ABSTRACT
A geotechnical study of organic Holocene estuarine silty clays (locally known as Hippo Mud) in the greater Durban area, South Africa, is presented. The study area occurs in the lower reaches of the Mhlangane River and comprises a soil profile, up to 15 m, of highly compressible Hippo Mud overlain by more recent alluvial sediments and underlain by weathered Permian shale bedrock. Various laboratory tests were undertaken to predict the soil’s physical behaviour and facilitate comparisons with tests from other areas underlain by similar material so that prediction could be made about its properties. Geochemical tests show the samples to contain smectite and illite clay minerals, plagioclase and quartz, with the provenance terrain being the lower and middle Ecca Group, which dominate the drainage basin. Other areas where these soils are likely to be found are in incised coastal valleys north of Durban where the Permian Ecca Group shales form the drainage basin.
