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Australia: The Land Where Time Began |
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The Last Interglacial – Lakes and
saltlakes According to Smith in Quaternary research one of
the paradoxes is that the history of deserts is often a history of lakes
and rivers. The sedimentary record of the arid and semi-arid zones in
Australia has been the cornerstone of research of the Late Quaternary in
these regions. The records that are best-developed are those from Lake
Eyre, Lake Frome and the Willandra Lakes, though Lake Amadeus and Lake
Lewis in Central Australia, and on the northern desert margin, Lake
Gregory and Lake Woods. A key to understanding variability in these lake
basins and their differential response to shifts in climate have been
provided by the ‘hydrological threshold’ (Bowler, 1981). Catchment size,
relative to lake area, and the hydrologic balance between inflow and
evaporation control lakes in closed basins. Dotted across Central and
Western Australia, most of the large saltlakes have small catchments
relative to their surface area and it is believed they probably didn’t
function as palaeolakes during the Late Quaternary. These have mostly
remained as playas that are controlled by groundwater processes,
possibly for 70 ka. Lakes that have the ‘amplification’ of large
catchments, in contrast, are particularly sensitive to climatic changes;
with precipitation and evaporation changes that are relatively small,
they are capable of changing from lake basins that are dry to ephemeral
or permanent palaeolakes. Amplifier lakes are not common in the desert,
the main examples being Lake Eyre and lake Lewis and lakes on the desert
margins that are fed by external catchments outside the arid zone, such
as the Willandra Lakes, Lake Gregory and Lake Woods. Smith, Mike, 2013,
The Archaeology of Australia’s
Deserts, Cambridge University Press
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |