A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

Due to deep chemical weathering, rock outcrops are rare in this area. In some
localities quartz floats are present in the soil.
The geology is made up of quartzo-fiedspathic gneisses, which are also jointed in some
areas. In most cases, these joints show a high intensity of weathering and the quartz
and feldspar show myrmekitic structure. Within this area, quartz veins ranging from 0.10
to 0.35m in thickness, and pegmatites cut the gneisses at an oblique angle. The quartz-
feldspar crystals increase in size towards the centre of the pegmatite. The contact
between the pagmatites and the country rock is abrupt (Kemp, 1975).
2.2.1.3 Topography
The Ntchenachena Area is a continuation of the East Nyika escarpments and is part of
the Great African Rift Valley system (Kemp, 1975). The area is a belt of rugged country,
consisting mainly of deeply dissected spurs which are almost funnel shaped (Figure 2.6)
and much of it is almost inaccessible. Altitude varies significantly from 1295m to 1828m
above sea level (GoM, 1987). Flat areas are concentrated along the valleys.
22