Terracettes and active gelifluction terraces in the Drakensberg of the Province of Eastern Cape, South Africa: a process study

Abstract

Terracettes and turf-banked terraces exist at Tiffindell Ski Resort in the Drakensberg of the Province of the Eastern Cape at altitudes between 2750 m and 2880 m on slopes of between 15°and 26°. Ice lenses and interstitial ice exist within turf-banked terraces in winter. During post-winter thaws, soil moisture reaches saturation in at least the upper part of the regolith in which turf-banked terraces occur. These terraces move downslope under the influence of gelifluction (which is essentially a combination of frost creep and solifluction). Terracettes appear to move as a result of frost creep, processes associated with needle ice, and slope wash. Both turf-banked terraces and terracettes are part of the periglacial environment and are active under present climatic conditions at Tiffindell.