Little is known about the timing of dune-building episodes in the southwestern Kalahari Desert. Previously, arid phases when dune activity occurred have been inferred from gaps in chronologies derived from information that attests to former humid periods. To redress this, optically stimulated luminescence (OSL) dating was applied to sediment samples taken from a range of aeolian landforms in the SW Kalahari. Four periods of dune building are identified in the late Pleistocene and Holocene. Holocene aeolian activity at 6 ka and 1-2 ka led to the construction of localised dune forms, in contrast to late Pleistocene times when the extensive field of linear dunes that dominates the region was emplaced. Late-Holocene aridity was however sufficient to allow rapid emplacement of the lunette dune at Witpan. The record of aeolian activity is evaluated in the context of humid chronologies and an ocean-atmosphere model of Holocene climate change, with good agreement obtained. It is concluded that the application of optical dating to a range of aeolian landforms has the potential to establish the style as well as timing of dune-building. It is also demonstrated that the climate during dune-building periods must have differed significantly from the prevailing semi-arid climate with drought periods of today, which may have been the predominant climate regime through much of the Holocene.
Bard, E., Hamelin, B., Fairbanks, R.G. and Zindler, A.1990: Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U-Th ages from Barbados corals. Nature345, 405-10.
5.
Beaumont, P.B., van Zinderen Bakker, E.M. and Vogel, J.C.1984: Environmental changes since 32,000 BP at Kathu Pan, northern Cape. In J.C. Vogel, editor, Late Cainozoic palaeoclimates of the southern hemisphere, Rotterdam: Balkema, 329-38.
6.
Bousman, C.B., Partridge, T.C., Scott, L., Seaman, M., Metcalfe, S.E., Vogel, J.C. and Brink, J.S.1988: Palaeoenvironmental implications of late Pleistocene and Holocene valley fills in Blydefontein Basin, Noupoort, CP., South Africa . Palaeoecology of Africa19, 43-67.
7.
Bowler, J.M.1973: Clay dunes: their occurrence, formation and environmental significance. Earth-Science Reviews9, 315-38.
8.
— 1986: Spatial variability and hydrologic evolution of Australian lake basins. Palaeogeography, Palaeoclimatology, Palaeoecology54, 21-41.
9.
Brook, G., Cowart, J.B. and Marais, E.1997: Wet and dry periods in the southern African rainfall zone during the last 300 kyr from speleothem, tufa and sand dune data. Palaeoecology of Africa, in press.
10.
Bullard, J.E., Thomas, D.S.G., Livingstone, I. and Wiggs, G.F.S.1994: Analysis of linear sand dune morphological variability, southwest Kalahari Desert. Geomorphology11, 189-203.
11.
— 1996: Wind energy variations in the southwestern Kalahari Desert and implications for linear dunefield activity. Earth Surface Processes and Landforms21, 263-78.
12.
— 1997: Dunefield activity and interactions with climatic variability in the southwest Kalahari Desert. Earth Surface Processes and Landforms, in press.
13.
Butzer, K.1984: Late Quaternary environments in South Africa. In Vogel, J.C., editor, Late Cainozoic palaeoclimates of the southern hemisphere, Rotterdam: Balkema, 235-64.
14.
Butzer, K., Stuckenrath, R., Bruzewicz, A. and Helgren, D.1978: Late Cenozoic palaeoclimates of the Gaap Escarpment, Kalahari margin, South Africa. Quaternary Research10, 310-39.
15.
Cohen, A.L. and Tyson, P.D.1995: Sea-surface temperature fluctuations during the Holocene off the south coast of Africa: implications for terrestrial climate and rainfall . The Holocene5, 304-12.
16.
Deacon, J. and Lancaster, N.1988: Late Quaternary palaeoenvironments of southern Africa . Oxford: Clarendon Press , 225 pp.
17.
Eriksson, P.G., Nixon, N., Snyman, C.P. and Bothma, J. du P.1989: Ellipsoidal parabolic dune patches in the southern Kalahari Desert. Journal of Arid Environments16, 111-24.
18.
Goudie, A.S. and Thomas, D.S.G.1985: Pans in southern Africa with particular reference to South Africa and Zimbabwe. Zeitschrift für Geomorphologie NF29, 1-19.
19.
Heine, K.1982: The main stages of the late Quaternary evolution of the Kalahari region, southern Africa. Palaeoecology of Africa15, 53-76.
20.
Huntley, D.J., Godfrey-Smith, D.I. and Thewalt, M.L.W.1985: Optical dating of sediments: Nature313, 105-107.
21.
Lancaster, N.1981: Palaeoenvironmental implications of fixed dune systems in southern Africa. Palaeogeography, Palaeoclimatology, Palaeoecology33, 327-46.
22.
— 1986: Pans of the southwestern Kalahari: a preliminary report . Palaeoecology of Africa17, 59-67.
23.
— 1988: Development of linear dunes in the southwestern Kalahari, southern Africa. Journal of Arid Environments14, 233-44.
24.
— 1989: Late Quaternary palaeoenvironments of the southwestern Kalahari. Palaeogeography, Palaeoclimatology, Palaeoecology70, 367-76.
25.
Livingstone, I. and Thomas, D.S.G.1993: Modes of linear dune activity and their palaeoenvironmental significance: an evaluation with reference to southern African examples. In K. Pye, editor, The dynamics and environmental context of aeolian sedimentary systems, Geological Society Special Publication 72, 91-102.
26.
