony soils; the basic rocks do not appear to weather deeply under the prer 

vailing climatic conditions. The nature of the underlying rock greatly influences the 

resulting soil; where the parent material is a solid, blocky lava with weak jointing, a 

poorly drained firm clay with vertic tendencies results and where it is a tuff or agglomerate 

a better-drained friable loam, tending towards a Eutrophlc Brown Soil, is found. 

The various lava flows are separated by numerous small scarps where rock outcrops and shallow 

soils predominate. The same applies to the high, steep scarps, which surround the Plateaux 

in places. The volcanic cones of the Biu Hills (Land System IVcl) also have stony, shallow 

soils. These cones are surrounded by an area of deep, relatively stone-free red friable 

clays. These soils are freely draining, although they occur on very gentle slopes; they 

appear to be formed from reworked ash or tuff deposits. The cones on the Garkida Plain 

(Land System IVdl) and the Song Volcanic Complex (Land System IVd2) are associated with rocky 

rubble and shallow stony soils over lava. 

Reddish brown or yellowish red loams and clays are also found on slightly elevated sites on 

the Biu and Longuda Plateaux. These Eutrophic Brown Soils are most common in areas of 

pyroclastic rocks and are also found on the flattish tops of lava flows, wherever weathering 

is strong enough to produce a deep soil (example, Pulda Series). In some localities the 

underlying rock is slightly ferruginised and the soils possess a weakly cemented concretionary 

horizon, thus forming a transition towards the Ferruginous Tropical Soils. 

Much of the Biu Upland consists of a series of basins where clayey colluvium covers the lava 

flows. The chaotic organisation of these deposits and the fact that they can be traced from 

volcanic craters suggests that they are formed, in part at least, by volcanic mudflows. 

There is a clear toposequence of soils in these gently sloping basins. The upper and middle 

positions are covered by brown, firm, imperfectly drained clays (example, Kuda Series); deep 

cracking, slickensides and other vertic properties are more strongly developed in the poorly 

drained clays of the lower slopes and very poorly drained soils with abundant calcium carbonate 

concretions occur in the bottom lands (example, Pawa Series). 

The Biu Plains (Land System IVbl) have poor surface drainage and give rise to grey cracking 

clays with many calcium carbonate concretions. The clays are frequently very compact and 

they may have appreciable sodium contents. They are classified and mapped (Map 3) in the 

vertic sub-group of the Hydromorphic Soils (Yv) (example, Gur Series). The soils are often 

stony and the surface may be covered with basalt rubble. In some areas large heaps of 

boulders cover the plains, forming shallow, stony soils. 

Some of the properties of the soils derived from basalt are summarised in Table 10, while the 

topographic relations are illustrated in Figure 12. 

As stated above, the soil patterns of the Biu and Longuda Uplands and the Biu Hills are very 

complex. Rock outcrops, Weakly Developed Soils of erosion, Vertisols and Eutrophic Brown 

Soils occur frequently. However, the frequency of the various groups varies from place to 

place. On Map 3 the dominant soil group is indicated. Rock outcrops and shallow soils are 

106

Soil 

unit 

(Map 3) 

Clay in 

B horizon 

% 

Development 

of texture 

B horizon 

Colour 

We 0-20 No Brown to 

grey 

E 30-50 No or weak Brown to 

red 

VI 40-55 No Brown to 

grey 

Yv 45-60 No Olive to 

grey 

CEC: Cation exchange capacity in meq % soil/clay 



TABLE 10 Properties of soils on basalt 

Depth to 

mottling Structure 

Depth to 

mottling 

Structure 


soil clay 

Sat ESP 

Structure 

Depth to 

mottling 


soil clay 

Sat ESP 

Structure 


in B horizon 

- Weak, 

variable 

- 

Crumb to 

subangular 

blocky 

20-50 cm Subangular 

blocky to 

prismatic 

10-30 cm Subangular 

blocky to 

prismatic 

PH Organic 

carbon 

in 

topsoil subsoil topsoil 

% 

Few Few - - - - - - - 

Pew to 

common 

Common Few to 

common 

Few to 

common 

None 10-15 20-30 60-80 0-1 6.5-7.0 6.5-8.0 1-3 

20-40 40-80 80-100 0-5 6.5-7.5 7.5-8.5 0.7-1.5 

Many 20-35 40-70 80-100 1-5 7.0-8.0 8.0-9.0 0.4-1.0

Mapping Units 

Mapping Units EWe 

Mapping Units EWe 

O.O S 3099 M 

Pulda Series 

Kuda Series \ 

Soil patterns on basalt 

Tuff 

a Biu Hills and surroundings 

b Biu Upland 

RWe 

c Biu Upland and Biu Plain 

108 

Yv 

Gur Series 

Figure 12

dominant on the steep scarps: RWe. The flatter areas on the Plateaux are dominated either by 

Eutrophic Brown Soils or by Vertisols; but shallow soils remain frequent and the map symbols 

are VlWe and EWe. 

The Garkida Plain and the Song Volcanic Complex are also mapped as RWe. 

Chad Sands and Clays (sensu stricto) 

In the chapter on geology the Quaternary Chad Formation was divided into 7 units. The soil 

patterns associated with these units are however more conveniently discussed as 4 groups: 

sands and clays ("sensu stricto); 

sands, including wind-blown material and beach ridges; 

lagoonal clays; 

alluvial deposits. 

The group of mixed sandy and clayey deposits is only of importance to the southwest of 

Maiduguri. In the west of that area the topography is gently undulating (Land System Val) 

and the soil pattern is very similar to that found over the Bima Sandstone. Most of the 

soils can be classified as Leached Ferruginous Tropical Soils without concretions (Fl on 

Map 3). 

The eastern section (Land System Va2) is almost flat and the drainage is impeded. The soils 

are dominantly grey, mottled sandy clay loams with a well developed structural B horizon, 

(example, Kirik Series). In local depressions and drainage lines the contrast between 

structure in upper and lower horizons is even greater; it is caused by an accumulation of 

sodium (example, Latan Series). These soils are mapped as the Hydromorphic sub-class of the 

Leached Ferruginous Tropical Soils and Leached Halomorphic Soils (FyHl). 

The upper sections of the larger valleys (Land System Va3) are more freely drained and the 

soils are Leached or Weakly Leached Ferruginous Tropical Soils (FnFl). In the lower parts of 

these valleys (Land System Va4) alluvial soils predominate. 

Sandy facies of the Chad Formation This group consists mainly of aeolian deposits, 

but also included are the Bama and Ngelewa Beach Ridges and their associated lacustrine sands. 

The aeolian deposits give rise to different types of terrain, varying from a relatively 

featureless plain west of Maiduguri, through irregular hummocky dunes in the northeast to 

regular, high, longitudinal dunes between Azare and Geidam. In some places fluvial activity 

has effectively altered the appearance of the dunes. Sometimes only the valleys between the 

dunes are filled with alluvial deposits; elsewhere the dunes are eroded and only remnants 

remain within alluvial areas. The sandy nature of the material is of great importance in 

determining the soil properties because the low clay content precludes the easy formation of 

pedologically significant B horizons. In these areas, rainfall is also often too low to 

allow for the movement down the profile of clay and other materials and it is not always 

sufficient for the formation of a complete drainage network. Water tends to accumulate in 

local depressions from which it evaporates, leaving accumulations of calcium carbonate and 

salts giving rise to Hydromorphic and Halomorphic Soils. These soils are particularly frequent 

in the vicinity of Lake Chad and the main river systems. Their frequency is partly 

caused by the locally higher watertable, but also by seasonal flooding of the rivers inundating 

their surrounding areas, when deposition of alluvium usually takes place. 

The general soil pattern is therefore a variable one of sandy soils alternating with 

Halomorphic and Hydromorphic Soils in the depressions. In some cases the material in the 

depressions is related to the sands; in other cases it is alluvium of quite a different 

nature. 

With increasing rainfall, the sands show a gradual increase in profile development, but in 

some places, for example where erosion has taken place, there is no soil profile development. 

In the extreme north and northeast where the rainfall is less than 500 mm (20 in) the dune 

soils show little or no profile development; they are very coarse-textured with a uniform 

brown colour (example, Gudi Series) and may be regarded as transitional between Weakly 

Developed Soils of deposition and Semi-arid Brown Soils. In the depressions there are grey, 

mottled loamy sands to sandy clay loams which contain calcium carbonate concretions and which 

have high pH and high sodium contents. These depression soils are classified as Halomorphic 

Soils. They are of very limited extent in Land Systems Vdl, Vd3 and Vd6 and are therefore 

not shown in the map symbol Wa. Land Systems Vd2, Vd7 and Vbl have a larger extent of 

Halomorphic Soils in the depressions and these systems are mapped as WaH. 

109

The soils of the Bama and Ngelewa Ridges (Land Systems Vd4, Vd5 and Vel) are sands and 

gravels, which retain their original sedimentary stratification. They are mapped as Weakly 

Developed Soils of deposition. In the southern part of the Ngelewa Ridge (Land System Ve2) 

Halomorphic Soils are relatively common in the depressions and this area is therefore mapped 

as WdH. The Halomorphic and Weakly Developed Soils are developed from the same material in 

this mapping unit (Map 3) and should not be confused with some alluvial areas (H/Wd), where 

the Halomorphic Soils are found on clayey alluvium and the Weakly Developed Soils on more 

sandy material. 

When the rainfall is more than 500 mm (20 in) per year, thin irregular bands of iron and clay 

accumulation start to appear in the dune soils. These soils vary in colour from red or brown 

on the upper slopes (example, Gulumba and Birnin Series) to brown or grey-brown on the lower 

slopes. They are classified as Non- or Weakly Leached Ferruginous Tropical Soils. In the 

south, depressions and small valleys have either brown soils with calcium carbonate concretions 

or grey mottled soils; they are classified as Semi-arid Brown Soils (example, Jigilin 

Series) and as Hydromorphic Soils respectively, but they are of limited extent only. This 

arrangement of soils (indicated by symbol Fn) occurs in the longitudinal dunefield of Land 

Systems Vc2 and Veil, as well as in the rather flat lacustrine sand area of Land Systems Vd8 

and VdlO. 

In the north the dunes are partially flooded by water from the Hadejia and Jamaare systems 

(Land System Vg2); the watertable in this area is consequently higher. Semi-arid Brown Soils, 

in association with Halomorphic Soils, occur frequently in the depressions: this area is shown 

on Map 3 as Fn/Ha. Further north, in Land Systems Vb2 and Vc8, the drainage system is 

irregular and incomplete; Halomorphic and Semi-arid Brown Soils also occur in the depressions, 

but they are not as common as in the area previously described. They are shown on the map 

with the symbol FnHa. Remnants of the longitudinal dunefield occur to the east of the Bama 

Ridge; the depressions between these dunes are filled with more recent sediments. In Land 

System Vhl these are lacustrine clays in which Vertisols are developed; this area is therefore 

mapped as Fn/Vt. In Land Systems Vh2 and Vh3 the depressions have mainly Hydromorphic 

Soils formed in alluvial deposits: Fn/Y. 

The aeolian plain between Maiduguri and Damaturu (Land System Vc2) and the lacustrine sands 

to the southeast of Maiduguri (Land System Vd9) have a slightly higher rainfall than the 

areas previously discussed. The soil parent materials are also richer in clay and the profiles 

are consequently better developed. 

The reddish yellow colour B horizon is well established and some structure can also be 

observed. There is some increase in clay content with depth, but not enough to classify the 

soils as truly Leached Ferruginous Tropical; they are therefore mapped as transitional 

between the Non- or Weakly Leached and the Leached sub-classes (Fn-1 on Map 3). The profiles 

are gradually better developed from north to south (example, Masho Series) and there is also 

a notable decrease in base saturation from north to south. Small depressions in this area 

have Calcareous or Hydromorphic Soils but are generally too small to be shown on the map. 

Some broad valleys are incised into the plain and these are filled with colluvial and 

alluvial material; in the upper reaches (Land System Vc6) the soils are generally similar to 

those found on the uplands, but some less-leached soils are likely to occur (FnFl). In the 

lower reaches of the valleys (Land Systems Vc5 and Vc9) the ordinary soil complexes of 

alluvial areas are found. 

Close to Maiduguri, in Land System Vc4, the aeolian cover is thin and discontinuous: in 

several places the underlying clays come to the surface. The soil pattern is somewhat complex 

as transitional Ferruginous Tropical Soils occur on the aeolian material while the clays 

give rise to Hydromorphic and Halomorphic Soils. This area is shown on Map 3 as Fn-l/H. 

The properties of the more important soils are summarised in Table 11. 

Lagoonal Clays 

To the south of Lake Chad lagoonal clays were laid down over an irregular sandy surface. In 

many places the clay has hardened into shale. The thickness of the clay is variable and in 

places small sandy areas emerge from the flat plain. In the south the depressions of the 

Musgowa dunefield (Land System Vhl) are partially filled by the clay and it is likely that 

the sand islands are also remnants of a dunefield. They are however modified by wind and 

water erosion and in some cases sand has been transported by wind to form new dunes which are 

found on top of the lagoonal clay. The sandy areas provide living sites and some of them 

have been artificially raised (Connah, 1966). 

110

Soil 

unit 

(Map 3) 

Clay in 

subsoil 

% 

Type of 

B horizon 

Wd 0-10 Sedimentary 

stratification 

TABLE 11 Properties of soils on sandy facies of the Chad Formation 

Colour Mottling 

White to 

light 

grey 

Wa 0-10 None Pale 

brown 

Concretions 


CEC Sat ESP 

PH 

topsoil subsoil 

Organic 

carbon in 

topsoil 

% 

None None None - - - 7.0-8.0 7.5-8.5 0.1-0.5 

None None None - - - 6.5-7.5 7.5-8.5 0.1-0.3 

Fn 0-10 Lamellae Reddish None None None - 35-70 0-2 6.0-8.0 5.5-7.0 0. 1-0.3 

(upper 

slope) 

yellow 

Fn 

(lower 

slope) 

5-15 Lamellae Very pale 

brown 

Fn-1 15-25 Colour B Reddish 

yellow 

A 15-25 Moderate 

Textural B 

H 10-30 Variable Light 

grey to 

grey 

brown 




Common Few Locally 35-60 40-100 0-3 6.0-8.0 5.5-9.0 0.1-0.3 

None None Locally 20-40 40-100 0-3 5.0-7.0 5.5-7.0 0.2-0.6 

Brown None None Many 50-100 100 1-6 6.0-7.5 8.0-9.0 0.1-0.3 

Common 

to 

many 

Few Common to 

many 

40-100 100 >10 6.5-8.5 8.5-10.0 0.1-0.4

The clay content of the soils is nearly always greater than 40 per cent and frequently 

exceeds 50 or even 60 per cent (example, Ngala Series). All these clay soils crack severely 

during the dry season, but not all can be classified as Vertisols, as by definition Vertisols 

have at least 30 per cent clay and show phenomena such as gilgai or slickensides. According 

to an older definition (USDA Soil Survey Staff, 1960), they should also have an exchange 

capacity of at least 30 meq per cent soil. This appears to be a useful property in the area 

under discussion, for, where the exchange capacity is below 30 meq, slickensides or gilgai 

are not observed and the soils are mottled and often contain iron or manganese concretions 

(example, Dougouma Series). These mottled soils are classified as the vertic sub-group of 

the Hydromorphic Soils. Both the true Vertisols and the Vertic Hydromorphic Soils in this 

area frequently contain calcium carbonate concretions and they consequently have a pH ranging 

between 7 and 9. The amount of sodium present in the soils is higher than in many other 

soils, but sodium rarely occupies more than 10 per cent of the exchange complex and structures 

characteristic of Halomorphic Soils have not been seen. 

The soils of the sand islands are completely different. They are pale brown fine sands without 

profile development. Because of their recent reworking they are considered younger than 

other dune soils, which show seme profile development. They are classified as Weakly 

Developed Soils of deposition. In the transition zone between the sand islands and the clay 

there are shallow sandy clays overlying sand. 

Three main soil patterns exist (see Figure 13): Vertisols with Weakly Developed Soils of 

deposition (VtWd) in the areas of lagoonal clays with sand emergents of Land Systems Vjl and 

Vj3; Vertisols (Vt) in uniform clay areas (Land System Vj2); and Vertic Hydromorphic Soils 

(Yv) in Land System Vj4. 

The properties of the various soils are summarised in Table 12. 

Alluvial Deposits 

Alluvial soils are found along nearly all streams and therefore in nearly all land systems. 

Often they are of very limited extent and cannot be mapped separately. In many other cases 

however the alluvial deposits are extensive enough to warrant mapping as a separate unit. 

Particularly large alluvial areas are found along the Hadejia river, in the delta deposits of 

the rivers Yedseram and Alo and along the river Benue. The properties of these soils can be 

very variable over small distances. 

The nature of the deposits along the smaller steams depends largely on the rocks traversed by 

them. For example, a stream flowing through a shale area but rising on sandstone will have 

sandy deposits, while a stream which has the larger part of its catchment on shales and mudstones 

will be characterised by more clayey deposits. 

The basic pattern of alluvial deposits (Figure 14) is similar all over the world (Edelman and 

van der Voorde, 1963). Near the present and former river beds natural levees occur which are 

normally sandy to loamy in character. They occupy the highest part of the terrain; behind 

them are depressions, which may be flooded for a considerable time and where lakes form a 

common feature. These areas, known as backswamps, have generally fine-grained deposits. 

The pattern is not always so simple, mainly because of changes in the course of the river. 

As the river gradually changes its course a complex of levees is built up. In the Hadejia 

river area and in the deltas of the Yedseram and the Alo the streams do not always have a 

definite course and the picture is even more complex, as illustrated in Figure 10. 

The river beds normally consist of coarse or fine sand and this material can hardly be classified 

as soil. The levees have sandy to loamy material in which the original stratification 

is often clearly seen. The levee soils are well to moderately well drained and can be classified 

as Weakly Developed Soils of deposition. 

The backswamps have fine-textured soils in a flat topography. The soils are therefore 

poorly drained, normally grey in colour and mottled to the surface. Some of them crack 

severely when dry and can be regarded as the vertic sub-group of the Hydromorphic Soils 

(example, Lamido Series). In the basins of the Hadejia, Gana, Yobe and Yedseram river 

systems the basin soils have high sodium contents and sometimes high salinity as well; they 

are classified as Halomorphic Soils (example, Adi Series). The basin soils of the Alo delta 

and of some of the smaller rivers normally contain calcium carbonate concretions but do not 

have high sodium content or a high salinity; they are therefore still classified as 

Hydromorphic Soils. It appears that Halomorphic Soils occur in alluvial complexes of rivers 

originating in Basement Complex areas. It is likely that some of the granites of that complex 

provide a source of sodium. 

