Lunette dunes in the northeast Cape, South Africa, as geomorphic indicators of palaeoenvironmental change

Abstract

Three lunette dunes occur on the southern shore of a pan on the farm Buffelsfontein above the Great Escarpment in the northeastern part of the Eastern Cape Province, South Africa. The two inner lunettes are formed of silt and clay, and the third of fine sand. The location of these dunes is anomalous as lunette dunes are rare in the wetter parts of the southern African subcontinent. The two inner lunette dunes lie along the downwind margin of a present day pan, while the third lunette is associated with the margin of a large palaeopan. The morphometry of the Buffelsfontein pan/lunette dune series was investigated using aerial photography and field surveys. Sedimentological and geochemical techniques were applied to investigate the lunette and pan floor sediments and to assist in the elucidation of processes responsible for the development of the lunettes. Sedimentological differences in the pan fringing lunettes suggest two very different sediment sources related to changing geomorphic conditions, possibly since the last glacial maximum. The pan/lunette complex offers a unique opportunity to quantify these changes as local rainfall records are available for the past 100 years.