Denudation rates for the southern Drakensberg escarpment, SE Africa, derived from in-situ- produced cosmogenic 36 C1: initial results

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Abstract
Cosmogenic 36 C1 concentrations in basalt samples from the Drakensberg escarpment on the SE African passive margin give quantitative estimates of denudation and scarp retreat rates. Over the 10 4 –10 6 year timespan addressed by these data, the calculated escarpment retreat rate has been 50–95 m Ma -1 and the average summit denudation rate 6 m Ma -1 . The scarp retreat rate is an order of magnitude less than previously suggested. The rate of summit lowering is sufficient to prevent the long-term intact survival of erosion cycle surfaces formed in the Mesozoic that were previously inferred for this region.