112

Soil 

unit 

(Map 3) 

Vt 

Yv 

Wd 

Clay 

% 

50-80 

35-70 

0-10 

B horizon Colour Mottling Structure 

None 

None 

None 

Dark grey 

Dark grey 

brown 

Pale brown 

Pew 

Many 

None 

CEC: Cation exchange capacity in meq % clay/soil 



TABLE 12 Properties of soils on lagoonal clays 

Strong 

prismatic 

Strong 

prismatic 

No 


iron carbonate soil clay 

None 

Common 

None 

Pewcommon 

Common 

None 

30-40 

15-30 

40-50 

35-45 

Sat ESP 

80-100 

80-100 

5-10 

0-10 

pH 

topsoil subsoil 

7.0-8.0 

6.5-8.5 

6.0-7.0 

7.0-8.5 

6.5-9.0 

6.5-7.5 

Organic 

carbon in 

topsoil 

% 

0.3-2.0 

0.3-1.5 

0.1-0.3

Soil patterns on sandy facies of Chad Formation Figure 13 

Mapping Units Wa WaH Wd Yo Lake 

Chad 

^.S^S?!^^ 

Dunes with few Halomorphic soils in depressions Dunes with frequent Halomorphic soils Beach Ridge 

in depressions 

Mapping Units Fn(FnHa) Fn/Ha 

Birnin Series 

r:ï^î;?~S5&Ss: ; 

Mapping Units Fn-I 

Benisheikh Serie 

Jigilin Series ^^rrr-^ Adi Series 

^^^^•f;iij-l-:l : }^^^^^î^^M'M^. 

Dunes sand, soils with weak profile development 

Aeolian plain with weakly to moderately well developed soils 

Soil patterns on lagoonal clays 

•;~?*JltfZ~jj •^>;--Ä^ 7 ^S=" i ii^ 

As Fn, but with many 

Halomorphic soils in depressions 

FnFI 

Valley • infill of sandy soils with 

variable profile development 

Mapping Units Fn/Vt Vt/Wd Vt Vt/Wd 

^^l^gll^^^J^^^^ 

Longitudinal dunes with day in depressions 

Non-Leached Ferruginous Tropical soils and 

D.O.S. 3099 N 

Cby plain with sand islands 

Vertisols in plain 

Weakly developed soils on 

aeoiian material 

114 

Fn-I 

Clay plains 

mostly Vertisols 

sometimes vertic 

Hydromorphic soils 

Vt 

Shale

c Complex delta area near Bama 

D.O.S. 3099 P 

A* - 

Swamps 

Soil patterns in alluvial areas Figure 14 

• i

Most of the alluvial areas are represented on Map 3 as combinations of Weakly Developed 

Soils of deposition with either Hydromorphic Soils (Y/Wd) or Halomorphic Soils (H/Wd). The 

soil patterns in Land Systems Vfl, Vf2, Vf3 and Vf5 are extremely complex because they consist 

of eroded dunes surrounded by alluvial deposits. Both the dunes and the sandier alluvial 

materials have Weakly Developed Soils of deposition, while on the finer-textured 

material there are both Halomorphic Soils and Vertisols. This complex is shown on the map 

with the symbol Wd/Hv. 

In some parts of the Yedseram alluvial complex nearly all the soils are Halomorphic (Land 

Systems Vi5, Vi7 and Vi9); in the higher areas these are leached (HI), mostly of the 

Solodised Solonetz variety and in the backswamp (example, Limanti Series) the Vertic 

Halomorphic Soils (Hv), are common. 

In the Giwano Plain (Land System IIa6) a thick layer of clay has been deposited, probably by 

an old course of the river Gongola. On this material true Vertisols are developed (Vt) 

(example, Giwano Series). A special group of soils is found along the border of Lake Chad 

(Land System Ve3). These soils contain remnants of the aquatic and semi-aquatic vegetation 

and they are rich in organic matter; they are classified and mapped as Organic Hydromorphic 

Soils (Yo). 

CORRELATION WITH SOILS OF NEIGHBOURING COUNTRIES 

The soil classification system used in this report is based on that of Aubert (1965) in 

order to facilitate correlation with neighbouring countries. A soil map of the eastern part 

of Niger, at a scale of 1:500 000, was published by Bocquier and Gavaud (1964) and a soil map 

of Eastern Cameroon, at a scale of 1:1 000 000, by Martin and Segalen (1966). 

In general the correlation of soil boundaries and classification units across the international 

frontiers is good. There are however some small discrepancies, which are caused by 

differences in interpretation of the classification system, different ways of representing 

soil complexes and differences in the amount of information available. 

In Niger the dune soils are regarded as transitional (intergrade) between Weakly Developed 

Soils of deposition and either Non- or Weakly Leached Ferruginous Tropical Soils or Semi-arid 

Brown Soils. In Nigeria the dune soils with lamellae formed under a rainfall higher than 

500 mm (20 in) are mapped as Ferruginous Tropical Soils and not as intergrades. On both 

sides of the frontier Halomorphic Soils are included in the dunefields, but in Niger more 

detail is shown and mention is made of soils with a (sulphate) salt crust. 

Some alluvial areas are classified as complexes of Weakly Developed Soils, Halomorphic Soils 

and Vertisols. The cartographic representation of this complex is different on either side 

of the frontier: in Niger all 3 components are indicated, but in Nigeria only the 2 most 

important categories are shown. 

In Cameroon, Martin and Segalen map Halomorphic Soils with Vertisols to the south of Lake 

Chad, but Halomorphic Soils have not been observed in the corresponding portion of Nigeria. 

Further south the map of Cameroon shows Vertisols, while the adjacent area in Nigeria is 

mapped as the vertic sub-group of the Hydromorphic Soils. The soils crack deeply during the 

dry season and have a strong prismatic structure, but the characteristic properties of 

slickensides or gilgai are missing. These soils cannot therefore, in our opinion, be classified 

as Vertisols. 

In Cameroon, the Mandara hills have been divided into areas with mostly Raw Mineral Soils and 

areas with mostly Weakly Developed Soils of erosion. Such a division has not been attempted 

in Nigeria. The red tropical soils reported just east of the border near Mubi (Martin 

et al., 1966) have not been found in Nigeria. 

In the above paragraphs only the differences have been emphasised and explained. If, however, 

the maps of the 3 territories are compared there is a very good agreement. 

CORRELATION WITH OTHER SOIL CLASSIFICATION SYSTEMS 

Although the French classification system is the most widely used in West Africa, it is 

desirable to attempt to correlate the soils of North East Nigeria with some other important 

and widely used classification systems. These are the systems of the United States 

Department of Agriculture and the system designed for the World Soil Map (Dudal, 1968; 1969). 

116

The American system was first published in its 7th Approximation (USDA Soil Survey Staff, 

1960), while a revision was distributed in 1967 (USDA Soil Survey Staff, 1967). The 7th 

Approximation introduced an almost completely new set of names for the great soil groups and 

also introduced a number of diagnostic horizons. A disadvantage of the system is that the 

definitions are often complicated and difficult to apply to tropical conditions. The system 

for the World Soil Map (referred to as the World system) uses many of the basic concepts of 

the American system, but the descriptions and definitions are very much simpler. 

The supplement to the 7th Approximation introduced soil temperature and soil moisture as 

distinguishing characteristics at a high level of the classification. However, in reconnaissance 

surveys in the developing countries it is almost impossible to obtain measurements 

of these factors. In the present report some soils have arbitrarily been placed in the 

Ustic or Tropic subdivisions wherever this was relevant. An Ustic soil climate has limited 

moisture but this is available during the optimum growing season. The soil is dry for more 

than 90 cumulative days, but moist for 180 cumulative or 90 consecutive days. In a tropic 

soil climate the mean soil temperatures are 8°C (47°F) or more, and there is less than 5°C 

(9°F) difference between mean summer and winter soil temperatures. 

In the following paragraphs a correlation of the different classification systems is 

attempted for the soils of the area under review. This correlation is done by checking the 

definitions of the various systems against the field and laboratory data of the soils rather 

than by comparison of the different definitions. 

Weakly Developed Soils of erosion are limited in depth to 30 cm (12 in) by hard rock. They 

can be closely correlated with the Lithosols of the World system, which puts the depth limitation 

at 25 cm (10 in). Most of these soils will belong to the Eutric group which has a pH 

of 5.5 or more. In the American system the shallow soils are not separated at a high level; 

lithic sub-groups are established for soils with hard rock at a depth of 50 cm (20 in) or 

less. 

Weakly Developed Soils of deposition may be alluvial or aeolian in origin. The sandy alluvial 

soils can be compared with the Eutric Fluvisols of the World map. In the American 

system they would probably be classified asAquicor Typic Ustipsamments and Ustifluvents. 

They would be Psamments if their texture were coarser than loamy fine sand, and Fluvents if 

the texture were loamy fine sand or finer. 

The aeolian dune soils have little or no profile development. In the French classification 

they are regarded as Weakly Developed Soils of deposition, transitional to Semi-arid Brown 

Soils, or, if they have lamellae, as Non- or Weakly Leached Ferruginous Tropical Soils. In 

the World system the first can be correlated with the Eutric Rhegosols and the latter either 

with the Eutric Rhegosols or with the Laminic Arenosols. In the American system the first 

would be classified as Typic Torripsamments or Typic Ustipsamments, depending on whether they 

were moist for less or more than 90 consecutive days. The soils with lamellae would be 

classified as Alfic Ustipsamments. 

The correlation of the Vertisols is relatively simple as the 3 systems all use the same terminology 

at the highest level. In the original version of the American classification the 

Vertisols were subdivided into Aquerts and Usterts on the basis of colour and mottling. This 

was followed by both the French and the World systems. The Vertisols of lithomorphic origin 

can therefore largely be correlated with the Chromic Vertisols and the topomorphic Vertisols 

with the Pellic Vertisols of the World system. In the American system however climatic 

factors once again have been introduced at high level and the term Aquert has been abolished. 

The 2 categories can now be correlated with the Chromusterts and the Pellusterts. 

The Semi-arid Brown Soils are not very extensive and information about them is limited. They 

have been tentatively correlated with the Calcaric Cambisols of the World system and with the 

Typic Ustropepts of the American system. 

The Eutrophic Brown Soils are characterised by a well structured surface layer which is rich, 

in organic matter. This layer fulfils the requirements laid down in the American system for 

the 'mollic epipedon' and the soil can therefore be classified as a Mollisol. At group level 

the classification is Haplustoll: shallow stony soils can be correlated with the Lithic 

Haplustoll, while the others are Udic Haplustolls, or when they have vertic properties, 

Udertic Haplustolls. In the World system the surface layer would be called a 'melanic A 

horizon' and the soil can be correlated with the Haplic Phaeozems. 

For the correlation of the Ferruginous Tropical Soils the base saturation and the presence of 

a textural B horizon are important criteria. The soils with a textural B horizon and a base 

saturation of more than 35 per cent can generally be correlated with the Alfisols of the 

117

American system and the Luvisols of the World system. They would be correlated with Ultisols 

and Acrisols, if the base saturation was less than 35 per cent. In the area under review 

this is not normally the case. 

Most of the Leached Ferruginous Tropical Soils of the area can be correlated with the Ustalf 

sub-order of the American system. At group and sub-group level the soils with many concretions 

or with concretionary ironpans are equivalent to the Plinthustalfs. The soils with few 

or no iron concretions are comparable to the Haplustalfs. Those developed on Basement Complex 

or on Cretaceous sandstone are Typic or Udic Haplustalfs if the base saturation of the 

B horizon is more than 75 per cent and Ultic Haplustalfs if the base saturation is less than 

75 per cent. Most of the ordinary Leached Ferruginous Tropical Soils are not sufficiently 

mottled to place them in the sub-group of the Aquic Haplustalfs. The Hydromorphic sub-group 

of the Leached Ferruginous Tropical Soils can almost certainly be correlated with the Typic 

or sometimes with the Vertic Tropaqualfs. 

For the World system the concretionary Leached Ferruginous Tropical Soils can be correlated 

with the Plinthic Luvisols and most of the ordinary Leached Ferruginous Tropical Soils with 

the Orthic Luvisols. The hydromorphic sub-group would be largely equivalent to the Gleyic 

Luvisols, but some of them may be regarded as at least transitional to the Ochric Planosols. 

In most cases the contrast between the eluvial and illuvial horizons is not sufficient. 

The classification of the Leached Ferruginous Tropical Soils on poor material, as found over 

the Kerri Kerri Sandstone, forms a special case. It has already been stated that these soils 

have undergone different soil-forming processes in the past, which may have caused the formation 

of very thick textural B horizons. They can be correlated with the Oxic Paleustalfs of 

the American system. The prefix pale (o) indicates their old age, while the sub-group name 

oxic indicates the transition to the Oxisols, which are the American equivalent of the 

Ferrallitic Soils. In the World system they can be correlated with the new unit of the 

Nitosols, which are defined as having a deep argillic (= textural) B horizon, low clay 

activity and diffuse upper and lower boundaries. As the base saturation is generally below 

50 per cent, they belong to the Dystric group of Nitosols. 

The correlation of the Non-Leached Ferruginous Tropical Soils has already been discussed 

together with the Weakly Developed Soils. The soils which are transitional between Non- 

Leached and Leached are regarded as soils in which the soil-forming processes are not far 

advanced. They have a B horizon which differs sufficiently in colour and structure from the 

parent material to call it a 'cambic horizon' , but there is no or little accumulation of 

clay. These soils can be correlated with the Typic Ustropepts of the American system and 

with the Eutric Cambisols of the World system. 

The Halomorphic Soils are divided into leached and non-leached sub-orders. The Leached 

Halomorphic Soils have a textural B horizon which has an exchangeable sodium percentage of 

more than 10 per cent. The American nomenclature requires at least 15 per cent exchangeable 

sodium before such an horizon can be called natric, but some authorities consider this limit 

to be too high. Most of the Leached Halomorphic Soils could be correlated with the 

Natrustalfs of the American system and with the Ochric Solonetz of the World system. It is 

noteworthy that the main diagnostic feature in the American system is the textural B horizon, 

while in the World system and the French classification the sodium hazard is considered more 

important. 

The Non-Leached Halomorphic Soils can probably be correlated with the Halaquepts of the 

American system and with the Gleyic Solenetz of the World system. 

Many of the ordinary Hydromorphic Soils are found in alluvial areas; they can easily be correlated 

with the Eutric Fluvisols of the World system. In the American system they can be 

correlated with the Fluventic Tropaquepts, although some may belong to the Vertic Tropaquepts. 

The Organic Hydromorphic Soils of the shores of Lake Chad could be classified as Humic 

Gleysols in the World system and as Histic Tropaquepts in the American system. 

The Vertic sub-group of the Hydromorphic Soils is most similar to the Vertic Cambisols of the 

World system and the Vertic Tropaquepts of the American system. 

These correlations are summarised in Table 13. 

118

TABLE 13 Correlation of soil classification systems 

French System World Map System American System 

Weakly Developed Soils 

of erosion 

of deposition (alluvial) 

transitional to Semi-arid 

Brown Soils (aeolian) 

Vertisols 

topomorphic 

lithomorph 

Lithosols 

Eutric Fluvisols 

Eutric Rhegosols 

Pellic Vertisols 

Chromic Vertisols 

Lithic sub-groups 

Aquic ) Usti. ( fluvents 

Typic ) ( psamments 

_ . ( Torri- ) 

Typic ) usti- ) P samments 

Pellusterts 

Chromusterts 

Semi-arid Brown Soils Calcaric Cambisols Typic Ustropepts 

Eutrophic Brown Soils Haplic Phaeozems Udic ) 

Lithic ) Haplustolls 

Vertic ) 

Ferruginous Tropical Soils 

Non-Leached 

Non-Leached - Leached 

Leached, nonrconcretionary 

Leached, on poor material 

Leached, concretionary 

Leached, hydromorphic 


Leached 

Non-Leached 


Normal 

Organic 

Vertic 

( Laminlc Arenosols 

( Eutric Rhegosols 

Eutric Cambisols 

Orthic Luvisols 

Dystric Nitosols 

Plinthic Luvisols 

Gleyic Luvisols 

Ochric Solonetz 

Gleyic Solonetz 

Eutric Fluvisols 

Humic Gleysols 

Vertic Cambisols 

119 

Alfic Ustipsamments 

Typic Ustropepts 

Ustic, Typic, Udic Haplustalfs 

Oxic Paleustalfs 

Plinthustalfs 

Typic or Vertic Tropaqualfs 

Natrustalfs 

Halaquepts 

Fluventic Tropaquepts 

Histic Tropaquepts 

Vertic Tropaquepts

^Ä~--«dß 

Ä'i;'?£^!&JE2 

^Js-j£**Z?f'*"~ 

PLATE 1/9 Near Gulumba. Termitaria on heavy soils in Land 

System Vil, the Yaribi Delta. March 1967. 

-'•IE' - 

««- 

.-tut*? ^t —*^\. ,— #_'-*-. ; - • * I .* rlHka^Â-. 

*ä^3r< 

-.-==-.~a* 

^- ; '^^^^B£^c^^ ^f^ 

"^V^**» v 

PLATE 1/10 Soil erosion at the western foot of the Biu 

Plateau resulting from intensive utilisation 

of Ferruginous Tropical Soils derived 

from rocks of the Basement Complex. 

120 

•-A

PREAMBLE 

VEGETATION 

by 

P N de Leeuw and P Tuley 

The relationship of the West African vegetation to the main east-west orientated eco-climate 

zones has been widely reported (Chevalier, 1900; Keay, 1953) and such terms as Guinea, Sudan 

and Sahel Zones, or their French equivalents, figure largely in environmental descriptions. 

Often, there is confusion as to whether the terminology is being applied to vegetation, to 

climate or to some broader geographical concept. It is perhaps in the last sense that the 

terms should be used and an attempt has therefore been made to classify the vegetation of 

the project area in terms of recognisable plant communities. The primarily herbaceous 

communities, the Aristida/Andropogon and the Sorghum grasslands and the herbaceous communities 

(17 in all) associated with the woody communities, are described and mapped separately 

in Volume 4. This has been done to keep together all aspects of rangeland ecology and 

management in the same volume. Those dealt with here are therefore the arboreal communities. 

Despite the multivariant nature of the environmental influences associated with the differing 

plant communities, a basic understanding of the vegetation types and their distribution in 

the project area can be obtained from consideration of only three prime environmental 

factors, climatic, edaphic and anthropic. 

