COSMOGENIC 21Ne AND 10Be REVEAL A MORE THAN 2 Ma ALLUVIAL FAN FLANKING THE CAPE MOUNTAINS, SOUTH AFRICA

Cosmogenic 21 Ne and 10 Be analyses across a subhorizontal fossil alluvial fan flanking the Cape Mountains near Laingsburg (Western Cape, South Africa) indicate a formation age for this fan of at least 2 Ma. Maximum erosion rates obtained from samples of quartzite ridges protruding through the fan alluvium deposits are very low (