East African Lakes
Lake Naivasha and all other Kenyan lakes are a product of the seismic movements that forged the eastern branch of the Great African Rift Valley. This ancient great depression, divided into 2 main branches separated by Lake Victoria, is visible from space. It runs from Mozambique to the Red Sea and is still actively widening today. Considered in its integrity, it contains some 35 tectonic or graben lakes that originated through the filling of single or multiple faulted troughs, which developed due to the rifting mechanism; for example: Lakes Baringo and Nakuru. At the same time, the rift -especially its eastern branch- harbours lakes that originated in relatively recentl geologic times (middle Peistocene) through the filling of ancient craters (calderas) of volcanos that accompanied the dramatic fractures of the earth crusts that are taking place in this part of the world, for example: Lakes Naivasha and Oloidien. The Eastern Branch of the rift includes all East African lakes, aligned in a sequence running from Lake Manyara and Lake Natron in Tanzania, to Lake Naivasha, Baringo and Turkana in Kenya, to lake Shala and Bishoftu in Ethiopia (to name just a few). In the eastern branch, lakes tend to be relatively small, shallow and saline, due to the prevailing arid climatic conditions, and to the lack of an outlet. The western branch lakes are instead larger, deeper and freshwater, due to moister climates.
Lake Naivasha is one of the few rift lakes together with lake Baringo, situated some 150 km to the north, to be freshwater. Both lakes are located in a dry climate similar to the one experienced by other saline lakes, however they have a subterranean outlet. This ensures a continuous removal of water charged with salts. Thanks to the outlet, no long-term accumulation of salts leached from the alkaline, sodium and hydrogen carbonate-rich volcanic rocks that abound in their basins takes place in these lakes. Naivasha is the rift lake situated at the highest altitude (1888 m a.s.l.) of all other rift lakes; this a characteristic ensures that no crocodiles can survive here, and that mosquitos are free of malaria because the Plasmodium parasite cannot adapt to the altitude.
