Quaternary International 89 (2002) 151–164 Geomorphic evidence for late Quaternary environmental change from the eastern Great Karoo margin, South Africa D.S. Thomas a , P.J. Holmes b, *, M.D. Bateman a , M.E. Marker b a Sheffield Centre for International Drylands Research, Department of Geography, University of Sheffield, Sheffield S10 2TN, UK b Department of Environmental and Geographical Science, University of Cape Town, Rondebosch 7701, South Africa Abstract The eastern margins of the Great Karoo, South Africa, represent a transition zone between the semi-arid shrublands of the Karoo to the west and the moister grasslands of the east. For this reason, the surficial sediments and younger geomorphic features of the area might reliably be expected to record evidence for environmental change, particularly with regard to the precipitation record and phases of greater aridity as the boundary of the Karoo migrated in response to climate change during the Late Quaternary. The high altitude catchment on which we report here is situated on the inland flank of the upwarped South African Great Escarpment, which here forms the Stormberg range. The catchment is unique in that a number of geomorphic features have, within their structure, preserved evidence of aeolian, fluvial and colluvial processes, which were active in the past. We present evidence from a variety of depositional landforms and sedimentary deposits that suggests that Late Quaternary climates in the eastern Karoo have been both moister and significantly more arid than at present, as well as displaying a greater seasonality in rainfall. r 2002 Elsevier Science Ltd and INQUA. All rights reserved. 1. Introduction Situated between B231S and B351S, South Africa’s latitude is such that much of the country is vulnerable to small-scale climatic changes (Tyson, 1986; Preston- Whyte and Tyson, 1988). Typically, the vast, semi-arid interior of the subcontinent known as the Karoo, lying between B291S and B341S, and to the west of the 500 mm isohyet, is no exception. Meadows and Baxter (1999) make the point that an appreciation of environ- mental change in the Late Quaternary has important implications for accurate predictions with respect to future change. The question of such a change is not merely academic, as even relatively small changes in rainfall will have significant implications for human activity in the semi-arid Karoo. From an environmental change perspective, the Karoo region is understudied relative to other parts of the subcontinent (Holmes, 1998). With the possible exception of a multidisciplinary investigation undertaken by Bousman et al. (1988), when research into Late Quaternary environmental change in the Karoo has occurred, it has generally been both discipline- and site-specific. This paper reports on the findings and palaeoenvir- onmental implications from a series of Late Quaternary sedimentary sequences in the eastern Great Karoo, a rain-shadow dryland area located north of the Great Escarpment on the eastern margin of the larger Karoo region (Fig. 1). Aeolian, fluvial and slope processes have interacted to produce an environment which is unique in terms of both the variety and spatial concentration of depositional environments. The paper aims therefore to contribute to a better overall understanding of geo- morphic processes and, by inference, environmental change within this under-researched subregion of southern Africa. 2. Physical setting The study area is situated 200 km north of the Eastern Cape coast of South Africa (Figs. 1 and 2), on the northern flanks of the upwarp that forms the Stormberg Mountains of the Great Escarpment. The mean altitude of the area is B1800 m above sea level. Geologically, the area comprises Molteno and Elliot Formation mudstones and sandstones of the Mesozoic Karoo *Corresponding author. Tel.: +27-21-650-2881; fax: +27-21-650- 3791. E-mail address: holmes@enviro.uct.ac.za (P.J. Holmes). 1040-6182/02/$-see front matter r 2002 Elsevier Science Ltd and INQUA. All rights reserved. PII:S1040-6182(01)00086-6