212 R. R. Walls — The Geology of Portuguese Nyasaland. 



raised beaches in so many places. In the extreme west of the country 

 the water-level of Lake Nyasa has been observed to fall considerably 

 during the short time it has been known to Europeans. The want 

 of water is terrible nov«', and is reflected in the annual famines and 

 rapidly dwindling native population. The absence of water has 

 been the most serious drawback to the development of this country, 

 and demands immediate and careful study. Water can always be 

 obtained by digging in the sand in the synclines and valleys and a 

 few native wells exist in these situations, but no serious attempt 

 has been made by Europeans to exploit these sources for water. 

 It is not a difficult matter for a field geologist to map out likely 

 sources of water, or to suggest suitable situations for boring ; for 

 example, the syncline between the two north-south ridges and the 

 narrow strips immediately to the east and west of these ridges are 

 good regions for a constant water supply, and are, in fact, the most 

 fertile parts of the country. The River Montepuesi, where it crosses 

 the syncline between these two ridges, broadens out into the great 

 Lake Biribizi, which remains a swamp for months after the river 

 has disappeared. This suggests that engineering attempts might 

 be made to deflect the rivers in their short season into natural 

 synclines to form lakes and so conserve the water supply. Water 

 is also retained in the porous Tertiary rocks along the shores of the 

 Indian ocean, whence it is already obtained by boring wells, as 

 described above. 



From the economic point of view, Portuguese Nyasaland is a 

 decidedly poor country. Its mineral wealth, in spite of numerous 

 reports to the contrary, appears to be nil. Its chief asset is the rich 

 loose soil which results from the disintegration of the gneiss and 

 granite, and which is exceedingly fertile when water can be obtained. 

 The country will probably develop into a rich agricultural state once 

 water supply has been assured. The rainfall is considerable, although 

 the wet season is short, but exact figures are lacking. A large 

 proportion of this rainfall is already conserved in the deep loose 

 deposits which fill up the synclines and river valleys. Once the 

 sub-arenaceous contours of the hard metaraorphic rocks are plotted 

 and new wells made in the larger synclines and valleys, the conditions 

 in this impoverished country will be greatly ameliorated. 



