Africa—too wet or too dry?
Africa has long been regarded as a continent of low average population density, but the difficulties this continent has in supporting itself have been thrown into sharp relief by the droughts. The continent of Africa extends about 30 degrees north and south of the equator and presents a cross section of many of the world’s principal climates. In large parts of the Sudano-Sahel, the ground is flat and the vegetation consists of strips of steppe vegetation interspersed with ruined soil. The vegetation is in a very delicate state of natural equilibrium, and every disruption of the vegetative cover—for instance, due to excessive grazing—destroys that cover and causes an expansion of soil destruction. There are large areas of Africa where rivers exist only intermittently. Dry river valleys are occasionally washed by powerful floods of water, sometimes suddenly. Far below large areas of the dry and inhospitable sand and rock of the Sahara lie vast quantities of groundwater.