Admiralty Lake was a

proglacial lake In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ...

in the basin of what is now

Lake Ontario Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York. The Canada–United States border sp ...

. The shoreline of Admiralty Lake was about lower than Lake Ontario. The shoreline of

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 down ...

, an earlier proglacial lake, was much higher than Lake Ontario's, because a lobe of the

Laurentian Glacier The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years a ...

blocked what is now the valley of the

St Lawrence River The St. Lawrence River (french: Fleuve Saint-Laurent, ) is a large river in the middle latitudes of North America. Its headwaters begin flowing from Lake Ontario in a (roughly) northeasterly direction, into the Gulf of St. Lawrence, connecting ...

. Lake Iroquois drained over the

Niagara Escarpment The Niagara Escarpment is a long escarpment, or cuesta, in Canada and the United States that runs predominantly east–west from New York through Ontario, Michigan, Wisconsin, and into Illinois. The escarpment is most famous as the cliff over ...

, and down the

Mohawk River The Mohawk River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed October 3, 2011 river in the U.S. state of New York. It is the largest tributary of the Hudson River. The Mohawk f ...

. When the lobe of the glacier retreated the weight of the glacier kept the outlet of the St Lawrence River lower than the current level. As the glacier continued to retreat the region of the

Thousand Islands The Thousand Islands (french: Mille-Îles) constitute a North American archipelago of 1,864 islands that straddles the Canada–US border in the Saint Lawrence River as it emerges from the northeast corner of Lake Ontario. They stretch for abo ...

rebounded, and the lake filled to its current level.

References

Bibliography

*"Nearshore Geology". Aquatichabitat.ca. Archived from the original on 2012-01-27. *J Terasmae, E Mirynech (1964). "Postglacial chronology and the origin of deep lake basins in Prince Edward County, Ontario". Conference on Great Lakes Research, 1964 - International Association for Great Lakes Research. {{DEFAULTSORT:Admiralty Lake Proglacial lakes Geology of New York (state) Glacial lakes of Canada