Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne

Measurements of cosmogenic He-3 and Ne-21 concentrations in dolerite and quartzite samples front selected sites across the South African coastal escarpment and the interior plateau provide valuable estimates of the short-term (i.e., a few hundred thousand years) denudation rates. Present-day denudation rates at the summit of the escarpment and on the inland plateau are more than an order of magnitude lower than those in the Cretaceous. Values between 1.0 and 2.1 m/Ma obtained from resistant quartzite samples and between 1.5 and 3 m/Ma from dolerite sills suggest a strong lithology control on the erosion. The observed patterns of denudation across different landform sites on the high plateau and along its flanking escarpment suggest that the morphology of the sampling sites together with the local climate conditions have controlled the denudation processes.