Murray, A.S., Olley, J.M. and Caitcheon, G.G.1995: Measurement of equivalent doses in quartz from contemporary water-lain sediments using optically stimulated luminescence . Quaternary Science Reviews14, 365-72.
27.
Nanson, G.C., Chen, X.Y. and Price, D.M.1992: Lateral migration, thermoluminescence chronology and colour variation of longitudinal dunes near Birdsville in the Simpson Desert, central Australia. Earth Surface Processes and Landforms17, 807-19.
28.
Rendell, H.M., Yair, A. and Tsoar, H.1993: Thermoluminescence dating of periods of sand movement and linear dune formation in the northern Negev, Israel. In K. Pye, editor, The dynamics and environmental context of aeolian sedimentary systems, Geological Society Special Publication72, 69-74.
29.
Rhodes, E.J.1988: Methodological considerations in the optical dating of quartz. Quaternary Science Reviews7, 395-400.
30.
Sarnthein, M.1978: Sand deserts during glacial maximum and climatic optimum . Nature272, 43-46.
31.
Scott, L. and Bousman, C.B.1988: Palynological studies of hyrax middens from southern Africa . Palaeogeography, Palaeoclimatology, Palaeoecology76, 367-79.
32.
Scott, L. and Brink, J.S.1991: Quaternary palaeoenvironments of pans in central South Africa: palynological and palaeontological evidence. South African Geographer19, 22-34.
33.
Shaw, P.A. and Thomas, D.S.G.1996: The Quaternary palaeoenvironmental history of the Kalahari, southern Africa. Journal of Arid Environments32, 9-22.
34.
Smith, B.W., Rhodes, E.J., Stokes, S. and Spooner, N.A.1990: The optical dating of sediments using quartz. Radiation Protection Dosimetry34, 75-78.
35.
Stokes, S.1991: Optical dating of coversands. Geologie en Minjbouw70, 327-37.
36.
— 1992: Optical dating of young (modern) sediments using quartz: results from a selection of depositional environments. Quaternary Science Reviews11, 153-59.
37.
— 1994: Optical Dating of selected Late Quaternary Aeolian Sediments from the Southwestern United States. Unpublished D.Phil thesis, University of Oxford.
38.
Stokes, S. and Breed, C.S.1993: A chronostratigraphic re-evaluation of the Tusayan Dunes, Moenkopi Plateau and southern Ward Terrace, northeastern Arizona. In K. Pye, editor, The dynamics and environmental context of aeolian sedimentary systems, Geological Society Special Publication 72, 75-90.
39.
Stokes, S. and Gaylord, D.R.1993: Optical dating of Holocene dune sands in the Ferris dune field, Wyoming. Quaternary Research39, 274-81.
40.
Stokes, S., Thomas, D.S.G. and Shaw, P.A.1997: New chronological evidence for the nature and timing of linear dune development in the Southwest Kalahari Desert. Geomorphology, in press.
41.
Thackeray, J.F. and Lee-Thorp, J.A.1992: Isotopic analysis of equid teeth from Wonderwerk Cave, northern Cape Province, South Africa. Palaeogeography, Palaeoclimatology, Palaeoecology99, 141-50.
42.
Thomas, D.S.G.1984: Ancient ergs of the former arid zones of Zimbabwe, Zambia and Angola. Transactions of the Institute of British Geographers NS9, 75-88.
43.
— 1988: The geomorphological role of vegetation in the dune systems of the Kalahari. In G.F. Dardis and B.P. Moon, editors, Geomorphological studies in southern Africa, Rotterdam : Balkema, 145-58.
44.
Thomas, D.S.G. and Shaw, P.A.1991: The Kalahari environment. Cambridge : Cambridge University Press, 284 pp.
45.
Thomas, D.S.G., Nash, D.J., Shaw, P.A. and van der Post, C.1993: Present day lunette sediment cycling at Witpan in the arid southwestern Kalahari Desert. Catena20, 515-27.
46.
Thomas, D.S.G., Stokes, S. and O'Connor, P.W.1997: Late Quaternary aridity in the southwestern Kalahari Desert: new contributions from OSL dating of aeolian deposits, northern Cape Province, South Africa. In Alsharan, A., Glennie, K.W. and Whittle, G.L., editors, Quaternary deserts and climate change, Rotterdam: Balkema, in press.
47.
Tyson, P.D.1986: Climatic change and variability in southern Africa . Oxford: Oxford University Press , 220 pp.
48.
Tyson, P.D. and Lindesay, J.A.1992: The climate of the last 2000 years in southern Africa . The Holocene2, 271-78.
49.
Vogel, J.C.1983: 14C variations during the upper Pleistocene. Radiocarbon25, 213-18.
50.
Wells, G.L.1983: Late-glacial circulation over central North America revealed by aeolian features. In Street-Perrot, F.A. , Beran, M. and Ratcliffe, R., editors, Variations in the global water budget , Dordrecht: Reidel, 317-20.
51.
Wiggs, G.F.S., Livingstone, I., Thomas, D.S.G. and Bullard, J.E.1994: The effect of vegetation removal on airflow structure and dune dynamics in the southwest Kalahari. Land Degradation and Rehabilitation5, 13-24.
52.
Wiggs, G.F.S., Thomas, D.S.G., Livingstone, I. and Bullard, J.E.1995: Dune mobility and vegetation cover in the southwest Kalahari desert. Earth Surface Processes and Landforms20, 515-30.
53.
Wintle, A.G.1993: Luminescence dating of aeolian sands: an overview . In K. Pye, editor, The dynamics and environmental context of aeolian sedimentary systems, Geological Society Special Publication 72, 49-58.
