Name: Lake Turkana
Location: Kenya, East Africa
Age: Pliocene/ Pleistocene (4-0 Ma)

Geological History of the Lake Turkana Basin

Lake Turkana basin and the different geological sites. Adapted from Brown et al. (2001).

The present day Lake Turkana lies in a basin that has a varied history. A lake has only filled the basin for a small fraction of the last four million years. The ancient Lake Lonyumn filled the basin between 4.2 and 4.0 million years ago. The ancestral Keriu River once drained into this lake from the south and created a delta over time. The fossiliferous sediments at the Kanapoi site are from sediments of this river. Allia Bay formed after the filling of Lonyumn Lake. Approximately 4 million years ago, sediments from the ancient Omo, Turkwel, Kerio and other smaller rivers had filled the basin.

These rivers continued to flow over the extensive flood plains. The ancestral Omo, which flows northwards into Ethiopia, has been the dominant river ever since. The Allia Bay site is associated with the channel of this river. The various fossils recently unearthed in Lake Turkana, probably would have been carried by these various rivers in the water medium and deposited in the sediment. Many of the fossils found in the bed of Lake Turkana are rolled and weathered, indicating that they have been transported a long distance and possibly reworked by older sediments. The better-preserved fossils are found nearer the top of the bed, at higher horizons.

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