A model of surface water hydrology of the Great Lakes, North America during the past 16,000 years

A model of glacial isostatic adjustment (GIA) is combined with GIS methods to predict the surface water history of the Great Lakes region of North America during the past 16,000 years. The extent of lakes continually changed as the Laurentide ice sheet margin fluctuated and GIA affected the elevations of ice-free outlets. Given only a modern digital elevation model, an earth viscoelastic structure and an ice sheet history, the model adequately represents the Great Lakes history that was developed by glacial geologists during more than a century of field studies. The model predicts the location and elevations of the lowest ice-free outlets and the extent and bathymetry of the proglacial and post-glacial lakes. Results indicate that the Lake Algonquin shoreline, formed about 13,000 years ago, plunges below the present level of Lake Michigan rather than becoming subhorizontal as was once thought leading early geologists to conclude the region was stable and not experiencing GIA. Rather our study indicates that the southern region of the Great Lakes is subsiding, a conclusion reinforced by modern GPS and lake level data. GIA also contributed to many avulsions of river channels during the past 10,000 years as post-glacial tilting promoted stream capture.