ABSTRACT
The equatorial highlands of East Africa are bisected by the north-south trough of the Rift Valley. They contain marked variations in altitude, precipitation and vegetation, as well as in their exploitation in recent centuries by hunters, herders and cultivators. The contrasts are especially sudden and striking at Engaruka, situated at the foot of the eastfacing Rift wall at three degrees south (Fig. 11.1). At an altitude of 1000 m (which is low for this interior region) and with unreliable and variable rainfall, estimated at not more than 400 mm in an average year, it is a relatively hot, dry and dusty place with high evapotranspiration. Despite the attraction of a permanent supply of clear water in the Engaruka river, no cultivators would ever have contemplated settling here by relying on the rain alone for their crops.