THE RELATIONSHIP WITH CLIMATE 

A close relationship exists between the zones described in the section on climate and the 

non-hydromorphic vegetation. In the north, where the mean annual rainfall (m.a.r.) falls 

between 250 mm (10 in) and 500 mm (20 in), lies the belt of acacia-dominated Tree and Shrub 

Savanna and its anthropic derivatives. The central sector of the project area witha m.a.r. 

falling between 1 000 mm (39 in) and 500 mm (20 in) carries a belt of woodlands and anthropic 

derivatives dominated by species of the family Combretaceae. Annual rainfall much in excess 

of 1 000 mm (39 in) is restricted in the project area but, as this level is approached and 

exceeded, the combretaceous woodlands are replaced by ones dominated by species of the family 

Leguminosae. The characteristics of the so-called Sub-Sudan Zone have been discussed in the 

section on climate. This complex climatic pattern occurring at the critical rainfall level 

between 900 mm (35 in) and 1 000 mm (39 in) is reflected in the nature of the vegetation of 

the area. A high proportion of 'intergrade communities' are to be found, intermediate in 

species composition between typical Sudan and Northern Guinea Zone communities. There are 

also rapid changes in the vegetation pattern and localised pockets of plant communities 

atypical of the surrounding vegetation. 

The effects of altitude in the project area appear to be largely confined to the influences 

on rainfall pattern. Despite the gross *blanketing' rain shadow effect of the Jos/Bauchi 

Plateau, subsequent orographic influences are still effective enough to produce secondary 

rain shadows and, particularly in the south, elevated areas tend to carry a 'wetter' vegetation 

on their westward/northwestward windward slopes. Although parts of the Mandara range 

rise to 1 200 m (4 000 ft), the effects on vegetation do not appear to be as marked as those 

found on elevated areas to the south and west. However, the highlands have typically been 

subjected to a high level of utilisation which may mask the altitude effect, and collections 

of 'upland' species are recorded in the literature (Letouzey, 1968). The Zummo Mountains 

appear to be something of an exception and probably merit further botanical investigation. 

THE RELATIONSHIP WITH SOILS 

The experience of Ramsey and de Leeuw (1966) is typical of the survey area as a whole, in 

that the overriding edaphic factor is soil-water. With the exception of the effects of 

salinity discussed below, in virtually every case investigated the distribution of the 

vegetation can be equated with soil/water relationships. In certain areas, where for example 

121

direct impedence to root growth by concretionary ironstone or subsurface rock occurs, there 

may be doubt as to which effect predominates but, by and large, the concept holds true 

throughout the survey area. On freely draining soils the relationships with rainfall are 

readily identifiable while the communities on heavy clays and similar soils span a wider 

climatic range. Perennially wet communities are extremely similar throughout the project 

area. In any climatic grouping, three edapho-nodal communities can usually be identified, 

associated with skeletal stony soils:: sands, sandy loams, and clay soils. Intergrade 

communities can usually be typed in terms of intermediate properties of the soils. 

Hill and steep-slope vegetation often presents problems in description and the application of 

an appropriate mapping unit. Usually such areas are not intensively investigated and are 

often mapped as carrying some form of thin soil' community. In many locations this is a 

valid classification but it by no means always holds true. The term 'Inselberg Community' 

has been coined to describe the situation where large expanses of exposed, sometimes smooth, 

rock occur. Typically in such circumstances a low annual or perennial 'cushion' community is 

found on the rock faces, while the deep and often fertile soils of the interrock crevices and 

pockets carry well developed woodland, sometimes with elements of the riparian communities 

found in the area. Tall and lush grasses are also typical of such sites. Thin soil' 

communities may also occur in close proximity to the better developed rock sites. 

In the survey area, salinity is invariably associated with the heavier soils. A large 

proportion of the clay soils has at least some tendency towards halomorphism, the extent of 

which is reflected in the vegetation, or in extreme cases the near absence of vegetation. 

THE RELATIONSHIP WITH MAN 

Throughout much of the area, the form of the vegetation is largely a reflection of the impact 

of man and his livestock. The resultant 'secondary* communities are extremely variable both 

in form and ecological status. They can vary from apparently stable disclimaxes to serai 

communities, the nature of which depends on the point in time of the observations, in a cycle 

of regeneration from utilisation to full regrowth. In consequence, it is often difficult to 

find a satisfactory classification for them but, in view of their importance, an effort must 

be made to present as clear a botanical and spatial picture of them as possible. Farming and 

stock-rearing activities in the area are described in Volume 4 and for the purpose of this 

section the results of the whole range of activity, burning, cultivating, grazing, trampling 

and so on, are considered together. The descriptive and mapping units selected fall into two 

main categories. 

1. Parklands. These are typically areas of intensive and/or long-standing cultivation. The 

cover is largely fallow regrowth of herbaceous species with a few highly persistent shrubs. 

Scattered mature trees, usually of economic value, give this unit its characteristic 

appearance. 

2. Tree and Shrub/Shrub Savannas. These are typically derivatives of a lower level of 

impact, such as shifting and cyclic cultivation and open-range grazing. 

Cultivation in the broadest sense can be equated with desiccation and heavily cultivated 

areas in a wetter regime often have the appearance of lightly cultivated areas in a drier 

one. This feature often presents problems, particularly in the Sub-Sudan areas where it is 

often not possible to determine if the presence of Sudan-like conditions is due to longstanding 

cultivation or to climate. The matter is further complicated in that drier areas 

tend to have fewer human and animal disease problems and hence tend to attract the cultivator 

and pastoralist. 

CLASSIFICATION OF PHYSIOGNOMIC TYPES 

The physiognomic terminology employed in this report is essentially that laid down at the 

Yangambi Meeting (CCTA/CSA, 1956). Despite subsequent objections from East African workers 

(Pratt et al., 1966), the terms are in such common usage and are so widely recognised in West 

Africa that their retention is advisable until some universally accepted scheme is available. 

122

METHODOLOGY 

The data upon which the proposed plant communities occurring in the project area are based 

have been generated from three main sources. First, records of presence and abundance of 

species largely collected in the course of the surveys described in the section on soils, 

some of which data have been subjected to statistical analysis (Ramsay and de Leeuw, 1965). 

Second, vegetation records and field notes collected by the authors. Third, interpretation 

and extrapolation of published data applicable to the project area. A list of the last is 

available in Posnett et al. (1971). 

CLASSIFICATION OF PLANT COMMUNITIES 

The study of phytosociology, defined by Lambert and Dale (1964) as 'the study of plants as 

gregarious entities', has led to differing systems of recording, describing and classifying 

plant communities. These differences are understandable in view of the diversity of both the 

vegetation being observed and the objectives of the observers. Without entering into the 

merits and disadvantages of the various approaches to vegetation study it appears clear that 

the concept of 'associated species', namely, a near-constant grouping of species that tends 

to occur under the same environmental circumstance, is fundamental to all. In more recent 

times the emphasis on delineating well defined and often 'rigid' plant communities has 

diminished, even in such an orthodox school as that of Braun-Blanquet, partly due to many 

vegetation surveys being conducted in regions where the knowledge of the local flora was 

inadequate. The concept of faithful and characteristic species is best adopted for 

distinguishing plant communities in areas where the local flora is well known and where there 

is an adequate fund of related environmental data. This view was recently expressed by 

Doing (1970). 'It should be admitted openly that new vegetation units must be primarily 

based on other criteria than faithful and differential species and that a direct link between 

species and vegetation types generally does not exist. An intermediate category between both 

abstract units: the sociological species group, seems necessary'. Zonneveld (1970) coined 

the term 'ecological group of species' as a group of plant taxa sharing the same habitat in a 

greater degree than expected if the taxa were randomly distributed. At the same time the 

group should have a statistical correlation with a measured or estimated environmental 

factor. The term 'sociological group' is proposed when no such statistical correlation has 

been established. 

The plant communities described here can be defined as plant associations in the generally 

accepted sense or a combination of 'ecological groups of species' and 'sociological groups' 

as defined by Zonneveld. In addition, the descriptions provided are largely 'nodal' in 

character in the sense of Poore (1955). The format is aimed at providing a clear definition 

of the typical land facet/climate/plant community relationship to allow ease of presentation 

in the land system descriptions in Volume 3. These nodal groups of species can be considered 

as assemblies of associated species which are adapted to a specific range of climate, edaphic 

and anthropic factors. They also serve as concise mapping units for the accompanying 

vegetation map (Map 4). However, within the survey area, intermediate environmental circumstance 

gives rise to 'intergrade plant communities' intermediate in character between the 

main nodal formations. Where such communities are spatially important, they are also 

described and mapped. 

It should be noted that even the major nodal units are not all of the same ecological status. 

For example, the leguminous woodlands of the higher rainfall areas and the Acacia Tree 

Savannas of the far north can probably be considered as approaching a climax vegetation while 

the great belt of combretaceous woodland across the centre of the area is probably a 

disclimax. 

In Tables 14 to 25 an attempt has been made to design a visual presentation of the species 

composition of the major plant communities of the project area. 

In Figure 15, the communities are spatially arranged, in terms of their environmental 

relationships. In general terms the circles represent near 'natural' units while the squares 

are anthropic derivatives. In the tables the communities are arranged as closely as possible 

to the sequence shown in Figure 15. 

123

Edaphic Factors 

LITHOSOLS 

DEEP, FREELY 

DRAINING SOILS 

IMPERFECTLY 

DRAINED SOILS 

(HYDROMORPHIC) 

IMPERFECTLY 

DRAINED SOILS 

(VERTIC) 

IMPERFECTLY 

DRAINED SOILS 

(HALOMORPHIC) 

Climatic Factors 

Environmental relationships of the major woody plant communities Figure 15 

SAHEL 

33 

? 

34 

^ (§> 

© 

26 

*—' 

24 

29 

-?- 30 

28^29 

SUDAN. SUB-SUDAN NORTHERN GUINEA 

® © 

25 

£® 23 

20, 

0 

© © 

12 4 ^—=. 7 ^=5 5 

©^HÏ^Kjo) ^ {jT| © 

RIPARIAN/SWAMP 

SOILS O 

D 

D.O.S. 3099 O 

Anthropic links 

Savanna woodlands 

& tree savannas 

Shrub savannas, 

fallows & parklands

Alluvial complexes - woody vegetation 

Schematic relationship of the major plant communities 

31. 32 & 33 36b 36b 36b 27,28 & 29 36a & 29 

Figure 16 

^j>^?ör A ?yy _T^f_ 

Dunes and remnant sand plain Grass swamp with Main channel 

wet sand islands and levees 

Northern Alluvial Complex 

Clay plain Sand islands 

37a 37d 37d 37b 37c 10. 16, 17.18.27 & 28 

Flood plain Rock outcrops Main channel Wooded Raised areas with 

and denuded banks levee high water table 

Southern Alluvial Complex 

? f y ? 

Clay flat 

38d 38b 38a 38c 

mlJ1! »wys/wtfw>M('j!r 

Incised tributary Stream Main channel 

bank 

D.O.S. 3099 R 

Grass/sedge swamp Main channel Stream bank 

and "Fig Island" 

Deji/Gaji Complex 

125 

Upland

The Species List * 

The species list has been made as complete and representative as possible of the woody plant 

life in the project area. It has however proved necessary, due to limitations of space, to 

omit certain species that the authors would otherwise have liked to include. Examples of 

these are' Cochlospermum spp., so very typical of lithosplic sites; Asparagus spp., 

Adenium honghel and Euphorbia unispina, sometimes very prominent locally on heavy clays, 

particularly in the south of the project area; and in the rich flora (unique to the area) of 

the Deji/Gaji Complex only a representative sample of species is shown in the list. 

An attempt has also been made to arrange the species in environmentally related groupings. 

With some species this is relatively easy to do but others could be placed in two or more 

categories. Where this occurs, as for example Khaya senega lens is which could just as 

readily be placed under riparian species as farm and fallow ones, the species has to be 

arbitrarily placed in one category only. 

In the tables four communities can be accommodated on each page. Within each there are four 

'abundance classes' and a diagonal line represents the presence of a species. 

Alluvial Complexes 

In order to obtain a reasonable mapping unit, all communities associated with the river 

systems have been grouped into three complexes. The component communities of the complexes 

are however defined in the following tables and their generalised relationships are shown in 

Figure 16. The vegetation associated with the tributaries entering the Gongola at its 

northern extremity is shown in Map 4 as being of the Southern Alluvial Complex. It does 

however have many unique features and is probably best considered as an intermediate with 

the Deji/Gaji Complex. 

* Note on spelling. The spellings of the genera (e.g. Ziziphus and Annona) used here were derived from 

The Flora of West Tropical Africa by J. Hutchinson and J. M. Dalziel (Second ed.) 1963, London: 

Crown Agents and not from the Index Kewensis. 

126

v* :u pf-4 fpcf 

PLATE 1/11 Typical Anogeissus Woodland south of Damboa. 

March 1967. 

PLATE 1/12 Lannea humilis. A typical gregarious clump 

showing the low contorted habit. 

127

1 APRORMOSIA/DETARIUM WOODLAND/TREE SAVANNA - BüRKEA VARIANT 

Physiognomy Open to dense savanna woodland, standing 10-15 m (33-50 ft) high, with usually a well 

developed understorey of shrubs. 

Dominant 

floristics 

Environmental 

relationships 

Characterised by the presence of such typical Northern Guinea species as Afrormosia, 

Detarium, Burkea, Tetrapleura, Cuasonia, Afzelia, Isoberlinia, Swartzia, 

Adenodolichos, Hymenocardia and Daniel Iia. 

The characteristic woodland in the project area where Northern Guinea or near Northern 

Guinea conditions occur on free-draining to lithosolic sites. It probably reaches 

maximum development in parts of the Wawa Bush (Land Systems Illbl and IIIb2) and in 

some parts of the Gombi Plain (Land System Ibl). 

Species list Based on a typical 0.2 ha (0.5 ac) plot in the Wawa Bush (Table 14. Column 1). 

2 APRORMOSIA/DETARIUM WOODLAND/TREE SAVANNA - DETARIUM VARIANT 

Physiognomy Similar to (1), usually somewhat lower in height. 

Dominant 

floristics 

Environmental 

relationships 

Similar to (1), but with Detarium more predominant. Crossopteryx is a conspicuous 

shrub. 

Of similar climatic distribution to (l), but more typical of stony sites and drier 

conditions generally. 

Species list Based on traverse in the Song area of Land System Ic3 (Table 14, Column 2). 

3 APRORMOSIA/DETARIUM WOODLAND/TREE SAVANNA - ISOBERLINIA VARIANT 

Physiognomy Similar to (1), the canopy typically more closed and the stand denser. 

Dominant 

floristics 

Environmental 

relationships 

Similar to (1), but with the conspicuous presence of Isoberlinia spp. often in pure 

gregarious stands. The species list records the presence of /. doka but a proportion 

of this is I. dalzielii wrongly identified. On the pediments of the Mandara range 

(Land System Ic2) occurs a variant Isoberlinia/Anogeiasus Woodland. It contains many 

elements of the Terminalia/Combretum Shrubland (Communities 4 and 5) and significant 

numbers of emergent tree species usually associated with farmland such as 

Butyrospermum, Parkia, Ficus spp., and Tamarindus. It would appear to differ from the 

more typical type due to past anthropic influences. The status of this community will 

be reviewed in the light of investigations at present in train in the central Northern 

Guinea areas of Nigeria. At the present state of our knowledge 'Isoberlinia Woodland' 

does not appear to occur in our area with the possible exception of the Longuda 

Upland (Land System IVa2). 

Of similar climatic distribution to (l). Although associated with rocky and other 

lithosolic sites, this community is primarily distributed on local colluvial soils in 

these areas with good profile depth and improved water relations due to the impedence 

of percolation by the underlying material. 

Species list Traverse from Uba to Mubi showing anthropic influences (Table 14, Column 3). 

Traverse near Little Gombi showing anthropic influences (Table 14, Column 4). 

128

SPECIES LIST Table 14 

Community Number Community Number 

Common trees & shrubs 

Balanites aegyptiaca 

Sterculla setlgera. 

Anogelssus leloearpus 

Lannea schlmperl 

Bombax costatum 

Prosopls afrlcana 

Pterocarpus erlnaceous 

Sclerocarya blrrea 

Entada afrlcana 

Combretum molie 

C. ghasalense _ 

C. glutlnosum _ 

Gulera senegalensls 

Zlziphus maurltlana 

PUlostlgma retlculatum 

Cassia singueana 

Annona senegalensls 

Grewla mollis _ 

Gardenia spp. _ 

Xlmenla amerlcana 

Maytenus senegalensls 

Commiphora afrlcana 

C. pedunculata 

Zlslphus mueronata 

Common trees & shrubs MAR > 750 mm (30 In) 

Steganotaenla arallacea 

Stereospermura kunthlanum 

Securldaca longepedunculata 

Kezalobus monopetalus 

Termlnalla brownll. 

Hannoa undulata 

Heerla Ins Ignis 

Trlchllla roka 

Vitex slmpllclfolla 

Adenodollchos panlculatus 

Swartzla madagascarlensls 

Hymenocardla aclda— 

Pteleopsls suberosa 

Grewla vlllosa 

Pavetta sp. -— 

Ochna schwelnfurthiana 

cussonla barterl 

Amblygonocarpus andongensls 

Parlnarl curatelllfolli 

P. polyandra 

Combretum blnderlanum 

C. hypopilinuTi 

C. nigricans var. elllotll • 

Termlnalla avicennlold'es 

T, laxlflora S— —- 

Plllostlgma thonnlngll 

locally common or rare trees and shrubs 

MAR 500- 1 OOP mm (20 - iiO In) 

Dalbergla melanoxylon 

Cassia sleberlana 

Cassia arereh 

Randla nllotica 

AlblEla chevallerl 

Lonchocarpus sp. — 

Maerua angolensls 

Boscla sallclfolla 

Common trees & shrubs MAR < 500 ran (20 lp) 

Acacia raddlana 

A. Senegal 

A. nllotica var. nllotica 

Cordla rothll 

Salvadora perslca 

Leptadenla pyrotechnlca— 

Maerua crass 1 folia 

Bauhlnla rufescens — 

Commiphora quadrlclncta 

Calotropls procera 

Cadaba farlnosa 

Hypheane thebalca 

Common species on llthosols 

Boswellla dalzlelll 

Detarlum mlcrocarpum 

Afrormosla laxlflora 

Strychnos splnosa — . 

S. lnnocua 

Brldella ferruglnea 

Crossopteryx febrlruga 

•I 

Common species on llthosols HAR>90Cfln (30 Inj 

Acacia dudgeonl . 

Burkea afrlcana . 

Acacia hock 11 . . 

Afzella afrlcana . 

Isoberllnia doka . 

1. dalzlelll . 

Monotes kerst lngll . 

Haematostaphls barterl . 

Species on heavy solfrg 

Feretla apondanthera 

Combretum aculeatum .. 

Securlnega vlrosa 

Capparls spp. 

Acacia ataxacantha^_ 

Dlchrostachys glomerata 

Grewla flavescens 

G, laslodlscus . 

Clssus quadrangularIs . 

Pseudocedrela kotschyl , 

Nauclea latlfolla 

Lannea humllls 

Acacia seyal . 

