When the Turkana Basin was not dominated by river systems, the rock record indicates several paleo-lakes occupied the region and sometimes reached over 100 kilometers away from the present lake margin. Instead of just recording the depositional environments that have occurred, a field geologist will try to determine the causes of such changes in order to reconstruct what the landscape looked like at different periods of time. Why did fluvial systems occupy the Turkana Basin for a greater period of time than lakes? How do lakes form? Where does it get its water? And other questions that will not be answered in this module – What type of life occurred in the Turkana Basin? Where? When? Why in that particular location?
To start, it’s important to know that the Turkana Basin is located within the East African Rift System (diagram below) and within a depression between the Ethiopian and Kenyan domes. As a result of tectonic processes and magmatic activity, Africa is slowly splitting apart in the eastern part of the continent and has created a rift valley. Some geologists believe this region may extend far enough to create a sea, such as the Red Sea, or possibly an ocean. For now, faults and volcanic dams along the rift valley have created a number of basins that is mostly occupied by lakes.