Kenya and Ethiopia - March 5th, 2010
Lake Turkana, formerly known as Lake Rudolf, is a lake in the Great Rift Valley in Kenya, with its far northern end crossing into Ethiopia. It is the largest permanent desert lake in the world and also the world’s largest alkaline lake.
The rocks of the surrounding area are predominantly volcanic. Central Island (visible in the center of the lake upon opening the full image) is an active volcano, emitting vapors. Outcrops and rocky shores are found on the East and South shores of the lake, while dunes, spits and flats are on the West and North, at a lower elevation.
The lake is an East African Rift feature. A rift is a weak place in the Earth’s crust due to the separation of two tectonic plates, often accompanied by a graben, or trough, in which lake water can collect. Currently the graben is 320 km wide in the north of the lake, 170 km in the south.
The visible tectonic features of the region result from extensive extrusions of basalt over the Turkana-Omo basin in the window 4.18-3.99 mya. These are called the Gombe Group Basalts. They are subdivided into the Mursi Basalts and the Gombi Basalts.
The two latter basalts are identified as the outcrops that are the rocky mountains and badlands around the lake. Short-term fluctuations in lake level combined with periodic volcanic ash spewings over the region have resulted in a fortuitous layering of the ground cover over the basal rocks.