Geological results of the Uganda Museum’s Baker Centenary Expedition stressed the importance of rift control in land-surface development and sedimentation since early Miocene times.

The Kisegi-Wasa area north of the fault “nose” of Ruwenzori exposes late Tertiary sediments that grade upward without angular discordance into a thick conformable series of gently dipping lacustrine deposits (Kaiso Series) which yield abundant mollusk and fish fossils but few mammal fossils. The mammals are typical of shallow-water conditions and include species recorded from the lower Villafranchian of North Africa. Higher in the sequence occur forms that range through the upper Villafranchian, whereas the uppermost...