A. pOlyacantha/campylacantha 

A. slebenana 

MItragyna inermls n 

129 

Trees of farmland and fallow 

Adansonla dlgltata. 

Acacia alb Ida 

A. arablca var. adansonll 

Tamarlndus lndlca 

Dlospyros mesplllformls 

Flcus spp. . 

Borassus aethloplcura 

Butyrospermum paradoxum 

Vltex donlana - 

Park la clappertonlana 

Danlellla ollverl 

Khaya senegalensls. 

Riverain species 

Tetracers alnlfolla — 

Syzyglum gulneense— — 

Pteleopsls habeensls — 

Termlnalla macroptera — 

Alchornea cordlfolla — 

Kacaranga schwelnfurthll 

Mimosa plgra — — 

MUlettla thonnlngll — 

Irvlngla anlthll — 

-Ttebergla senegalensls — 

Paulllnla plnnata — 

Malacantha alnlfolla — 

MItragyna clllata — 

Klgella afrlcana —. — 

Raphla sudanlca — — 

Elaels gulneensls — 

Pandanus candelabrum — 

Garclnla oval1 folia — 

Salix ledermann11 — 

Celtls lntegrlfolla — 

Rare species 

Croton zambeslcus _ 

Gardenia sokotensls _ 

Acacia hebecladoldes _ 

Holarrhena florlbunda _ 

Uvarla chamae — 

Ormocarpum sp. _ 

Erythrlna senegalenls ._ 

Opllla celtldlfolla _ 

Capparls corymbosa— _ 

Carlssa edulls _ 

Fadogla spp. —. — 

Allophylus afrlcanus _ 

Antldesma venosum ,— _ 

Psorospermum febrlfugum_ 

Termlnalla glaucescens _ 

Leptadenla arborea — 

Addendum 

Boscla senegalensls. 

Tecrapleura sp. _*_ 

Securlnega »Irosa . 

Lannea sp.

4 TERMINALIA spp./COMBRETUM spp. SHRUB SAVANNA 

Physiognomy A low shrubland or fallow regrowth. There are scattered emergent trees. 

Dominant 

floristics 

Environmental 

relationships 

Typically Terminalia avicennioides and T. laxiflora CO-dominant with 

Combretum glutinosum, C. binderianum, C. ghasalense and sometimes C. hypopilinum. 

In the southeast sector 7". brownii is a common record while in the southwest, 

particularly in the wetter areas about the Lamurde anticline, Pteliopaia auberosa 

is a conspicuous constituent of the shrubland. 

Emergent trees are those typical of Community 1 together with 'economic* species 

typical of farmland such as Parkia, Tamarindus , Vitex doniana, Ficus spp. and 

Butyroapermum. in cultivated areas in the Wawa Bush, Terminalia spp. are common 

in the regrowth but, as the Combretum spp. so predominate, this intermediate area 

has been mapped as Combretum shrub Savanna (Community 12). 

An anthropic derivative of Community 1, occurring under Northern Guinea or near 

Northern Guinea conditions. 

Species list Based on traverses in the eastern Basement Land Province, the Gombi Plain and the 

Zomba Plain, Land Systems Ibl and Ib6. (Table 15, Column 1). 

Based on a traverse in the Lamurde Pediplain, Land System IIb2 (Table 15, 

Column 2). 

5 TERMINALIA spp. /COMBRETUM spp. SHRUB SAVANNA - ISOBERLINIA VARIANT 

Physiognomy A low shrubland or fallow regrowth. There are scattered emergent trees. 

Dominant 

floristics 

Environmental 

relationships 

Similar to (4) but with a conspicuous regrowth of Iaoberlinia spp. sometimes 

forming uniform, nearly pure stands. 

This community is probably best considered as an anthropic derivative of 

Community 3, occurring under similar climatic and edaphic conditions. It is to 

be found in the eastern Basement Land Province and on the Biu Upland, Land 

System IVal. 

Species list Traverse from Uba to Mubi (Table 15, Column 3). 

Based on records taken in the Little Gombi and Biu areas (Table 15, Column 4). 

130

SPECIES LIST Tabl 15 

Community 


Balanites aegyptlaca 

sterculla setlgera 

Anogelssus lelocarpus 





Scleroearya blrrea 

Number 

— 

— 

. 

. 

. 

. 

. 

. 

. 

. • 

Community Number 

Comnon species on llthosols HAR>90Omn (30 In) 

Acacia dudgeonl . 

Burkea afrlcana 

Acacia hockII 

Afzelta afrlcana 

Isoberllnla doka -— 

I. dalzlelll 

Monotes kerstlngll 

Haematostaphls barterl —- 

Entada afrlcana .— — . 

Combretum molle — - 

Species on heavy soils 

C, ghasalense — . 

C. glutlnosum — . 


Gulera senegalensls — . 

Combretum aculeatum . 

Zlzlphus maurltlana . 


Plllostlgma retlculatum . 

Capparls spp. 

Cassia slngueana 


. 

. 

Acacia ataxacantha 


Grewla mollis —. — . 

Grewla flavoscens 

Gardenia spp. - 

G. las lod 1 scus 

Xlmenla americana - 

Maytenus senegalensls . 

Commiphora afrlcana — 

C. pedunculata — 

Zlzlphus tnucronata .— — . 

Common trees & shrubs MAR > 750 run (30 In) 

Steganotaenla arallacea . 

Clssus quadrangular Is 

Pseudocedrela kotschyl 

Nauclea latlfolla 


Acacia seyal 


A. sleberiana 

Mltragyna lnermls 

_ 

S 

s 

s: s B 

Stereospermum kunthlanum 


. . 


Hexalobus monopetalus 

Termlnalla brownll 

Hannoa undulata —. 

Heerla Inslgnls 

Trlchllla roka — 

Vltex slmpllclfolla 


Swartzla madagascarlensls 

Hymenocardla aclda — 


GrewJa vlllosa — — 

Pavetta sp. — 

Ochna schweinfurthlana 

— 

— 

— 

— 

—— 

. 

- 

. 

. 

. 

. 

Adansonla dlgltata 

Acacia alb Ida . 

A. arablca var. adansonli 

Tamarlndus Indies 

Olospyros mesplllformls 

Flcus spp. 

Borassus aethioplcum 


Vltex doniana -— 

Park la clappertoniana 

Danlellla ollveri 

Khaya senegalensls — 

. _ 

— 

Cussonla barterl 

Amblygonocarpus andongensls —- . 


Parlnarl curatelllfolla 

P. polyandra 


C, hypopiUntil) —- 

C, nigricans var. elllotll 

Termlnalla avlcennlQldes 

T. laxlflora — 

Plllostlgma thonnlngll 

— 

— 

. 

• 

— 

Tetracers alnlfolla 

Syzyglum guineense— 

Pteleopsls habeensls 

Termlnalla macroptera 

Alchornea cord 1 folia — 

Macaranga schwelnfurthll 

Mimosa plgra — 

Mlllettia thonnlngll 

— 

— 

— 

— 

— 

— 

— 

locally common or rare trees and shrubs 

MAR 500- 1 OOP mm (20 - /jO In) 

Irvlngia smlthll 

.êbergla senegalensls 

Paulllnla pinnata 

— 



cassia arereh 

Randla nllotica . 

AlbIzla chevallerl . 

Lonchocarpus sp. 

rlaerua angolensls — 


— 

— 

ft 

Malacantha alnlfolla 

Mltragyna clllata — 

Klgella afrlcana 

Raphla sudanlca — 

Elaels guineensls 

Pandanus candelabrum 

Garclnla ovallfolla 

Salix ledermannll — 

Celtls integrlfolla 

— 

—— 

•— — 

—- 

— 

— 

— 

Common trees & shrubs MAR < SOP mm (20 In) 


A, Senegal . 

A, nllotica var. nllotica . 

cordla rothll . 

Salvadora pers lea 


Maerua crass I folia 

Bauhlnla rufescens - 

Commiphora quadrlclncta 

Calotropls procera 

Cadaba farlnosa 

Hypheane thebalca — 


Boswellla dalzlelll . . 



Strychnos splnosa 

S. lnnocua 

Brldella ferruglnea . 

Crossopteryx febriruga 

HI 

131 

Rare species 

Croton zambeslcus — — 

Gardenia sokotensls — — 

Acacia hebecladoldes — 

Holarrhena floribunda — — — 

Uvarla chamae — •— 

Ormocarpum sp. 

Erythrlna senegalenis 

Opilia celtidlfolla 

Capparls corymbosa— — 

Carlssa edulls — 

Fadogla spp, 

Allophylus africanus 

Antldesma venosum 

Psorospermum febrlfugum — 

Termlnalla glaucescens — 

Leptadenla arborea 

Addendum 

Boscla seneRalensls— — — — — — 

Tetrapleura sp. — — — — — — 

Securlnega »Irosa _;_ 

Lannea sp. _• — 

s

6 ACACIA HOCKII TREE AND SHRUB SAVANNA 

Physiognomy Low, widely spaced trees standing to 3-5 m (10- 16 ft) with scattered shrubs. 

Dominant 

floristics 

Environmental 

relationships 

The distinctive species in this community are A. hockii, Entada and Paeudocedrela 

in association with Combretum glutinoaum, C. ghaaalense and Ziziphua mauritiana. 

This community is confined in our area to basalt-derived heavy clay soils on the 

high lava plateaux. It is rarely free of some level of anthropic impact and occurs 

under near to full Northern Guinea conditions. It bears some similarities to the 

Acacia aeyal/Pseudocedrela community described by Clayton (1955) on heavy clays 

in the Shendam-Bashar area immediately to the west of the project area. As also 

described under Community 14, there is a tendency for A. hockii to replace other 

Acacia spp. on soils derived from basaltic materials. 

Species list Based on 0.2 ha (0.5 ac) plots and traverse records on the Biu Upland, Land 

System IVal (Table 16, Column 1). 

7 PARKIA PARKLAND 

Physiognomy A low farmland fallow with scattered regrowth of persistent shrubs and occasional 

widely spaced trees, usually of some economic value. 

Dominant 

floristics 

Environmental 

relationships 

Species list None. 

The herbaceous cover is described in part in Volume 4. The regrowth shrubs are 

those typical of Communities 4, 5, and 12. Typical trees are Parkia, Vitex, 

Butyroapermum, Daniellia, Khaya and Ficua spp. 

Long-standing, usually intense cultivation in the Northern Guinea and Sub-Sudan 

Zones. 

8 ANOGEISSUS/COMBRETUM spp. WOODLAND/TREE SAVANNA 

Physiognomy Variable from a low open woodland of the order of 3-6 m (10-20 ft) high to one 

containing a high proportion of dense, tall shrubs. Occasional taller emergent 

trees occur, often in localised groups. The density of erect woody stems per 

unit area is higher in this community than any of the other woodlands/tree 

savannas in the project area. 

Dominant 

floristics 

Environmental 

relationships 

Fairly rich in species but with a clear dominance of Combretaceae. Anogeisaua 

and Combretum nigricans var. elliotii are the typical dominants With C. glutinoaum 

and Terminalia spp. often co-dominant. However, this community often intergrades 

into Communities 1-3 and a conspicuous proportion of leguminous trees results. 

Widely distributed in the Sub-Sudan areas of the Gongola Valley and in the Wawa 

Bush on free-draining sites. It is possible that this community has arisen from 

past anthropic influences on the Afrormoaia/Detarium woodlands to which it may be 

slowly reverting. It would certainly appear to occur on the climatic boundary 

between the leguminous woodlands of the Northern Guinea Zone and the Anogeiaaus 

Woodlands of the Sudan Zone. It probably is most typically seen on the very 

free-draining soils in the Wawa Bush. 

Species list Based on 0.2 ha (0.5 ac) plots and traverses in the Wawa Bush, Land Systems 

Illbl and IIIb2 (Table 16, Column 2). 

. Based on 0.2 ha (0.5 ac) plots in the Gombe Hills, Land System IIc3 (Table 16, 

Column 3). 

Based on typical 0.2 ha (0.5 ac) plots on the sandstone plains of the Gongola 

Valley, Land Systems Ilbl, 2, 3 and 4 (Table 16, Column 4). 

132


Community Number 6 8 8 8 Community Number 6 8 8 8 

Common trees & shrubs COTx»n SDecïes on llthosols MAR>90Cnn ^jSO In^ 

Zlzlphus maurltlana — — W 

Pillostigma reticulatum — U- 

Cassla slngueana — L 

Annona senegalensis B 

Grewla mollis— — — — WL. 

Maytenus senegalensis — — II 

Common trees & shrubs MAR > 750 mm (30 fn) 

• ^ I 

-t- T t-T 

TB t-Jt- 

--T ~£- 

Um*»:. „fr-Irana ^^^TBT ^J ^ ^ 

Anarln hnrt.ll • 11 ^ N TW WW 

Af7»lla Jifrlrana • ! |\ | 

I, rtalilolll J J 

. pedes op heavy so 1; 

Grpwla fl.ivoRrpns 

.jr._ • • • • 

V1f.i»r nlmpllrlfnlln \ ^ " " " 

JL 

Swartzla madagascarlensls -- c::: _ 

-4-- • t-T- 

--ff--•: --ff--•: 

Swartzla madagascarlensls -- • —jt. 

Termlnalla avlcennloldes -— •• 

Locally common or rare trees and shrubs 

MAR 500. 1 000 mm (20 - IjO ini 

n 

1 

DAlhprgla mplftrmxylnn 1 ...s_._ i.._i _ 

Common trees & shrubs MAR < 500 mm, (20 JnJ 

Aeada rorldlanA 

. -S 

^:: s : 

V 

--I - :::3t: i 1 

..::&- 

::nr~ • i 

133 


Rare species 

flpllln «»lr.Hlffllln 

p^dogf« "»PP. 

Addendum 

1 1 1 1 1

9 ANOGEISSUS/DETARIUM SAVANNA WOODLAND/TREE SAVANNA 

Phys iognomy A low woodland at full development with emergent trees standing 10-13 m 

(33-43 ft) high. A well developed understorey of shrubs. 

Dominant 

floristics 

Environmental 

relationships 

This community contains many elements of Community 19, Anogeissus Woodland, and 

can be regarded as a mosaic of this with an impoverished northern form of the 

Afrormosia/Detarium - Detarium variant Community. In the latter, Detarium, 

Crossopteryx and Strychnoa spinosa dominate with a well developed shrub stratum 

Of Combretum glutinosum and Guiera. 

A Sub-Sudan climatic intergrade community on lithosolic sites. It covers the 

transition on such sites from Community 2 to Community 14. Its largest extension 

occurs on the ironstone outcrops over Kerri Kerri Sandstone in Land Systems Illbl 

and 2 and on the northerly parts of the eastern Basement Land Province in Land 

Systems Ib2 4 and 5. 

Species list Based on 0.04 ha (0.1 ac) plots in Land Systems Illbl and 2. (Table 17, Column 1). 

10 ACACIA SEYAL/A. POLYACANTHA SAVANNA WOODLAND/TREE SAVANNA 

Physiognomy Spreading trees, usually scattered but at full development sometimes forming a 

closed canopy. Typical height about 5 m (16 ft) with occasional taller trees 

standing to 8-9 m (26-30 ft). 

Dominant 

floristics 

Environmental 

relationships 

This community is very similar to Community 17 which is described in more detail. 

It differs in the more conspicuous proportion of A. polyacantha subsp. 

campylacantha and the greater prominence Of Mitragyna inermis and Entada. 

Confined to the Sub-Sudan Zone in the project area. It is probably best 

considered as a 'wetter' variant of Community 17 occurring on heavy clays under 

higher rainfall and also where the density of the drainage network exerts a 

riparian influence. It occupies sizable areas on the Giwano Plain, Land System 

IIa6, where it forms a mosaic with the Sorghum grassland of Community 13. Elsewhere 

it usually occupies discrete low-lying areas distributed among the 

Anogeissus/Acacia seyal Savanna Woodlands, Community 16. 

Species list Based on 0.2 ha (0.5 ac) plots in the Deba Habe area of the Wagur Plains, Land 

System IId4 (Table 17, Column 2). 

11 ACACIA DUDGEONII/COMBRETUM GLUTINOSUM TREE AND SHRUB SAVANNA 

Physiognomy A low shrubland with emergent trees standing to 5 m (15 ft) either scattered or 

in localised clumps. 

Dominant 

floristics 

Environmental 

relationships 

The species composition is similar to Community 14 with the additional presence 

Of such typical fallow species as Pilioatigma, Entada, Maytenus and Terminalia 

laxiflora. 

An anthropic derivative of Cummunity 14, occurring in the Sub-Sudan Zone on 

lithosolic and thin-soil sites generally. It is particularly conspicuous in 

the densely populated areas on rocks of the Basement Complex. 

Species list Based on 0.2 ha (0.5 ac) plots in the Wandali area of the Whada Plain, Land 

System Ia2 (Table 17, Column 3). 

Traverse on the Gongola Hills, Land System Ic5, near Kaltungo (Table 17, Column 4). 

134


Community Number 10 11 11 Communitv Number 10 11 


Balanites aegyptlaca 

Sterculla setlgera 



Bombax cos tatum 





Combreturo mo lie 

C. ghasalense _ 

C, glutlnosum _ 


Zlzlphus maurltiana 

Plllostlgma retlculatum 



Grewla mollis _ 

Gardenia spp. _ 

Xlraenla amerlcana 

(laytenus senegalensls 

Commiphora afrlcana- 


Zlzlphus mucronata. 





Hexalobus monopetalus . 

Terminal la brownll — 


Heerla Ins Ignis — —. 

Trlchllla roka — — 

vitex slmpllclfolla 

Adenodollchos panlculatus — 

Swartzla madagascarlensls —- 


Pteleopsls suberosa —- — 

Grewla vlllosa — — — 

Pavetta sp. — — — — 

Ochna schwelnfurthlana 

Cussonla barterl .— 


Parlnarl curatellirolla —- — 

P. polyandra - 


C. hypopilinum 

C. nigricans var. elllotll — 

Termlnalla avlcennloldes -— 

T. lax 1 flora — — 

Plllostlgma thonnlngll — 


MAR 500- 1 000 mm (20 - 1;0 In) 

Dalbergla melanoxylon . 

Cassia sleberlana — 

Cassia arereh 

Randla nllotica 

Alblzla chevallerl 

Lonchocarpus sp. — 

Maerua angolensls — 

Boscla sallelfolla — 

Common trees & shrubs MAR < 500 mm (20 in) 

Acacia raddlana _ 

A. Senegal _ 

A. nllotica var. nllotli 

Cordlarothll _ 

Salvadora perslca _ 

Leptadenla pyrotechntca- 

Maerua crass 1 folia _ 

Bauhlnla rufescens _ 

Commiphora quadrlclncta— 

Calotropls procera _ 

Cadaba farlnosa _ 

Hypheane thebalca _ 


Boswel11a dalzlelll 

Detarlum mlcrocarpura 


Strychnos splnosa — . 

