Isostatic Anomalies and Crustal Structure in the Southern Cape

It has been found that there is a general tendency for the isostatic anomalies to be negative in the region between the escarpment and the sea. The authors consider that these negative anomalies arise from the compensation of topography which has been removed by erosion. The paper discusses the negative anomaly in the Southern Cape. It is found that at least 1.4 km has been removed over a strip 80 km wide. The stress differences which result are of the order of 2.3 × 108dyn/cm2 while the load is being carried by both crust and mantle. If the crust is floating on the mantle the stresses in the crust are of the order of 120 × 108dyn/cm2 in the centre of the strip.