Nipissing Great Lakes
| Nipissing Great Lakes | |
|---|---|
Map of Nipissing Great Lakes from the U.S. Geological Survey monograph of 1915. | |
| Location | North America |
| Group | Great Lakes |
| Coordinates | 45°48′N 84°43′W / 45.8°N 84.72°W |
| Lake type | former lake |
| Primary inflows | Laurentide Ice Sheet |
| Primary outflows | Ottawa River to the Mattawa River |
| Basin countries | Canada United States |
| First flooded | 7,500 years before present |
| Max. length | 241 mi (388 km) |
| Max. width | 200 mi (320 km) to 300 mi (480 km) |
| Max. depth | 595 mi (958 km) to 597 mi (961 km) |
| Surface elevation | 580 mi (930 km) |
| References | United States Geological Survey, George Otis Smith, Director; The Pleistocene of Indiana and Michigan and the History of the Great Lakes; Frank Leverett and Frank B. Taylor; Department of the Interior, Monographs of the United States Geological Survey; Volume LIII; Washington; Government Printing Office; 1915 |
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Nipissing Great Lakes was a prehistoric proglacial lake. Parts of the former lake are now Lake Superior, Lake Huron, Georgian Bay and Lake Michigan. It formed about 7,500 years before present (YBP). The lake occupied the depression left by the Labradorian Glacier. This body of water drained eastward from Georgian Bay to the Ottawa valley. This was a period of isostatic rebound raising the outlet over time, until it opened the outlet through the St. Clair valley, at one stage it had two stable outlets (north and south) both draining to the east.