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In-Depth Information
with some arguing for considerable regional variability in rainfall during glacial times
(Wang et al.,
2004
;Bushetal.,
2009
; Cruz et al.,
2009
). The pluvial lakes in the arid
Bolivian Altiplano and the wetlands in the piedmont areas of northern Chile have
long aroused curiosity and have been the subject of a sustained program of drilling,
microfossil analysis and dating by U-series and
14
C (Sylvestre,
2009
; Vimeux et al.,
2009
).
5.7 Conclusion
One great advantage of working in deserts is that their very aridity has helped preserve
the evidence of past climatic events, such as river and lake deposits. Aridity has aided
the preservation of former cities such as Uruk in the lower Euphrates Valley, where
clay tablets written some 4,700 years ago have provided us with an epic account of
the activities of Gilgamesh, king of Uruk. Equally well-preserved are the cities of
Harappa and Mohenjo-Daro in the middle Indus and adjacent valleys, inhabited more
than 4,000 years ago and thought by some to have been abandoned because of climatic
change.
The history of desert research in every arid region follows a very different set of
trajectories, depending on local factors and contemporary political, social and eco-
nomic constraints. Military conquest and the lure of gold controlled initial exploration
in South America. Trade determined external links between China, India and Europe
some 2,000 years ago. European colonisation of the Sahara soon gave way to sci-
entific exploration, with attention focussed on former rivers and lakes, followed by
more detailed studies of fossil pollen and diatoms. In North America, exploration
of the Grand Canyon and of the Great Basin lakes provided us with a new set of
geological concepts and provided the foundation for quantitative geomorphology. In
both South and North America, the presence of prehistoric stone tools and of large
extinct animals initiated the ongoing debate as to whether humans or climate change
caused the extinctions.