S. lnnocua — . 


Crossopteryx febrlruga. . 

[ 

I 

s 

•I 

hL. 

135 

Common species on llthosols MAR>900mm (30 In) 

Acacia dudgeon! 

Burtcea afrlcana . ,, . 

Acacia hock 11 

Afzella afrlcana 

Isoberllnla doka 

1. dalzlelll 

rlonotes kerstlngll . 

Haematostaphls barterl 

Speeres on heavy soils 


Combretum aculeatum 


Capparls spp. 

Acacia ataxacantha__ . . 


Grewla flavescens 

G. laslodlscus t 

CIssus quadrangular Is 

Pseudocedrela kotschyl ; 

Haue lea lat 1 rol la 


Acacia seyal 


A. sleberiana 

Mltragyna Inermls 


Adansonla dlgltata 

Acacia alb Ida . __ 


Tamarlndus indlca __ 


Flcus spp. — 

Borassus aethloplcum 

Butyrospermum paradorum 

Vltex donlana — 

Parkla clappertonlana 

Danlellla ollverl 

Khaya senegalensls — — 


Tetracers alnlfolla — 

Syzyglum gulneense— — — — — 

Pteleopsls habeensls — — — 


Alchornea cordlfolla 

Macaranga schwelnfurthll 

Mimosa plgra —- 

Mlllettla thonnlngll 

Irvlngla smlthll 

.Ttebergla senegalensls — — — — 

Paulllnla plnnata 

Malacantha alnlfolla 

Mltragyna clllata — — — — 

Klgella afrlcana 

Raphla sudanlca — — 

Elaels gu ineens Is — 


Garclnla ovallfolla — — — — 

Salix ledermannll — 

Celtls Integrlfolla — — — 

Rare species 

Croton zambeslcus — 

Gardenia sokotensls — — . — 

Acacia hebecladoldes — — 

Holarrhena florlbunda — 

Uvarla chamae — —- — — 


Erythrlna senegalenls -— 

Opllla celtldlfolla 

Capparls corymbosa— —- 

Carlssa edulls ___ - 

Fadogla spp. 

Allophylus afrlcanus 

Antldesma venosum .. _ 

Psorospermum febrlfugura 

Termlnalla glaucescens — 


Addendum 

Boscla senegalensls — — — 

Tetrapleura sp. -_ — — 


Lannea sp. 

s: 

£ ÏÏM 

:s: 

u 

_*_

12 COMBRETUM spp. SHRUB SAVANNA 

Physiognomy An open to dense low shrubland with occasional emergent trees. 

Dominant 

floristics 

This community spans a range of shrublands dominated by species of Combretum. 

In the Wawa Bush and on sandy soils in the southwest of the project area C. nigricans 

var. elliotii and to a lesser extent C. binderianum tend to dominate. To the east 

and north, C. glutinosum and C. ghasalense are more conspicuous. 

Environmental 

relationships 

This community is best considered as a plastic anthropically derived shrubland 

distributed largely in the Sub-Sudan Zone and the higher rainfall sector of the Sudan 

Zone. It forms a transition between the rernunaiia-dominated shrublands of the 

Northern Guinea Zone and the Guiera-dominated ones of the Sudan Zone. This transition 

is reflected in the changing proportions of associated species and such species 

as Terminalia laxi flora are replaced by such Sudan elements as Guiera, Annona, Cassia 

singueana and Ziziphus, as drier conditions prevail. 

Species list Based on 0.2 ha (0.5 ac) plots near Dukku in Land System Illbl (Table 18, Column 1). 

Based on 0.2 ha (0.5 ac) plots in Land System IIIb2 (Table 18, Column 2). 

13 SORGHUM ARUNDINACEUM GRASSLAND 

Physiognomy A tall floodplain grassland standing to 5 m (16 ft) high. 

Dominant 

floristics 

Environmental * 

relationships 


Virtually a pure continuous stand of S. arundinaceum. 

The southern equivalent of Community 30. These grasslands are subject to intense 

burning and are probably a fire-induced disclimax of Communities 10 and 17, occurring 

on vertic clays in the Sub-Sudan Zone. However, further study is needed and such 

factors as duration of flooding could also affect the distribution of this community. 

14 BOSWELLIA/ACACIA spp. SAVANNA WOODLAND/TREE SAVANNA 

Physiognomy Scattered trees, sometimes with more dense local groupings, standing to 7-9 m 

(23-30 ft) with typically a well developed ground cover of shrubs beneath. 

Dominant 

floristics 

Environmental 

relationships 

This community is characterised by the dominant presence of Boswellia, Acacia 

dudgeonii or A. hockii and Combretum glutinosum. 

This community replaces Communities 2 and 9 either under more dry Sudan climatic 

conditions or under markedly adverse edaphic conditions, steep slope, very stony 

shallow soils in the Sub-Sudan Zone. Elements of the leguminous woodland are 

typically present but these disappear under increasing Sudan conditions, and this 

community grades into Community 21. A. hockii tends to replace A. dudgeonii on 

basalt-derived soils and in the southeast of the project area. 

Species list Based on 0.2 ha (0.5 ac) plots in the middle Gongola Valley on Basement and Bima 

Sandstone-derived soils (Table 18, Column 3). 

Based on 0.2 ha (0.5 ac) plots on basalt soils in the Biu Hills, Land System IVcl 

(Table 18, Column 4). 

A traverse across Basement and Bima Sandstone units in the area of Song, Land 

Systems IIa7, Id7 and Ic3 (Table 19, Column 1). 

15 HAEMATOSTAPHIS/BOMBAX WOODLAND/TREE SAVANNA 

Physiognomy Localised stands of tall woodland with emergents reaching as high as 30 m (100 ft). 

Dominant 

floristics 

Environmental 

relationships 


A specialised community characterised by the presence of H. barteri and B. costatum 

associated with a group of species more typical of riparian and parkland vegetation, 

Diospyros mespiliformis, Ficus spp., Adansonia digitata and Vitex donniana. 

Pterocarpus erinaceous is common. 

The so-called 'Inselberg Community'. In the project area typical of deeper soils 

and colluvial pockets associated with rock clefts on the hills of the Basement 

Complex but also occurring on similar sites on the Bima Sandstone. Typically found 

scattered among the thin-soil communities* of the Sub-Sudan and Northern Guinea 

Zones. A symbol is employed on Map 4 to indicate areas where it is particularly 

conspicuous. 

136




Balanites aegyptiaca 

Sterculla setlgera 








Combretum molle 

c. ghasalense _ 

C. glutInosum _ 


Zlzlphus maurltlana 

Plllostlgma retlculatum— 



Crewla mollis _ 

Gardenia spp. - 

Xlmenla amerlcana 

Maytenus senegalensls 

Commiphora afrlcana 


Zlzlphus mucronata 





Hexalobus monopetalus 

Termlnalla brovmll 


Heerla Inslgnls 

Trlchllla roka 

Vltex slmpllclfolla 


Swartzia madagascarlensls 



Grewla vlllosa — 

Pavetta sp. 

Ochna schwelnfurthiana 

Cussonla barterl 


Parlnarl curatelllfolla 

P; polyandra 


C. hypopillnuTj 

C. nigricans var. ell lotll 

Termlnalla avlcennloldes 

T. laxlflora 

Plllostlgma thonnlngll — 


HAR 500- 1 000 mm (20 - UP In) 



Cassia arereh 

Randla nllotlea 

Alblzla chevalleri 

Lonchocarpus sp. 

Haerua angolensls 


Common trees & shrubs MAR < 500 mm (20 Inj 


A, senega! — 

A. nllotlca var. nllotlc 

Cordla rothll 

Salvadora pers lea 


Maerua crass 1 folia 

Bauhinla rufescens — 

Commiphora quadrlclncta— 

Calotropls procera — 

Cadaba farlnosa — 

Hypheane thebalca — 


Boswel Ha dalzlelll 



Strychnos splnosa 

S. lnnocua 


Crossopteryx febriniga 

137 

Comnon species on llthosols MAR>9O0nn (30 In) 

Acacia dudgeonl . _ 

Burkea afrlcana , „ 

Acacia hockl! '. . 

Afzella afrlcana . 

Isoberllnla doka _ 

I. dalzlelll . . 

Honotes kerst lngll . . 

Haematostaphls barterl . 

Feretla apondanthera _ 

Combretum aeuleatum . 

Securlnega vlrosa . 

Capparls spp. . 

Acacia ataxacantha . _ 


Grewla flavoscens . 

G. laslodlscus . . 

Clssus quadrangularls _ 

Pseudocedrflla kotschyl , 

Nauclea lat 1 folia _ 

Lannea humllis _ 

Acacia seyal . 

A. pOlyacantha/campylacantha. 

A. sleberiana - 

Mltragyna Inermls - 


Adansonla dlgltata . 

Acacia alblda _ 


Tamarlndus lndlca ' . 


Flcus spp. - 

Borassus aethloplcum . 


Vltex doniana — - 

Park la clappertoniana , 

Danlellia ollveri - 

Khaya senegalensls — . 


Tetracers alnlfolia - 

Syzyglum gulneense - 

Pteleopsls habeensls . 

Termlnalla macroptera - 

Alchornea cord 1 folia — - 

Macaranga schweinfurthll 

Hlmosa plgra - 

Mlllettla thonnlngll • 

Irvlngla smlthll - 

•Tcebergla senegalensls - 

Paullinla plnnata - 

Malacantha alnlfolia . 

Mltragyna clllata — - 

Klgella afrlcana - 

Raphla sudanlca • 

Elaels gulneensls - 

Pandanus candelabrum - 

Garclnla ovallfolla 

Salix ledermann 11 • 

Celtls lntegrlfolla • 

Rare species 

Croton zambeslcus — . 

Gardenia sokotensls . 

Acacia hebecladoides . 

Holarrhena florlbunda . 

Uvarla chamae - 


Erythrlna senegalenls 

Opllta celtldlfolla . 

Capparls corymbosa— 

Carlssa edulls — - 

Fadogla spp. - 

Allophylus afrlcanus , 

Antldesma venosum . 

Psoro spermum febrlfu 

Termlnalla glaucescens 


Addendun 

Boscla senegalensls— 

Tetrapleura sp. — 

Securlnega rirosa 

Lannea sp. — 

SI 

;: 

:!: 1

16 ANOGEISSÜS/ACACIA SEYAL SAVANNA WOODLAND/TREE SAVANNA 

Physiognomy Typically an open conformation with scattered trees, fairly widely spaced but with 

local denser stands. The emergents stand to 10-13 m (30-43 ft) with an understorey 

of scattered shrubs. 

Dominant 

floristics 

Environmental 

relationships 

The species composition is very variable, containing the major elements of 

Communities 10, 17, 19 and 20. In the more northerly distribution of this 

community A. seyal is particularly conspicuous while to the south and the southeast 

A. polycantha, A. hockii and occasionally .4. hebecladoides assume more importance. 

In parts of the southern areas, the tall grass growth leads to fierce annual fires. 

Here the shrub growth is depressed and scattered trees of Anogeissus, Sterculia and 

Entada are a feature. 

An edaphic intergrade between Communities 10, 17, 19 and 20, found either on intermediate 

clay/loam soils or where a rapid alternation of the two soil types occurs. 

Species list Based on 0.2 ha (0.5 ac) plots in the northern part of the Wagur Plains, Land 

System IId4 (Table 19, Column 2). 

Based on 0.2 ha (0.5 ac) plots in the Deba Habe - Talasse area of the Wagur Plains, 

Land System IId4 (Table 19, Column 3). 

A traverse from Yola to Song primarily on colluvial and alluvial areas (Table 19, 

Column 4). 

17 ACACIA SEYAL SAVANNA WOODLAND/TREE SAVANNA 

Physiognomy Spreading trees, usually scattered but at full development forming a closed canopy. 

Typical height about 5 nu(16 ft). 

Dominant 

floristics 

Environmental 

relationships 

On certain fully vertisolic clays this community can be found comprising a pure stand 

of A. seyal, with virtually no shrub growth, only a broad expanse of low grass cover 

beneath the trees. The concept of this community has however been expanded to 

include the association with a group of typical species like Anogeissus, Combretwn 

ghasalense, C. aculeatum, Balanites, Bombax and Ziziphus. 

Probably best considered as the climax community on vertic clays, primarily in the 

Sudan Zone but also capable of occurring under Sahel conditions. In the Sub-Sudan it 

gives way to Community 10 and, under wetter conditions, to an association with 

Pseudocedreia. under hydromorphic and halomorphic soil conditions it is replaced by 

Communities 27 and 28. Large expanses of this community occur on the Wagur Plains, 

Land System IId4, but more typically it forms a mosaic with Community 16. 

Species list Based on 0.2 ha (0.5 ac) plots in the Wagur Plains, Land System IId4 (Table 20, 

Column 1). 

18 COMBRETUM spp. /ACACIA spp. SHRUB SAVANNA 

Physiognomy Low shrubland with emergent trees. 

Dominant 

floristics 

Environmental 

relationships 

Of similar species composition to Community 16, with greater prominence of the 

shrubby regrowth component. 

The anthropic derivative of Community 16. Fallow regrowth and regenerating 

shrubland. 

Species list Traverse in the Bajiram Plain, Land System IId3 (Table 20, Column 2). 

138


Community Number 14 16 1

Conmon trees 4 shrub3 

Pr.orwrjr-pi«: ei-1nr»ppnii90qnn (30 In) 

J • • I rt0l7K.HI 

Combretum molle — H ^^•~^B J-Û— SDecles on heavy soils 

C. ghasalense — — — ^L. -^Bn-^| 

C. glutlnosum — — ^P~^Û~^P l - W l Feretla aDondanthera I ^ | J | M 

Û rmnhrof.iim amilo.nr.itm • ^ H ^ H ^ J 

Pillostlgma retlculatum — 

Annona senegalensis 

Maytenus senegalensis — — 

Harmlpa lntlfolln III l| 

Conmon trees & shrubs MAR > 7SO tun (30 in) 1, a1eh»i~i.-,nn \ • N 1 M 


Stereospennum kunthlanum 

Renirt'lacn long*>r 

.— — 

,,rt,, nc


Community Number 17 18 Community Number 17 18 

Common trees * shrubs Connon species on llthosols MAR>9QCttn (30 In) 

Srler-nrsrya MIT-OJI 1 ^ | 

slur 1nn«t«n ^ H PP^ 

innnnq ponPP«l»»n 750 mm (30 In) 


MAR 500- 1 000 mn (20 - iiO In) 

Dfllhprgla fnplannxylnn 1 1 

Connon trees & shrubs MAR < 500 mi (20 lp} 

Ar.nr.in rnHrtlnna 

Connon species on llthosols 

IN 1111 1 II I 

Boswellta dalzlelll _ J, 

140 

T, rtfll-rleHf 

Rlvsraln species 

Rare species 

Ormnrqrptim sp. 

npllln rolMrllfnl !n 

Par!

* 

IM*. 

tb.. 

i>v- ,' "1-- '«4. .' v 7 f * - 'Vi'•*&?•' 

*. ^ -VH V! ^•'^ .is 

PLATE 1/13 acacia seyal Tree Savanna on vertic clay flat. 

March 1967. 

PLATE 1/14 Land System Vel, the Arege Plain. Cordia rothii/ 

Acacia raddiana Tree and Shrub Savanna. Thickets 

of Salvadora persica can be seen. March 1967. 

141

19 ANOGEISSUS WOODLAND/TREE SAVANNA 

Physiognomy Typically an open woodland standing to 10-15 m (33-50 ft) high with no distinct 

strata but with emergent trees and a diffuse layer of smaller shrubs and trees. 

Dominant 

floristics 

Environmental 

relationships 

In its typical form this community is fairly rich in species. Trees such as the 

dominant Anogeissus with Bombax, Sclerocarya and numerous others form the upper 

canopy. In the lower levels Guiera and Combretum glutinosum are the major shrubs. 

A more northerly drier variant can be recognised where species such as Acacia 

Senegal, Commiphora spp. and Dalbergia become more conspicuous. 

The characteristic community of unfarmed areas in the Sudan Zone. Good examples 

are to be seen in the forest reserves of the Damaturu Plain, Land System Vc2. On 

shallow soils it intergrades with Communities 9 and 14. On heavier or more silty 

soils tending to hydromorphism there is an increasing tendency towards thicket 

formation. 

Species list 'Typical form'. Based on observations in forest reserves in the Damaturu Plain, 

Land System Vc2 (Table 21, Column 1). 

•Northern variant' . Based on observations in Land Systems Vc2 and 3 (Table 21, 

Column 2). 

"Moist variant'. Intergrading to Community 20. Based on observations in Land 

Systems Vc2 and 3 (Table 21, Column 3). 

20 ANOGEISSUS/ACACIA ATAXACANTHA WOODLAND/TREE SAVANNA* 

Physiognomy Similar to Community 19 but with a regular interspersed pattern of dense thickets. 

Dominant 

floristics 

Environmental 

relationships 

Similar to Community 19 but tending towards Community 16 in character. The major 

thicket species are Acacia ataxacantha, Capparis tomentosa, Cissus quadrangular is, 

Combretum aculeatum, Grewia flavescens, G. lasciodiscus, Securinega, Ziziphus 

mauritiana, Z. mucronata, Dichrostachys and Feretia. 

Occurs in the same climatic range as Community 19 on heavier soils tending to 

hydromorphism. As a mapping unit, it is shown as occurring in Land System Vc2 

where it occupies extensive tracts of land. Localised pockets do however occur 

throughout the Anogeissus Woodlands. 

Species list Traverse in Land System Vc2 (Table 21, Column 4). 

21 BOSWELLIA WOODLAND/TREE SAVANNA 

Physiognomy Occasionally an open woodland but more typically a tree savanna of scattered trees 

standing to about 10 m (30 ft) with limited shrub growth beneath. 

Dominant 

floristics 

Environmental 

relationships 


The floristics of this unit are not fully known for the project area although 

similar communities are described for Cameroon (Letouzey, 1968). It would appear 

to differ from Community 14 primarily in the greater predominance of Boswellia, 

which can sometimes occur in nearly pure stands, sterculia setigera is a common 

accompanying species, and accompanying shrubs are usually limited in number. 

Best considered as the typical community of lithosolic sites in the drier sector 

of the Sudan Zone, perhaps extending into the Sahel. It probably also occurs on 

extremely rocky sites under wetter climatic conditions. It is for example very 

common on volcanic plugs and has been mapped as occurring in the northern part of 

the Mandara Mountains, Land System Ic2- 

* Tangled thickets of similar species composition also occur in Communities 10, 16, 17, 27 and 28. 

