The Terraced landscapes of The MalTese Islands - Landscape Europe

1 | Chapter 24: Rolé
7 : Quarries and subsidence structures in Maltese landscapes
Maltese buildings are nearly all constructed from blocks of globigerina limestone. These have given the urban landscape a particular character which successive
planning instruments have sought to preserve (Planning Services Division 1990). The negative aspect of these policies is that the rural landscape
of the islands is marred by a series of spent, or still active, quarries (Figures 15 and 16).
A related problem is the disposal of inert material originating from excavated rock and demolished constructions. This accounts for about 95% of the
material which used to be dumped at Malta’s main landfill site; located at Maghtab. The obvious solution was to utilise this inert material to refill the spent
quarries and rehabilitate such sites for arable cultivation. However, strict controls were necessary to ensure that the fill material contained no contaminants
which could threaten the quality of groundwater supplies.
While this may appear to be an innovative environmental scheme, there are some interesting precedents. For several decades, small quarries in
Malta were filled with inert building spoil. In several cases these were then used for citrus orchards, since citrus trees are particularly prone to wind damage.
Moreover, the artificially deep soil retains far more moisture than the usual, relatively shallow Maltese soils.
Other depressions have been used in cultivation for far longer. These are subsidence structures which are typical of karstic lithology and originate
from collapsed caves which leave distinctive round depressions on the surface (dolines). These sites are attractive to farmers because they are sheltered
from strong winds and retain moisture well, like the spent quarries. Another advantage is that they contain deeper soils than the surrounding limestone
plateaux and such soils are normally augmented rather than eroded.
The older dolines are normally used for cultivation; like Hofret-ir-Riz (hofra means hole in Maltese) and that of Bahrija. Both of these are located
on the upper coralline plateau. A more recent subsidence produced Il-Maqluba and written records indicate a date of November 1343 (Pedley, et al 2002).
This feature is not used for cultivation; possibly because there is no easy access to the floor. This has permitted the development of an interesting vegetation
community which is currently protected by environmental legislation (Figure 17).
Figure 15. Active hardstone (Coralline limestone) quarry
producing crushed gravel and sand for concrete slurries
– Ghar Lapsi
and its need to fill specific agricultural quotas. The Maltese wine industry is playing a lead role in this process
since it needs to obtain high quality Maltese grapes in order to satisfy DOC requirements. It has been reported
that several hectares of abandoned and degraded terraced lands have been rehabilitated and planted with vines
(Role et al. 2005) (Figure 13). Future sustainable management of these landholdings may reverse the widespread
perception that viticulture is often responsible for high rates of soil erosion and land degradation (as
reported by Brandt and Thornes 1996; Grove and Rackham 2001; Geeson, Brandt, and Thornes 2002)
A similar process applies to the planting of olive groves on terraced land. Some of the more interesting
cases involve the setting up of organic olive groves which command premium prices for extra high quality
olive oil. This high level of added value is giving a new lease of life to terraced cultivation and it should, hopefully,
be emulated elsewhere. Moreover, the practice of minimum-to-zero tillage in cultivation, as well as
extensive soil mulching, are having significant positive impacts on soil conservation. Other benefits include
water conservation since the need for irrigation is kept at a minimum.
Figure 16. Active softstone (Globigerina) quarry
producing stone blocks for building - Dwejra, Gozo
Pedroli B, Van Doorn A, De Blust G, Paracchini ML, Wascher D & Bunce F (Eds. 2007).
Europe’s living landscapes. Essays on exploring our identity in the countryside. LANDSCAPE EUROPE / KNNV.
Figure 17.– Il-Maqluba – a collapsed cave structure
reported to have occurred in November 1343. Il-Maqluba
now shelters an interesting vegetation community which is
currently protected by environmental legislation