The stretching and break-up of east Africa, a process that is ongoing, could have been prolonged and widespread, reports a study published online this week in Nature Geoscience.
Eric Roberts and colleagues reconstruct changes in drainage patterns and landscape development in east Africa, using dated volcanic ash deposits to help determine the precise timing of any changes. Eastern parts of Africa are today breaking away from the remainder of the continent, but the split divides into two segments - an eastern and a western branch. Stretching and sinking of the crust along the eastern branch was thought to have begun millions of years before the western branch. However, the data show that rivers in the area had reversed direction and begun to fill lakes created by the sinking crust in western parts before about 25 million years ago - a time coincident with sinking and stretching in the east.
The data imply that the initiation of break-up of eastern Africa could have been broadly synchronous with that of the western branch.