Abstract
ABSTRACTAlong the margins of continental ice sheets, lakes formed in isostatically depressed basins during glacial retreat. Their shorelines and extent are sensitive to the ice margin and the glacial history of the region. Proglacial lakes, in turn, also impact the glacial isostatic adjustment due to loading, and ice dynamics by posing a marine‐like boundary condition at the ice margin. In this study we present a tool that efficiently identifies lake basins and the corresponding maximum water level for a given ice sheet and topography reconstruction. This algorithm, called the LakeCC model, iteratively checks the whole map for a set of increasing water levels and fills isolated basins until they overflow into the ocean. We apply it to the present‐day Great Lakes and the results show good agreement (∼1−4%) with measured lake volume and depth. We then apply it to two topography reconstructions of North America between the Last Glacial Maximum and the present. The model successfully reconstructs glacial lakes such as Lake Agassiz, Lake McConnell and the predecessors of the Great Lakes. LakeCC can be used to judge the quality of ice sheet reconstructions. © 2019 The Authors Journal of Quaternary Science Published by John Wiley & Sons Ltd.
Highlights
During the retreat of ice sheets, vast amounts of freshwater are released
The largest proglacial lake in North America after the Last Glacial Maximum (LGM) was Lake Agassiz, which formed along the southern margin of the Laurentide Ice Sheet (LIS) (Teller and Leverington, 2004)
The lakes calculated for the different ice sheet reconstructions between the LGM and present day (PD) are presented
Summary
The retreating ice leaves a deeply depressed topography that only slowly recovers due to delayed glacial isostatic adjustment (GIA). In this depressed terrain along the ice margin, meltwater accumulates and forms lakes. These can be the size of an inland sea and impose marine‐like boundary conditions on the ice sheet (Tweed and Carrivick, 2015), which may impact the ice dynamics. The largest proglacial lake in North America after the Last Glacial Maximum (LGM) was Lake Agassiz, which formed along the southern margin of the Laurentide Ice Sheet (LIS) (Teller and Leverington, 2004). Strandlines and lake sediments provide evidence of the extent of these ancient lakes
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