142


Community Number 19 19 1 9 20 Community Number 19 19 19 20 

Common trees & shrubs Common species on llthosols MAR>900mn (30 InJ^ 

A re gels sus lelocarous ^^P^P'~fl 

Lannea schlmperl -— — — ^ 1 

Plllostlgna retlculatum —- — ^B~~Û~~W 

Common trees 4 shrubs MAR > 750 mm (30 In) 

An'blyeflnn''^rT l, is andonpensls 


MAR 500- 1 COO mm (20 - ^0 lrj2 

Dalbergla melanoxylon 11 J B l_l 

Cassia sleherlana 1 1 1 

Cassia arprPh U . 

Rnndla nllntir» 

Alhlr.tn rhpvallppi 

H Q 

T/inrhnrarpns RJ^ | | 

Comon trees & shrubs MAR < 500 mm (20 JpJ 


A. senepal 1 II 1 

Salvadora pers|r>a 


Boswellla dalzlftlll V 

• T, rtat7l\t>yi1 

1 BH Haematostaphls bartert 

H-^H-4-l Species on heavy soils 

H-^^H- npnnrtanfh« H^ • • • ^M 

- - - • ' • ' • ' 


Rare species 

nrmnrprrîm Sp, 

I • aaaenaun 

143 

npllla rPlMrtlfnllA 

SecurineRa »Irosa 

l.ann»a sp. 

—i i • 

• M~ • •

22 ACACIA SENEGAL/COMBRETUM GLUTINOSUM TREE AND SHRUB SAVANNA 

Physiognomy A low open shrubland with emergent trees. When protected, as in some of the 

forest reserves, a dense tall shrubland/woodland up to 5 m (16 ft) in height 

can develop. 

Dominant 

floristics 

Environmental 

relationships 

The shrub component of this community is virtually identical with that of the 

shrub savannas described under Communities 23 and 24. It differs in possessing 

a high proportion of low tree growth, the characteristic species being A. Senegal, 

Commiphora pedunculate and usually Dalbergia. 

Considered to be an anthropic derivative of the more northerly Anogeissus Woodlands 

of the Sudan Zone. It is thought to be an intermediate impact level 

community, reverting to Anogeissus Woodland if protected and giving rise to 

Communities 23 and 24 under more intense utilisation. The available records in 

the project area come from the central sector of the Lantewa Dunefield but the 

known distribution of the gum-arabic producing areas indicates that this community 

occupies a considerable area of the sand plains and dunefields, as shown in Map 4. 

Species list Based on 0.04 ha (0.1 ac) plots south of Lantewa in Land System Vcl (Table 22, 

Column 1). 

23 GUIERA /COMBRETUM GLUTINOSUM SHRUB SAVANNA 

Physiognomy Variable, ranging from an open to dense cover and from low fallow regrowth to a 

near tree and shrub savanna up to 3 m (10 ft) in height. Occasional residual 

trees may occur. 

Dominant 

floristics 

Environmental 

relationships 

The species composition of this community remains remarkably homogeneous despite 

wide variation in site history. C. glutinoaum and Guiera as the co-dominants 

occupy by far the greater part of the arboreal cover. The remnant trees are 

usually Anogeissus, Sterculia or one of the other common Sudan Zone woodland 

species. In young fallows Ziziphus mauritiana and Cassia singueana are usually 

more conspicuous while, with increasing age, elements typical of the Anogeissus 

Woodlands increase in importance. 

The typical regrowth community of the central belt of the Sudan Zone. It is 

associated with a fairly high level of anthropic impact (see also comments under 

Community 29), distributed about the 750 mm (30 in) isohyet, and occurs as a 

climatic intergrade community between Communities 24 and 12. 

Species list Based on 0. 04 ha (0.1 ac) plots and traverses in the Damaturu/Goniri area, Land 

System Vc2 (Table 22, Column 2). 

24 GUIERA SHRUB SAVANNA 

Physiognomy An open shrub savanna with few emergent trees. Occasional more dense cover can 

be found where there is some degree of protection. 

Dominant 

floristics 

Environmental 

relationships 

Dominated by Guiera, not uncommonly found in near-pure stands. Associated species 

are variable but commonly include Ziziphus mauritiana, Comb re tum glutinosum, 

Piliostigma reticulatum, Boscia senegalensis and Calotropis procera. 

The typical regrowth community on free-draining soils in the northern Sudan Zone, 

impinging slightly into the Sahel Zone (see comments under Community 29). 

Species list Traverses in the Gulumba area. Land Systems Vil, ViS, and Vh2 (Table 22, Column 3). 

Traverses in the Gashua - Geidam area, Land Systems Vcl and Vfl (Table 22, Column 4). 

144


Community Number 2 2 23 24 24 Community Number 22 23 24 24. 

Common trees & shrubs Common species on llthosols MAR>900mn (30 In] 

Zlzlphus maurltlana — — y- 

Plllostlgma retlculatum 1- 

Cassla slngueana H- 

Comnon trees & shrubs MAR > 750 mm (30 In) 

s 

. 1. \ 

__LL 

_jr 

_jr 

C. nigricans var. elliotll -. 

Termlnalla avlcennloldes ff rnr 


MAR 500- 1 000 mm (20 - W> In) 

Dalbergla melanoxylon — — — II PU- 

• 

n 

\ 

_JL 

::i: s 

• 1 

1 1 

•• HI 

1 

ACAMA riiiri mnn 1 

niiHrpa afrfrana 

Af7.pl In afrtcana 

1, dalzlelll 

1 1 • 1 


Hnrnhrptim amilpnT.irm 


1 

1 

1 I • 

Capparls spp- 1 

Dlchrostachys glome rata 

Crewla flnvrsnpns ,. 

1 

1 • r Sil " 

Clssiis miadranpiilarls 

Pseudocedrela kotsehyl 

Hauelea lat1 folia 

3—0—0.1.- 

Lt 1pÉÉrp__ 

L l_ s W 

- - -. 

'II JÊ II 

Acacia spyal 


A. slPhprj.nna 

::ff: :":: 


TamarlnriiK 1 nH 1 r A 


Plcus spp. - 

Borassus aethloplcum 

Butyrospermum paradoxum . 

Vltex doniana — - 

Park la clappertonlana 

Danlellla Oliver* - 


, Tetracers alnlfolia 

• 

Syzyglum gulneense 


Macaranga schwelnfurthll — 

Mllletm thonnlngll 

Raphla sudanlca — 


Care In la oval 1 folia 


Rare species" 

AcaMn mrifllftna win .ZLT 

in i 

'~]*~ 

AcaMn mrifllftna win .ZLT 

k 

in i 

HnrrtPnta snVnr.on«!ts 

Ar.-iMa hPh*»M.iHn1rlP* 

Hnlarrhena flnr-lhunrtn 


'- AcaMn mrifllftna win k 

in i 





'- AcaMn mrifllftna win 

in i 





Boswellla dalzlelll 

1 

" --] •1 

1 

•1 

" lir' 

Jl 

" ••1 

"ITT H -\ 

I s 

145 

Erythrlna senegalenls — 

HplHfl pplMrtlfnlla 

Capparls corymbosa— 

Fadogla spp. 

Allnphylii«! afrlrnnii« 

AnMr1f>

25 ADANSONIA PARKLAND 

Physiognomy Farmland and farm fallow with widely spaced individual tree standing to as much as 

20-30 m (66-100 ft) at full maturity. Some low shrub regrowth. 

Dominant 

floristics 

Environmental 

relationships 


26 ACACIA ALBIDA PARKLAND 


those typical of Communities 23, 24 and 29. Adansonia digitate is the most common 

parkland tree with other economic and shade trees such as several Ficus spp. 

Remnant species from the original Anogeissus Woodlands do however occur. 

Typical of long-standing intensive cultivation in the Sudan Zone on free-draining 

soils. 

Physiognomy Farmland and farm fallow with widely spaced individual trees standing to 15 m (50 ft) 

in height. Restricted low shrub regrowth. 

Dominant 

floristics 

Environmental 

relationships 



those typical of Communities 24, 29 and occasionally 33. The trees are almost 

entirely Acacia albida. 

Typical of long-standing cultivation in the northern Sudan Zone but extending both 

into the Sahel Zone and drier areas of the more southerly Sudan Zone. 

27 ACACIA spp./BALANITES TREE AND SHRUB SAVANNA* 

Physiognomy Typically tree and shrub savanna sometimes developing into a savanna woodland. 

Dominant 

floristics 

Environmental 

relationships 

This unit is best considered as an ill defined grouping of communities. It is 

nevertheless a convenient mapping unit for an interrelated complex of plant 

associations characterised by the dominant presence of Balanites aegyptiaca and 

Acacia seyal. it differs from Community 17, which is essentially a tree savanna 

composed of either a pure stand of A. seyal or A. seyal with a limited proportion 

of accompanying species, in exhibiting a more heterogeneous species composition 

associated with a number of other Acacia spp. It includes for example the A. seyal 

and A. Senegal thicket in the interdune depressions of Land System Vh2 (Pullan, 

1969), the A. seyal and A. nilotica var.nilotica tree savanna of the cracking clay 

plains of the northeast (Higgins et al. i960) and the 'Acacia bushland and wooded 

grassland' described by Clayton (1957) in the Hadejia floodplain (see comments 

under Community 28). 

Found on heavy soils throughout the project area. In the Sub-Sudan Zone it tends to 

be replaced by Communities 17 and 10 on the vertic clays, but elsewhere it is 

distributed over the hydromorpnic, halomorphic and vertic soils. As halomorphism 

becomes pronounced it tends to give way to Community 28. 

Species list Traverse from Gashua to Geidam, Land Systems Vfl and Vg2 (Table 23, Column 2). 

Traverse near Gulumba, Land Systems Vil, Vi3 and Vh (Table 23, Column 3). 

Observations near Yobe river. Land System Vf3 (Table 23, Column 4). 

28 ACACIA spp./BALANITES/LANNEA HUMILIS TREE AND SHRUB SAVANNA* 

Physiognomy Typically tree and shrub savanna sometimes developing into savanna woodland. 

Dominant 

floristics 

Environmental 

relationships 

This unit is best considered as a variant of Community 27, characterised by the 

additional presence of conspicuous gregarious clumps of Lannea humilis. 

There is no clear division between the two communities but if L. humilis is present 

in significant proportion, then the vegetation should be classified under this 

heading. 

Found on heavy soils with a marked tendency to halomorphism throughout the Sudan 

and Sub-Sudan Zones in the project area. 

Species list Traverse near Gulumba, Land Systems Vil, Vi3 and Vh2 (Table 23, Column 1). 

* Thickets of Acacia ataxacantha and associated species are common in these units, often associated 

with termitaria. 

146



Common trees & shrubs Common species on llthosols MAR>900mn (30 In) 

ll_Hfl_ ACACIA dudReoni 

T, rtn1«t»11f 

_ - - - rnmhi-ofjim flMilnflT.llm H H HQ 

Zlzlphus raauritlana — — — ^P ~ff^ ~l ll_ll SpeurlnftRA vlrosa II M ^M 

Common trees & shrubs MAR > 750 pm (30 In) A, sUhPrmnn Ml IM • ! • 


MAR 500- 1 000 mm (20 - ifO in) 


CassiA sipfr»r1arvi 

Ranrlln nllotlcA 

Common trees & shrubs MAR < 500 mm (20 \f\) 

Acacia rarirttnna ^L | J | 

Sfllvarlnra ppr«ijf*fl 



Rare species 

• .Ormocarpum sp. 

[I Opilla ceir-frtimiffl 

147 

Addendum 

securineea Tirosa

29 ZIZIPHÜS/ACACIA spp. TREE AND SHRUB SAVANNA 

Physiogonomy Scattered shrubs and regenerating trees with occasional emergent residual trees. 

Dominant 

floristics 

Environmental 

relationships 

Essentially the same species composition as Communities 27 and 28 but with a far 

higher proportion Of Z- mauritiana. 

Degraded shrub community resulting from anthropic impact on Communities 27 and 28. 

However, it would appear that under particularly severe impact, this community can 

replace Communities 24 and even 23 on free-draining soils although it is normally 

considered a heavy-soil type. This feature is particularly conspicuous in the 

heavily populated, intensively farmed sand plain and dune areas in the alluvial 

complexes in the northwest of the project area, where the proximity to the hydromorphic 

regime may have some influence on the vegetation. In other areas this 

community is found on light soils overlying heavy soils. 

Species list Traverse near Gulumba, Land Systems Vil, Vi3, Vh2 (Table 24, Column 1). 

Derived from Clayton (1957) (Table 24, Column 2). 

30 SORGHUM AETHIOPICUM GRASSLAND 

Physiognomy Tall floodplain grassland standing to 5 m (16 ft) high. 

Dominant 

floristics 

Environmental 

relationships 


Virtually a pure stand of S. aethiopicum above a low ground cover of hydromorphic 

herbs and grasses. 

The northern equivalent of Community 13, occurring under similar conditions on the 

cracking clay plains about Lake Chad. 

31 ACACIA RADDIANA TREE AND SHRUB SAVANNA 

Physiognomy An open tree savanna with scattered trees standing to 12 m (40 ft) and with 

scattered shrubs. 

Dominant 

floristics 

Environmental 

relationships 

Dominated by A. raddiana associated with A. Senegal and Balanites. of the shrub 

cover, Leptadenia pyroiechnica, Calotropis procera and Boscia senegalensis are 

common species. 

The typical community of free-draining soils in the Sahel Zone. Along the line of 

the 500 mm (20 in) isohyet it grades into the Xnogeissus-dominated communities of 

the Sudan Zone. 

Species list Traverse in the Banawa Dunefield, Land System Vd2 (Table 24, Column 4). 

32 CORDIA ROTHII/ACACIA RADDIANA TREE AND SHRUB SAVANNA (WITH THICKETS) 

Physiognomy A mosaic of open tree savanna interspersed with areas of aggregated small trees and 

shrubs which can develop into tangled thickets with a dense growth of climbers 

supported by the erect growth. 

Dominant 

floristics 

Environmental 

relationships 

Can be considered as a variant of Community 31, with the A, raddiana Tree and Shrub 

Savanna forming a matrix in which are dispersed the thickets of Cordia rothii, 

Commiphora africana, C. quadricincta with the climbing Salvadora persica and 

Leptadenia arborea. 

In the project area this community occurs only in the extreme northeast, where the 

mean annual rainfall falls below 380 mm (15 in). It is common on the sands of the 

Arege Plain, Land System Vel and on the sand islands of the Yo Alluvial Plain, 

Land System Vf3. 

Species list Traverse in the Arege Plain, Land System Vel, (Table 24, Column 3). 

148



Common trees & shrubs Cotranon SDecies on llthosols MAR>30Qm £J0 lnj_ 

C. glutlnosura — l ~ ~ \ 

\ 

Plllostlgna retlculatum — M l . 

Common trees A shrubs MAR > 750 mm (30 (n) 

VIT.*»» «ImpllrtfnllA 


MAR 500. l COO mm (20 - ^0 In) 

Dalberg!» mPlannrylnn 

Common trees & shrubs MAR < 500 mm (20 jnj 

•• • 

firaria rtifrifpnnl 

RurkM afrtcnn» 

Arafin hnrfclt 

AfzflUa afriranA 

S T rtfli7.uill 

t 

-Jpi- RpfflirlnARa vtmsft ^1 M 

__ 1 . 

Acacia raddlana M — A. spnpgal 1 - -W • i 

Rnmmllln rinlKlulM 

s 

Pseudocedrfila kntsrhyl 

Hauelea lat I folia 

-4 . --T--TTT -TTT 

t__i u \ A, prtlyarnnr.hn/rampylflânr.ho ^H | 

• 

- --U. 

- -JÉ 

, 

S 

—• l —• • Jr 

i :• ~l*~ 

t"I -T 

~m --] 

' M V' 

' 'JL 

' ~TT H 


wansnnlfl dlfjltnta II • ! H • 

Ar.nr.in alhida W PW • P 


Rare species 

l IIvartA rhAmap 

149 

npllln nPltlrtlfnl \n 

Addendum 

Securlneea »Irosa 

linnen sp. _I_ 

/

33 LEPTADENIA SHRUB SAVANNA 

Physiognomy An open shrub savanna with few emergent trees. 

Dominant A species composition similar to Community 31 but with the tree cover destroyed, 

floristics 

Environmental An anthropic derivative of Community 31. 

relationships 


34 ARISTIDA/ANDROPOGON GRASSLAND 

Physiognomy A well developed grassland standing 1-2 m (3-6 ft) high. Shrub growth is rare but 

occasional tall emergent trees occur, standing to 10-13 m (33-43 ft). 

Dominant 

floristics 

Environmental 

relationships 


35 CHAD FRINGE COMPLEX 

The sward dominated by Ariatida spp. and Andropogon gayanua. This has been 

described as var. bisquamulatus but is more probably the sub-Saharan var. 

tridentatua. The emergent trees are almost entirely Acacia albida and 

Sclerocarya birrea. 

This community, the so-called 'Manga Grasslands', occurs only in the far north of 

the project area on the extremely free-draining dune of the Zigindi Plain, Land 

System Vbl. It forms a break in the otherwise continuous belt of Acacia raddiana 

Tree Savanna (Community 31). It has been suggested that resorting of soil particles 

resulting in a change of mechanical composition, in particular the fine sand/coarse 

sand ratio, can effect a swing from annual to perennial grassland. Further studies 

are required to elucidate fully the relationships of this interesting community. 

Apart from Mimosa pigra and occasionally elements of Community 36 on island sites, 

there are no woody communities of significance in this complex. It is dealt with 

under 'Grassland' in Volume 4. 

150

36 NORTHERN ALLUVIAL COMPLEX 

The spatial relationship of the major plant communities in this complex are shown 

in Figure 15. In addition to elements of Communities 27, 28, 29, 31, 32 and 33, 

the balance of the woody vegetation can be considered as comprising two plant 

communities, listed below as 36a and 36b, distributed along rivers and streams and 

alluvial plains in the northern Sudan and the Sahel Zones. 

36a HYPHAENE PALM SAVANNA AND PALM BUSH 

Physiognomy At full development, tall dense stands of the palm attain heights of the order of 

10 m (33 ft). Where heavily utilised, thickets of palm regrowth develop. 

Dominant 

floristics 

Environmental 

relationships 


Near-pure stands of H. thebaica with occasional shrubs of Ziziphus spp. and 

Acacia spp. 

Favoured sites are sand islands and sand drift either over, or influenced by, 

halomorphic clays. 

36b MITRAGYNA/ACACIA NILOTICA RIPARIAN WOODLAND 

Physiognomy Tall fringing woodland standing to as much as 13 m (43 ft) high. 

Dominant 

floristics 

Environmental 

relationships 


Dominated by M. inermis and the varieties of A. nilotica and other Acacia spp. 

Kigelia africana is not uncommonly found in this community. 

