Glacial and Postglacial Geologic History of Isle Royale National Park, Michigan: Contributions to the Geology of Isle Royale National Park
Huber NK. 1971. Glacial and Postglacial Geologic History of Isle Royale National Park, Michigan: Contributions to the Geology of Isle Royale National Park. U.S. Geological Survey (USGS) Professional Paper. 754-A. Washington, DC
Isle Royale was overridden by glacial ice during each of the four major glaciations of the Pleistocene Epoch. Because of the northerly location of Isle Royale, each successive glaciation essentially obliterated all direct evidence of preceding glaciations on the island. In the waning phase of the last major glaciation, the Wisconsin Glaciation, the frontal ice margin retreated northward from at least the greater part of the Lake Superior basin, then readvanced into the basin during Valders time. It is to the Valders ice that we can attribute the final aspect of glaciation on Isle Royale, including both erosional and depositional features. It is impossible to estimate the quantity of earlier glacial debris or other surficial materials that might have been present on Isle Royale prior to the Valders readvance, but the readvancing ice appears to have removed most of what might have been present, as judged by the thinness of surficial cover on the eastern two-thirds of the island today. As the Valders ice itself retreated northward, a series of lakes formed in the Lake Superior basin in front of the retreating ice margin. The map shows areas with extensive glacial debris; ice-margin deposits; glacial striation; drumlin; and abandoned shorelines.
- Type
- Published Report
- Authors
- Huber, Norman
- Date of Issue
- 1971-10
- Units
- HIST , ISRO
- Keywords
- ehistory, Geology, Geomorphology, Glaciation, History, Map, Physical Sciences