Australia: The Land Where Time Began

A biography of the Australian continent 

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.

Sources & Further reading

Smith, Mike, 2013, The Archaeology of Australia’s Deserts, Cambridge University Press