River and stream banks. Wet islands in floodplains. 

151

37 SOUTHERN ALLUVIAL COMPLEX 

37a BORASSUS PALM SAVANNA 

The spatial relationship of the major plant communities in this complex are shown 

in Figure 15. In addition to elements of Communities 10, 16, 17, 18, 27, and 28, 

the balance of the woody vegetation can be conveniently classified as four plant 

communities, listed below as Communities 37a to 37d. This complex occurs in the 

major part of the Sudan Zone, the Sub-Sudan Zone and, excepting the Deji/Gaji 

river system on the Kerri Kerri Plateau (Land Systems Illbl and IIIb2), the 

Northern Guinea Zone within the project area. 

Physiognomy Tall, often regularly spaced stands of the palm attaining as much as 25 m (80 ft) 

in height. Usually in floodplain grassland with limited low shrub growth beneath. 

Dominant 

floristics 

Environmental 

relationships 


Near-pure stands of B. aethiopicum. Shrub growth is typical of Community 12. 

In the project area confined to floodplains or sometimes river terraces with high 

watertables. 

37b MITRAGYNA/CELTIS RIPARIAN WOODLAND 

Physiognomy Typically closed woodland at full maturity with tall trees rising to as much as 

25-30 m (80-100 ft) in height. A dense understorey of low trees, shrubs, climbers 

and thicket species. 

Dominant 

floristics 

Environmental 

relationships 

Species list 

37c KHAYA/DANIELLIA WOODLAND 

Physiognomy 

Dominant 

floristics 

Environmental 

relationships 

Species list 

37d SALIX/MIMOSA SHRUB SAVANNA 

Physiognomy 

Dominant 

floristics 

Environmental 

relationships . 


A variable community, M. inermis and C. integrifolia are highly typical species 

together with Acacia spp. and several species like Khaya and Vitex also common in 

farm parklands. 

Streamsides and water edges. 

Based on observations on the Gongola and Kilunga rivers (Table 25, Column 1). 

Tall woodland, with widely spaced emergents rising to heights of the order of 

30 m (100 ft). Often with a closed canopy at full development and restricted 

shrub growth below. 

Characterised by the conspicuous presence of K. senegalensis. D. oliverii is 

commonly also present. These are interspersed with elements of Community 19 and 

occasional riparian trees. 

Typically forming a fringing woodland to the main riparian or swampside growth. 

Based on observations on the Kilunga and Loko rivers (Table 25, Column 2). 

Thick shrubland rising to 3-5 m (10-16 ft). 

The woody component of this community is composed almost entirely of w. pigra and 

S. 1edermannii. 

Occurs on rock areas in stream beds where the Salix is particularly conspicuous 

and also on denuded stream banks where the Mimosa predominates. 

152


Community Number 37b 37c 38o 38b Community Number 37b 37c 38a 38b 

Common trees A shrubs Common species on Uthosols MAR>900mm (30 In) 

UM 

c, glirtlnnmm ' 

Plltostl0na ret leu la tum. / 

Annona HPnÊfllpnfll'fi ' 

/ T, ri»1*1pl1l 

::ic::::::::: _ 

_•___ 

. .. j . 

Common trees & shrubs MAR > 750jp £3,0 ln^ I::II V-XX- :i::::::: M- 

1 1! • 

L" 1 n 

Arnica fllhlrtn 

. ,/ ,/ 

• I 

VU.PT fllmp-MMtolla 

::::::::::JLI: 


.. 

. it 

1 m 

fl:._ 

. .1 

1 m W 

/ fi._ m 

m. 

i ai •_ MM K 

nanlellla nl Jv0.-I 1 •_ MM 


-- i' ZZJK:::::: 

.__JL..._- 

.__JL..._- 

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38 DEJI VALLEYS COMPLEX 

The plant communities associated with the incised valleys in the Kerri Kerri Plateau, 

Land System Illdl, are unique in the project area and carry a vegetation typical of 

more southerly wetter areas of Nigeria. In the light of our present knowledge the 

woody communities can be conveniently classified under four main headings, 38a to 

38d below. Further investigation could well justify further subdivision of this 

classification. The vegetation is probably a reflection of near Northern Guinea 

climatic conditions, the persistence of flow in the rivers themselves and the low 

anthropic impact in this area. 

38a RAPHIA/MACARANGA RIPARIAN FOREST 

Physiognomy Dense forest with emergents rising to over 30 m (100 ft) with a confused well 

developed series of sub-storeys. There is a rich shrub layer and ground flora. 

Dominant 

floristics 

Environmental 

relationships 

Dominated by palm species, particularly R. sudanica. There is a high proportion of 

broad-leaved trees. High stands of Pandanus candelabrum are a feature. 

Occupying the banks of the rivers and swamps of the complex. 

Species list A partial list based on Keay (1962) and Tuley (1970) (Table 25, Column 3). 

38b FICUS CONGENSIS WOODLAND THICKET 

Physiognomy Dense close stands of colonial fig with numerous stilt roots, standing to as much as 

12-15 m (40-50 ft) high. On some islands it occurs as an outer waterside zone with 

an inner core of slightly higher broad-leaved trees. 

Dominant 

floristics 

Species 1 ist None. - 

Pure stands of F. congensis. The associated species in the zonal areas appears at a 

distance to be a Syzygium sp. but could be one of the similar broad-leaved trees 

like Garcinia ovalifolia. 

38c KHAYA/DANIELLIA/PTELIOPSIS WOODLAND 

Physiognomy Tall woodland standing to about 15 m (50 ft) with typically a closed canopy and 

restricted shrub growth beneath. 

Dominant 

floristics 

Environmental 

relationships 

Very similar to Community 37c but differing primarily in the more conspicuous 

presence Of D. Oliverii and Pteliopsia spp. 

Occurs as a belt of fringing woodland between Community 38a and the interfluve 

vegetation. 

Species list Based on Keay (1962) and Tuley (1970) (Table 25, Column 4). 

38d PTELIOPSIS HABEENSIS WOODLAND THICKET 

Physiognomy Physiognomically unique in the project area. The trees comprise numerous thin 

trunks, coppice-like and uniform in thickness. A woodland thicket is formed rising 

to 10-13 m (33-43 ft) in height. Little light is admitted and the ground cover is 

sparse. 

Dominant 

floristics 

Environmental 

relationships 


Pure stands Of P- habeenais. 

Occurs along the smaller streams running into the main rivers. The reason for its 

occurrence is by no means clear but it appears to be associated with a combination 

of a riparian habitat with exposed or near-exposed rock in the valley bottoms. 

Sandstone rock is invariably exposed in the stream bed where this community occurs, 

sometimes carrying 'rock species' like Croton zambesicua. The woodland thicket 

commences a few yards back from the stream bank and occupies a belt some 20-45 m 

(70-150 ft) wide. 

154

•&*& 

1 ^ f ^ ' ^ " ^^5|$ÉÊ&& 

PLATE 1/15 Hyphaene Palm Bush on the Yobe Ploodplain. 

^ J 

PLATE 1/16 Riparian Woodland on the course of the River 

Yedseram. north of the Bama Ridge. March 1967. 

155

FAUNA 

by 

P J Aitchison and P E Glover 

Wild animals, apart from small mammals, birds, lizards and monkeys are not common in the 

North East project area except in a few remote tsetse-infested areas like the Yankari Game 

Reserve and the reed and papyrus swamps around Lake Chad. This paucity in the fauna is in 

sharp contrast to East and Central Africa. Nevertheless a large variety of species have been 

recorded from the area (Rosevear, 1953). 

MAMMALS 

Of the more spectacular game animals, herds of elephant, Loxodonta africana, have been seen 

in the Gongola Valley and in the swamps near Pika. Bushcow or buffalo, Syncems nanus, are 

widespread but shy and seldom seen, occurring in the Guinea and Sudan zones but not in the 

Sahel zone. Giraffe, Giraffa camelopardalis peralta, is reputed to occur in the Yankari 

Game Reserve. In the past, they have been recorded near Azare and near Biu, but they are 

now either extinct or exceedingly rare. The black rhinoceros, Diceros bicomis, has been 

recorded in the North East but it has not been seen for many years. Hippopotamus, 

H. amphibuus, is found in the Benue river, the Gongola and its tributaries, and in the swamps 

of Lake Chad. 

Lists of the more common mammals found in the project area are shown in Tables 26-31, at the 

end of this section. 

REPTILES 

Among the larger reptiles, three species of crocodile occur in northern Nigeria: the Nile 

crocodile Crocodylus niloticus; the long-snouted crocodile C. calaphactus; and the broadfronted 

crocodile Osteoloemus tetraspis. The sacred crocodiles in Lake Tilla near Biu are 

well known. Two species of monitor lizard are common, the aquatic Varanus niloticus and the 

land lizard V. exanthematicus. Large yellow, red and blue Agama lizards are abundant 

everywhere and chameleons are regularly seen. Snakes are numerous, although not often seen, 

three of the more common ones being puff adders, cobras and pythons. 

BIRDS 

In contrast to the scarcity of large mammals, birds are numerous in the North East. 

Vultures and crows are common around most of the towns and villages. Magpies are said to be 

associated with the presence of Borassus palms (Elgood, 1960). Storks, pelicans, crested 

cranes, egrets, ducks and a number of other birds can be seen wherever there is water, 

especially on the shores of Lake Chad and along the rivers running into it (Buxton, 1935). 

The ostrich occurs, but is now very rare indeed. Bush fowl, Francolinus, are ubiquitous, 

particularly one species which lives in the gardens around the towns and villages; guinea 

fowl, both wild and domesticated, are common everywhere. Smaller birds such as pigeons, 

waxbills, sparrows, weavers, sunbirds, thrushes, cuckoos, shrikes, orioles and starlings are 

abundant. Weavers often assume the proportions of a major agricultural pest (Crook and Ward, 

1968; PAO, 1965). 

INSECTS 

Pull treatment of this topic is clearly beyond the scope of this study. Bibliographic data 

are however widely available and Posnett et al. (1971) is of specific application to Nigeria. 

Tsetse and related biting flies are the subject of Volume 2. Due to their impact on land 

resources the following merit special, if brief, mention. 

156

Locusts The North East is particularly sensitive to attack by both the Desert and 

Migratory Locust. Although free of major attack for some years, there have been recent upsurges 

and there is no justification for relaxing vigilance. Apart from spectacular attacks, 

considerable routine damage is done by non-gregarious forms (Betts, 1961; Bullen, 1969; Popov 

and Ratcliffe, 1968; Waloff, 1966). 

Simulium This fly and the dreaded disease of river blindness that it carries are prevalent 

in the Hawal and Kilunga/Loko river systems. It is often the limiting factor in the development 

of fertile alluvial areas (Hunter, 1966; Ovazza et al. 1965). 

Termites These insects play a significant role in the ecosystem, particularly in the 

tropical environment obtaining in the project area. They can be pests of crops, destructive 

to wooden structures and active in pedogenetic processes. The distribution of species and 

the characteristics of their nests and mounds can be employed as useful indicators of such 

environmental parameters as soil type, water regime and fire regime (Bouillon, 1964). 

EXTERMINATION OF GAME 

Apart from Rosevear (1953), there is very little information about present-day wildlife in 

the North East. On a tour covering more than 6 500 km (4 000 mi) between October and 

November 1965, and taking 6 weeks, the writers saw 2 red-fronted gazelle in a field near 

Song, a couple of warthog, several troops of baboons and some monkeys. Hyaenas were heard in 

a few places at night. At Potiskum hyaenas are sacred and a number of them live in caves in 

the ironstone. Two baby hyaenas were seen on a lead in the town. 

Davies (1956) gives a list of animals found in the Biu area during his time there. He 

mentions lion, leopard, cheetah, wild dog, hyaena, jackal, bushcow, roan antelope, waterbuck, 

kob, gazelle, reedbuck, duiker, two species of hartebeest. and even giraffe and aardvark. 

During our stay of a week at Biu we saw not even one of these animals. Davies also mentions 

that there has been a great reduction of game in the area in the past 50 years and says that 

a missionary wrote of a hunt in 1931-32 in the Garkida district reporting that he saw 15 roan 

antelope, a drove of 30 pigs, numerous small antelope, a big warthog, reedbuck, waterbuck, 

bushbuck, buffalo, lion, a herd of 16 giraffe, a drove of 50 baboons and some hyaenas. He 

seems to think it unlikely that all these animals could have been seen on one hunt, but in 

parts of East Africa even today it would be possible to see that number of animals in the 

course of an hour or so. In the 15 months that Davies spent at Biu, which included about 100 

days on tour, he saw only baboons, monkeys, duiker, gazelle, leopard and hyaena and also a 

variety of small mammals, snakes and insects. However, the true situation regarding the 

abundance of game in this area in the past is confusing because Davies quotes the following 

passage written in 1907 in the Biu District Commissioner's journal: 'I am much disappointed 

to find how completely the game is disappearing. Some two years ago there was a fair 

amount of game around Wuyo'. Game drives in the Biu District which used to be arranged in 

the rains were rather a thing of the past by 1954, when an organised baboon hunt was not a 

great success. 

There is no doubt that wildlife has become dangerously depleted. 

In most modern societies regulated hunting is not generally a serious factor in reducing the 

incidence of wildlife. In fact, it has been demonstrated (Glover, 1964) that in other parts 

of Africa it is virtually impossible to exterminate some of the smaller species of ungulates 

such as bushbuck, duiker and warthog by organised hunting. In many other territories of 

Africa it is not overhunting that has depleted the wildlife hut the destruction of its 

habitat by intensive land use and mounting human population pressure. In Nigeria however 

hunting would indeed appear to be largely responsible for so sadly reducing the number of 

game animals in most parts of the country. Petrides (1965) considers that 4 000 000 muzzle 

loaders or "Dane guns' is a conservative estimate for Nigeria, many of them illegally made by 

local 'gunsmiths'. 

Where there is protein-deficiency in the diet, the economic value of "bush meat' could be, 

and probably is, very great. Petrides (1965) quotes March as estimating that 50 per cent of 

all meat eaten in Northern Nigeria comes from wild animals, but the Game Warden at Bauchi 

puts the figure at 25 per cent. Accepting the lower figure of 25 per cent to be more 

realistic, the economic value of game meat eaten in Northern Nigeria annually must be in the 

neighbourhood of at least £2 500 000 and this sum would increase if more animals were 

157

available. Cattle, sheep and goats are incomparably more destructive to the natural habitat 

than a varied natural fauna. In addition the food requirements of the natural fauna are 

complementary and in balance with the resources of the area. Further, unlike most breeds of 

domestic stock, the indigenous ungulates are tolerant of trypanosomiasis. 

In addition to the black rhinoceros, now extinct in Northern Nigeria, it is generally 

accepted that the following animals are also facing extermination: ostrich, hunting dog, 

cheetah, lion, leopard, giraffe, hippopotamus and klipspringer. Eventually however all the 

animals will go, except perhaps a few small mammals such as rodents and bats, unless a 

concentrated and determined effort is made now by Government to preserve more extensively 

this most valuable economic asset. That it can be done has been proved by the outstanding 

success achieved so far in the Yankari Game Reserve. It is therefore essential that as many 

areas of this kind should be set aside as possible. It is even suggested that if approaches 

were made to institutions such as the World Wild Life Fund, the International Union for the 

Conservation of Nature, and the East African Wild Life Society, it might be possible to 

hasten the process of rehabilitation by restocking with animals from the teeming game parks 

of eastern Africa. 

158

TABLE 26 Mammals common throughout the North East 

West African bushbuck 

Western defassa waterbuck 

Buffon's kob 

Aardvark/ant bear 

African wild cat 

Egyptian mongoose 

Marsh mongoose 

Senegal genet 

Speckle-throated otter 

Cape clawless otter 

Ratel/honeybadger 

Hunting dog 

Pale fox 

West Coast mammilate rat 

Giant rat 

Nile harsh-furred rat 

Patas monkey 

Tantalus guenon 

Angola free-tailed bat 

Common African leaf-nosed bat 

Yellow-winged bat 

Tomb bat 

Pallid fruit bat 

Straw-coloured fruit bat 

Nigerian hedgehog 

159 

Tragelaphus script us 

Kobus defassa unctuosus 

Adenota kob 

Orycteropus a fer 

Felis lybica 

Herpestes ichneumon 

Atilax paludinosus 

Genetta genetta senegalensis 

Lutra maculicollis 

Aonyx capensis capensis 

Mellivora capensis 

Lycaon pictus 

Vulpes pallida 

Rattus coucha erythroleucus 

Cricetomys gambianus 

Arvicanthis niloticus 

Erythrocebus patas patas 

Cercopithecus aethiops tantalus 

Tadarida angolensis 

Hipposideros caffer 

Lavia frons 

Taphozous mauritianus 

Epomophorus anurus 

Eidolon helvum 

Atelerix spiculus

TABLE 27 Mammals recorded in the Sahel Zone 

Dorcas gazelle Gaze 11a dorcas dorcas 

Dama gazelle Gazel la dama dama 

Situtunga Limnotragus spekii** 

Scimitar oryx Oryx algazel algazel 

Striped hyaena Hyaena•hyaena 

Common jackal Canis aureus 

Small crested porcupine Hystrix cristata aerula' 

Jerboa Jaculus jaculus 

Chad ground squirrel Xerus erythropus chadensis 

Lake Chad hare Lepus chadensis 

Diana musk shrew Crocidura hindei diana*** 

TABLE 28 Mammals recorded in the Sudan and Sahel Zones 

Hasler's red-fronted gazelle Gaze 11a rufifrons hasleri 

Senegal hartebeest Damaliscus korrigum 

Soemering's cheetah Acinonyx jubatus soemeringii 

Caracal/desert lynx Felis caracal 

Nigerian striped weasel Poecilictis libyca rothschildi* 

Senegal striped polecat Ictonyx striates senegalens is* 

Mrs Buchanan' s dormouse Graphiurus olga* 

Dainty fat mouse Steatomys cuppedius 

Hausa pygmy mouse Mus haus sa 

Kabwir spiny mouse Acomis johannis 

Schlieffen's bat Nycticeius schlieffeni 

* Largely confined to the north of the project area. 

** Confined to the swamps round Lake Chad. 

*** Confined to the extreme northeast corner of the project area. 

160

TABLE 29 Mammals recorded in the Sudan Zone 

Side-striped jackal Canis adust us 

Angelus gerbil Taterillus gracilis angelus 

Nigerian hairy-soled gerbil Gerbillus gerbillus nigeriae 

Buchanan' s dwarf gerbil Desmodilliscus braueri buchanani 

Northern Nigerian hare Lepus ganopus 

Midas bat Tadarida ruppellii 

Bauchi musk shrew Crocidura arethusa 

TABLE 30 Mammals recorded in the Guinea Zone 

Western hartebeest Alcelaphus buselaphus maj or 

Red-flanked duiker Cephalophus rufilatus 

Ruddy mongoose Herpestes sanguineus 

Pox's dormouse Graphiurus toxi 

Fox's brush-furred rat Uranomys foxi 

Tullberg' s rat Rattus tullbergi 

Pygmy mouse Mus musculoides 

Spotted grass-mouse Lemniscomus striatus 

Southern Nigerian hare Lepus zechi 

Nigerian free-tailed bat Tadarida nigeriae 

Yola free-tailed bat Tadarida websteri 

Dark brown bat Scotophilus nigrita 

Small dark bat Scotophilus nigritellus 

White-winged bat Nycticeius albfuscus 

Giant leaf-nosed bat Hipposideros gigas 

Pox' s horse-shoe bat Rhinolophus foxi 

Large-eared slit-faced bat Nycteris macrotis 

Dwarf epaulet bat 

Epomophorus pus il lus 

Pox's musk shrew Crocidura foxi 

161

TABLE 31 Mammals recorded in the Guinea and Sudan Zones 

Oribi Ourebia ourebio 

Klipspringer Oreotragus oreotragus* 

Roan antelope Hippo tragus equinus** 

Nigerian reedbuck Redunca redunca nigeriensis 

Grimm' s duiker Sylvicapra grimmia 

Warthog Phacochoerus aethiopicus 

Western dassie/hyrax Procavia ruficeps 

Leopard Panthera pardus 

Serval cat Felis serval 

Spotted hyaena Crocuta crocuta 

White-tailed mongoose Ichneumia albicauda 

African civet Civettictis civetta 

Cutting grass Thryonomys swinderianus 

Senegal crested porcupine Hystrix cristata senegalica 

Dalton's mouse Rattus daltoni 

Graceful gerbil Taterillus gracilis gracilis*** 

Kemp's gerbil Tatera kempii 

Red-legged ground squirrel Xerus erythropus eryihropus 

Giant pangolin Manis gigantea** 

Dog-faced baboon Papio anubis 

Senegal galago Galago senegalensis senegalensis 

Midge pipistrelle Pipistrellus Culex**** 

Variegated butterfly bat Chalinolubus variegata**** 

Thebes bat Nycteris thebaica 

Common slit-face bat Nycteris his pi da 

Egyptian fruit bat Rousettus aegyptiacus 

Gambian fruit bat Epomophorus gambianus**** 

Mann' s musk shrew Crocidura mannii' 

Giffard's musk shrew Crocidura giffardi 

*' Mainly N. Guinea and the Sub-Sudan areas east of Bauchi. 

** Widespread but seldom seen. 

••* Primarily a Sudan species but occurs in the extreme north of the 

Guinea Zone. 

•*•* Mainly N. Guinea but occurs in the south of the Sudan Zone. 

162

BISTORY 

by 

P Tuley 

To give this subject adequate treatment is beyond the scope of this study. The project area 

is remarkably well documented and.has a long history of trans-Saharan contact with the 

Mediterranean littoral and trans-Sudanian contact with the Nile Valley and the Middle East. 

Posnett et al. (1971) devote a section of their Nigerian bibliography to this topic for 

those seeking further information. All that can be attempted here is a brief review of past 

events that are of some relevance to the present-day structures and land use. 

In many ways the present administrative arrangements (Text Map 14) are a reflection of the 

history of the area. Bornu Province is the successor to the long-standing Bornu Kingdom. 

This Kingdom, itself once part of the even larger one of Kanem that encircled Lake Chad, has, 

allowing for the ebb and flow of conquest and defeat, stood as a coherent entity through the 

centuries approximating, on the western side of the lake, to the present boundaries. 

To the westward a reasonably stable boundary has been maintained first with the great Sudan 

Kingdoms, then the Hausa States and the Pulani Emirates that followed. To the southward the 

depredations of the Jukun were eventually survived until the Jukun themselves fell before the 

Pulani advance. To the north the principal danger has been from Berber and Arab invasions 

and Zinder, in the past nominally a fief of Bornu, often proved a most troublesome vassal. 

Friction within the mother kingdom of Kanem and invasions from the area of the Nile Valley 

have troubled the land. One such invasion in the late nineteenth century, commanded by the 

Sudanese adventurer Rabeh, led to the defeat of the kingdom that had stood so long as a 

cultural unit. The advent of the European powers led to the defeat of Rabeh and their 

administrative boundaries during the colonial period closely followed the original structures, 

although Dikwa was separated from Bornu. In 1961, after a plebiscite organised by the 

united Nations, the northern area of the Cameroons under British mandate since the end of the 

1914-18 World War, voted to- join Nigeria and is now part of the North-Eastern State. 

Throughout the long span of history the pagan hill people in the south and east of the 

project area have survived the assaults and slave raids of successive cultures in the most 

remarkable fashion, relying on the rigours of the terrain to protect them against the 

advanced arms and cavalry of their foes. Some of these attained a fair degree of administrative 

structure. Not all the southern groups were hill-dwellers. Some, largely of Jukun and 

Bantu origins, have occupied extensive lowland areas over many of which the later Pulani 

Emirs maintained only a tenuous hold. However, these groups and the hill people were 

extremely vulnerable at harvest time and often paid tribute to the Fulani to protect their 

crops. Loose confederations, such as the chieftancy system based on Hong, were a feature of 

these societies. 

On the west and southwest a series of smaller emirates evolved as a 'buffer zone' between 

Bornu and the larger Fulani Emirates and a whole range of ethnic groups were able to resist 

complete assimilation by the major powers on either side. Thus today we see the project 

area, now representing the greater part of the North-Eastern State in the Federation of 

Nigeria, with the relict kingdom in the northeast, surrounded by a ring of small units, 

formerly lying between Bornu and the Fulani Empire or carved out of areas of Jukun/Bantu 

influence in the Gongola and Benue Valleys. However, among the hills, mountains and 

plateaux and to a lesser extent the lowlands, the tribal structure of many pagan or ex-pagan 

groups survives largely intact. 

163

POPULATION 

by 

P Tuley 

The distribution of population is shown in Text Map 12* and a table of population figures by 

administrative district is given in Volume 5. As can be seen from the map, excluding the 

major towns, the main centres of population lie in the foothills of the Mandara Range and 

the Yedseram Valley, the plains to the east and northeast of Maiduguri, the plains around 

Potiskum and the lower Gongola Valley. Although the density around Biu is to be expected, 

the continuation throughout the hilly basement areas around Gombi is notable. The broad 

location of the main ethnic groups is shown in Text Map 13, and many of the district names 

shown on Text Map 14 are indicative of tribal nomenclature. 

Only a brief outline of the various ethnic groups is appropriate here. However the relationship 

between cultural groupings and population pressures on the structure of present land use 

must not be overlooked. Ethnic considerations must also influence planning proposals and 

this subject receives further treatment in Volume 4. There is much interesting reading 

available, a bibliography of which is contained in Posnett et al. (1971). 

The Kanuri 

The Kanuri are the descendents of the original inhabitants of the Kanem and Bornu Kingdoms. 

Today they represent approximately half of the population of Bornu Province. The rural 

communities are typically mixed farmers, keeping a range of stock and raising arable crops. 

The Shuwa Arabs 

This small group of settled migrants originated in the Nile Valley. They are mostly found 

round the periphery of Lake Chad and in the Dikwa area, where they are often settled on sand 

islands among the clay plains of the area. They are also largely mixed farmers. 

The Fulani 

The Fulani, of long standing in the project area, are associated with the emirates 

established at the conquest of the Jukun Empire. Therefore in centres such as Yola and Gombe 

are found Pulani dignitaries and a town-dwelling community, the Fulanen Gidda. The traditional 

Pulani (Bororoje) is however a nomadic pastoralist. Over the past few years there has 

been a steady influx of Pulani herdsmen, greatly adding to the number already in the project 

area, being driven from the north and northwest by the increasing arable acreages and the 

ploughing up of traditional dry season grazing areas for rice production. 

The Hausa 

The Hausa are typically arable farmers. Primarily domiciled in the central plains in the 

north of Nigeria, their distribution impinges on the west of the project area. In addition 

there have been steady migratory movements by them into the major towns and other parts of 

the area, particularly the unoccupied heavy clay lands of the Gongola Valley. 

* Based on the 1963 Population Census. Although outdated it still gives a useful visual picture of 

the concentrations of population. 

164

Other Groups 

In addition to the major well known groups, a multiplicity of tribal units are to be found. 

In the literature they are often grouped as 'pagan hill tribes'. While it is true that many 

of them have survived Pulani and other attacks by virtue of the defensive advantage offered 

by the upland areas, it should also be recognised that substantial tribal units have occupied 

lowlands or relatively accessible plateaux over the passage of years. Many of these have 

complex tribal histories of conquest and migration unrelated to the later struggles with the 

Pulani, and many Jukun and Bantu influences remain to this day. Traditional farming 

practices range from elaborate terracing to typical shifting cultivation. 

165

COMMUNICATIONS 

by 

P Tuley 

The major features of the communications system are shown in Text Map 15. As the project 

area has recently been the subject of a road development survey (Scott, Wilson, Kirkpatrick 

and Partners, 1964-9) little more need be added here. However the subject is dealt with 

under Agricultural Potential in Volume 4 and where appropriate under the land system 

descriptions in Volume 3. Two features merit special mention. In an area relatively well 

served with roads, the absence of adequate communication along the north bank of the Benue 

is a noticeable break in the network. The problems of keeping roads open during the rains 

on the black cracking clays should also be noted. This is of particular relevance to the 

international link between Maiduguri and Port Lamy in the Chad Republic. 

Waterways 

The Benue is navigable as far as Yola for 4 months of the year and constitutes an important 

trade link with the delta ports and markets such as Onitsha. A considerable volume of 

produce from both Chad and Cameroon also passes to the world markets via this route. Plans 

for barrages on both the Benue and the Gongola could well improve this means of communication 

in future. Two motor ferries at Numan and Yola give access to the southern part of the 

North-Eastern State. 

Air Travel 

There is a regular service linking the international airport at Kano with Maiduguri and Yola. 

In view of the distances involved there is every merit in the improvement of both light and 

routine commercial air services as an aid to development. 

166

10' 

D.O.S.(LR.)3064Q 


MILES 0 25 

I I I I I L 

„ Main Road 

H 1 I- Railway 

* + + + + + + + International Boundary 

POPULATION DENSITY TEXT MAP 12 

_L 

12° East of Greenwich 14" 

Based on figures derived from the 1963 population census. 

Drawn and photographed by Directorate of Overseas Surveys 1969. 


10* 

ETHNIC GROUPS 

12* 

14° 

TEXT MAP 13 

1 1 s- \ 1 ^ |I4- 

B" OMauena 

SCALE 1:3,000,000 \ . 

MILES 0 25 50 75 100 MILES ./ 

***** ******* V^ 

* * • • ** *« „ iV 

KANURI 

N( "ru Gashua 

o / / ^^v 

j ^ * ^ k»i 

*y d. ^ X 

VsJHadejia J-jS Z//j B E U D E \ 

^^z^zyy^y^^0y^^^. 

» H » r / KANURI 

H » r / KANURI 

H r / KANURI 

o fc. * Geidam/ 

^--^ o is 

/ jS*//I Mon 

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ '//VV MAIDUGURly^ 

~"""-*-*-^ ( Q / x/\ \(*AHQjrfy / ^' ib sFA f' 

/ TANGALE . UJA'IA KANAKURÂ\ /%/ .* 

BURUMAWA/ KZ ..• ,X««.,«*P V^son, fy/>>J^y 

1 V^_^ : ""^>V. \° V/1 K/J * 

\ , WURKUM BAC^foltJ^' J^L ^vL-*** 

JARAWA ^ >/ ONumin \ l//v H/L* 

BASHAR 1 ^ / roiadv!/ \^7 

YERGAM / :z22 

i 

+ + ••• + •+ __ International Boundary 

i 

?rr*sw_*i 

^> 

Main trend of recent movement 

of pastoralists - mainly Fulani 

Main trend of recent influx of 

cultivators - mainly Hausa 

Land over 1500 feet 

10* 12° East of Greenwich 14* 

D.O.S.(L.R.)30MX 


169 

I 

10 

1 —Ip 

Drawn and photographed by Directorate of Overseas Surveys, 1970

UJuJ 

CO 

10° 

^WUKARI 

105 

D.O.S.(L.R.)3064S 


1 Matsena 

2 Nguru 

J Yusufari 

4 Borsari 

5 Geidam 

A Mobber 

7 Gubio 

8 Kanembu 

9 Nganzie 

10 Mongonu 

II Bedde 

12 Fune 

13 Damaturu 

14 Magumeri 

lb Marte 

16 Ngala 

ADMINISTRATIVE UNITS TEXT MAP 14 

17 Rann Kalabalge 35 Askira 

18 Potiskum 

19 Fika 

36 Shani 

20 Gujba BAUCHI PRC 

21 Kaga 

22 Auno 37 Katagum 

n 

Yerwa 38 Gamawa 

24 Mafa 39 Sokwa 

25 Konduga 40 Itas 

2ft Gumsu 41 Udubo 

27 Gulumba 42 Jamaare 

28 Margi 43 Madara 

29 Bama 44 Shira 

30 Woloji 45 Giade 

31 Babur 46 Chinade 

17 Tera 47 Dambam 

11 West Bura 48 Dagaudu 

34 East Bura 49 Jalam 

J_ 


BOUNDARIES 

International __ + + ^ + + + + + + + + + 

State ^ _ . _ . ^ . ^ _ 

Provincial 

Divisional 

District 

Hardawa 

Yerima 

Darazo 

Ganjua 

Dukku 

Nafada 

Kwami 

Galenbi 

Kirfi 

Ako 

Gom be 

Yamaltu 

Duguri 

Fali 

Gwana 

West Tangale 

Kaltungo 

Waja Longuda 

Dadiya 

Kindiya 

ADAMAWA PROV 

Muri 

Wurkum 

Bachama 

Longuda 

Shellem 

Ga'anda 

KMba 

Uba 

Mbula 

Yungur 

Song 

Zummo 

82 

83 

84 

Girei 

Ribadu 

Malabu 

SARDAUNA PROVINCE 

85 Belel 

06 Sorau 

8/ Maiha 

88 Mubi 

89 Mayo Mbani 

90 Michika 

91 Madagali 

92 Gwoza 

KANO PROVINCE 

93 Birniwa 

94 Kaugama 

95 

96 

9/ 

98 

Kirikasama 

Gurri 

Auyo 

Kafin Hausa 

Auyo 

Kafin Hausa 

99 Bulangu 

100 Gwaram 

PLATEAU PROVINCE 

01 Kanam 

102 Wase 

103 

104 

Plain Yergam 

Resettlement 

BENUE PROVINCE 

105 Kinda Kuvyo 

14° 

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Civil Airfield © 

Landing Strip -1 

Vehicle Ferry VF 

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Drawn and photographed by Directorate of Overseas Surveys, 1970.

AUBERT G 

AUBERT G 

BARBER W 

BARBER W and 

JONES D G 

BAWDEN M G 

CARROLL D M and 

TULEY P 

BATOEN M G and 

TULEY P 

BETTS E 

BIGELSTONE H J 

BOCQUIER M 

BOCQUIER M and 

GAVAUD M 

BOUILLON A ed 

BULLEN F T 

BUXTON P A 

CARROLL D M 


HOPE W A 

CARTER J D and 

BARBER W 

CARTER J D 

BARBER W 

TAIT E A and 

JONES G P 

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USAID 

UNITED STATES 

DEPARTMENT OF AGRICULTURE 

SOIL SURVEY STAFF 

UNITED STATES 

DEPARTMENT OF AGRICULTURE 

SOIL SURVEY STAFF 

WALOFF Z 

WALTER M W 

WRIGHT J B 

ZONNEVELD I S 

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182

PUBLICATIONS OF THE LAND RESOURCES DIVISION 

These publications have a restricted distribution and are not available to booksellers. The 

Division makes a report on each completed project. The report is published as a Land 

Resource Study or Technical Bulletin only with the consent of the government concerned. The 

abbreviated titles of the reports in the style of the 'World List of Scientific Periodicals' 

are Land Resour. Stud, and Tech. Bull. Land Resour. Div. Overseas Dev. Admin. 

BAWDEN N G and 1961 

LANGDALE-BROWN I 

BAWDEN M G and 1963 

STOBBS A R 

LANGDALE-BROWN I and 1963 

SPOONER R J 

BAWDEN M G (Ed) 1965 

LAND RESOURCE STUDIES 

SPOONER R J and 1966 

JENKIN R N 


TULEY P 


CARROLL D M 

JENKIN R N and 1968 

POALE M A 

BLAIR RAINS A and 1968 

McKAY A D 

HILL I D 1969 

VERBOOM W C and 1970 

BRUNT M A 

AITCHISON P J and 

GLOVER P E 

AITCHISON P J 

BAWDEN M G 

CARROLL D M 

GLOVER P E 

KLINKENBERG K 

LEEUW P N DE and 

TULEY P 

1970 

1972 

TECHNICAL BULLETINS 


BASCOMBE C L 

1967 

PIGGOTT C J 1968 

•Out of print. 

••Land Resource Study No. 7 has not yet been published. 

R 6019/8842/12 700 10/71 TP 183 

An aerial photographic reconnaissance of the present and 

possible land use in the Bamenda Area, Southern Cameroons.* 

The land resources of Eastern Bechuanaland. 

The land use prospects of Northern Bechuanaland. 

Some soils of Northern Bechuanaland with a description of 

the main vegetation zones. 

The development of the Lower Mgeta River Area of the 

United Republic of Tanzania. Land Resource Study No. 1. 

The land resources of Southern Sardauna and Southern 

Adamawa Provinces, Northern Nigeria. Land Resource Study 

No. 2. 

The land resources of Lesotho. Land Resource Study No. 3. 

An investigation of the coconut-growing potential of 

Christmas Island. Volume 1, The environment and the 

plantations. Volume 2, Appendixes. Land Resource Study 

No. 4. 

The Northern State Lands, Botswana. 

No. 5. 

Land Resource Study 

An assessment of the possibilities of oil palm cultivation 

in Western Division, The Gambia. Land Resource Study No. 6 

An ecological survey of Western Province, Zambia, with 

special reference to the fodder resources. Volume 1, 

The environment. Volume 2, The grasslands and their 

development. Land Resource Study No. 8.** 

The land resources of North East Nigeria. Volume 2, Tsetse 

and Trypanosomiasis. Land Resource Study No. 9. 

The land resources of North East Nigeria. Volume 1, 

The environment. Land Resource Study No. 9. 

Notes on the soils of Lesotho. Technical Bulletin No. 1. 

A soil survey of Seychelles. Technical Bulletin No. 2.

9 The Land Resources of North East Nigeria A/blume1 The ...

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