Modelled Topography of North America

Topography as represented by a GCM and RCM. The larger grid boxes in the map illustrate the topography of North America 11,000 years ago in a GCM that has a resolution of about 300 km × 300 km in latitude and longitude. The inset box, which is the domain of the RCM, illustrates topography on 45 km × 45 km grid boxes. The area within the RCM domain includes the Rocky Mountains in the southwest, the greatest heights of the Laurentide Ice Sheet (LIS) in the northeast and the large proglacial Lake Agassiz (blue arrow) along the southwestern margin of the ice sheet as reconstructed from the geologic record. The Great Lakes are located south of the eastern margin of the ice sheet. From Hostetler et al. (2000).