|Title: ||Pans of the southern Kalahari, Botswana|
|Authors: ||Lancaster, Ian Nicholas|
|Issue Date: ||22-Feb-1977|
main geomorphic features of the southern Kalahari in Botswana are
the 1000 pans or small dry lakes which lie along the broad watershed
between the Nossop - Molopo and Makgadikgadi drainages.
No previous detailed studies exist of the pans, which appear to have
developed under climatic conditions unlike those of today, and appear
to represent further evidence for Quaternary climatic change in the
The pans, whioh may have a grassed, partly grassed or bare clay
surface, are contained in shallow sub circular to sub elliptical
isolated depressions, on the southern side of which is an area of
fringing dunes, indicative of a deflation origin for the pan
Analysis of the distribution of the pans shows that they are
strongly clustered but do not form aligned groupings.
Two dune ridges, both formed by northerly winds, are identified.
The composition of the dunes shows that the outer dunes were formed
by deflation from the site of the pan depressions and the inner
dunes by deflation of sandy pan deposits.
The nature of the deposits which underlie the pans and the flanks
of the inner dunes is described, and upper sandy and lower clayey
phases identified. Their composition indicates that the pan
depressions once held extensive permanent lakes, which gradually
contracted as the climate became drier. The nature of the pan
surfaces today is shown to represent a sequence as the pans are
excavated by deflation.
The paleoclimatic significance of the three main periods in the origin
and development of the southern Kalahari pans is discussed. The pan
deposits provide further evidence for a major wet period in the
Kalahari some 12000 to 20000 years ago. Deflation to form the outer
dunes took place in the arid period that occured 20000 to 25000 years
ago, and the inner dunes were formed during dessication of the
climate some 10000 to 12000 years ago.|
|Appears in Collections:||Theses - Department of Geography|
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