QUATERNARY PALAEOLAKES IN THE EVOLUTION OF SEMIDESERT BASINS, WITH SPECIAL EMPHASIS ON LAKE BONNEVILLE AND THE GREAT-BASIN, USA

This paper reviews attributes of Quaternary lakes and lake basins which are often important in the environmental prehistory of semideserts. Basin-floor and basin-closure morphometry have set limits on palaeolake sizes; lake morphometry and basin drainage patterns have influenced lacustrine processes; and water and sediment loads have influenced basin neotectonics. Information regarding inundated, runoff-producing, and extra-basin spatial domains is acquired directly from the palaeolake record, including the littoral morphostratigraphic record, and indirectly by reconstruction. Increasingly detailed hypotheses regarding Lake Bonneville, the largest late Pleistocene palaeolake in the Great Basin, are subjects for further testing and refinement. Oscillating transgression of Lake Bonneville began about 28 ka, the highest stage occurred about 15 ka, and termination occurred abruptly about 13 ka. A final resurgence of perennial lakes probably occurred in many subbasins of the Great Basin between 11 and 10 ka, when the highest stage of Great Salt Lake (successor to Lake Bonneville) developed the Gilbert shoreline - and when the Russell shoreline formed 500-600 km away, in the Carson Desert of the Lake Lahontan basin. The highest post-Gilbert stage of Great Salt Lake, which has been one of the few permanent lakes in the Great Basin during Holocene time, probably occurred between 3 and 2 ka. A set of eighteen general observations regarding geologic aspects of the palaeolake record in semidesert basins is helping to guide Quaternary studies in the Great Basin. © 1990.