The role of Quaternary environmental change in the evolution of landscapes: case studies from southern Africa

The paper begins by examining the importance of southern African Quaternary environmental change. The Quaternary is characterised by repeated climatic changes of considerable amplitude; analysis of these fluctuations reveals the ubiquity of change and the fundamental dynamism of earth systems. Chang e is normal and, despite the fact that southern Africa was not subject to Q uaternary glaciation per se, the influence of variations in, say, amount an d seasonality of rainfall, has been very marked indeed. The Quaternary also represents the time period during which people have become a dominant envi ronmental agent in the subcontinent; southern Africa has played a crucial r ole in the evolution of hominids and their development has been influenced strongly by accompanying environmental change. The relationship between geo morphology and climate in southern Africa is explored, revealing the degree and extent to which its landscapes are determined by changing environmenta l conditions, especially during the Tertiary and Quaternary; how apparent i s the legacy of the past? This leads to a consideration of the types of geo morphological evidence, some more reliable than others, that can be utilise d in order to reveal the details of Quaternary environmental change. Arid a nd semiarid landscapes appear to preserve more evidence of former environme ntal conditions, although high contemporary erosion rates and the paucity o f long terrestrial-sedimentary sequences hinder their complete elucidation. Two case studies of Quaternary change in the subcontinent are presented, f rom the southwestern Cape and Namibia. These examples document the increasi ng intensity of human impact on landscapes to the extent that people now pl ay the dominant geomorphological role, especially in semiarid and coastal a reas. The conclusion offers pointers as to how geomorphological evidence of Quaternary change can be used to assist in the better management of contem porary and future environmental conditions. (C) 2001 Elsevier Science B.V. All rights reserved.