Glacial Lake Iroquois
Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago. The lake was essentially an enlargement of the present Lake Ontario that formed because the St. Lawrence River downstream from the lake was blocked by the ice sheet near the present Thousand Islands. The level of the lake was approximately 30 m (~100 ft) above the present level of Lake Ontario.
| Lake Iroquois | |
|---|---|
This map shows the valley of the Mohawk River, through which Glacial Lake Iroquois crossed the mountains to the Hudson River Valley. | |
Lake Iroquois | |
| Location | North America |
| Group | Great Lakes |
| Coordinates | 43.7°N 77.9°W |
| Lake type | former lake |
| Etymology | Iroquois or Haudenosaunee (/ˈhoʊdənoʊˈʃoʊni/; "People of the Longhouse") |
| Primary inflows | Niagara River Welland Canal |
| Primary outflows | Mohawk River to the Hudson River |
| Basin countries | Canada United States |
| Max. length | 196 mi (315 km) |
| Max. width | 57 mi (92 km) |
| Surface elevation | 345 ft (105 m) |
| 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 |
The lake drained to the southeast, through a channel passing near present day Rome, New York. The Rome Sand Plains has several sand ridges that geologists think were formed at this time. The channel then followed the valley of the Mohawk River to the Hudson River.
The lake was fed by Early Lake Erie, as well as Glacial Lake Algonquin, an early partial manifestation of Lake Huron, that drained directly to Lake Iroquois across southern Ontario, along the southern edge of the ice sheet, bypassing Early Lake Erie.
The subsequent melting of the ice dam resulted in a sudden lowering of the lake to its present level, a potential trigger for the Younger Dryas episode.