Geoscience Reference
In-Depth Information
Figure 8.13. Map of the late Cenozoic Kalahari Sands. (After Cooke,
1958
.)
in effective precipitation was necessary for dune formation and, most probably, an
increase in windiness.
The linear dunes of the Kalahari are the most comprehensively dated dunes in
southern Africa, but the interpretation of the luminescence ages has been a thorny
problem. Initial work by Stokes et al. (
1997
;
1998
) appeared to indicate multiple
episodes of dune construction and inferred aridity in southern Africa during the last
interglacial-glacial cycle at 115-95, 46-40, 26-20 and post-20 ka. The depositional
gaps were considered to correspond to wetter climatic phases. These climatic fluctu-
ations were thought to be associated with changes in sea surface temperatures in the
south-east Atlantic and Indian Oceans, leading to changes in temperature gradients
and movement of moist air masses into southern Africa from the north-east (Stokes
et al.,
1997
;Stokesetal.,
1998
).
This reconnaissance style of dating was followed by a programme of detailed OSL
dating of linear dunes at Witpan in the south-western Kalahari that showed initial
