Glacial Lake Wisconsin
Encyclopedia
Glacial Lake Wisconsin was a prehistoric proglacial lake
that existed from approximately 19,000 to 15,000 years ago, at the end of the last ice age
, in the central part of present-day Wisconsin
in the United States
.
Glacial Lake Wisconsin was formed by meltwater flowing from glaciers that covered the northern and eastern portions of Wisconsin. The lake was bounded by an ice sheet of the Green Bay Lobe on the east, and by higher topography on its other margins. At its maximum stage, the lake was approximately the same size as the Great Salt Lake
in Utah
, and up to 150 ft (45 m) deep.
The eventual sudden bursting of an ice dam left by the retreating glaciers caused a catastrophic flood
that formed the Dells of the Wisconsin River
in pre-existing Cambrian
sandstone
on the south edge of the lake. The resulting flood lowered the level of the lake to approximately 50 ft (15 m).
Eventually, the Wisconsin River
flowed through its grand canyon to its mouth at the Upper Mississippi River
.
Proglacial lake
In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice...
that existed from approximately 19,000 to 15,000 years ago, at the end of the last ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
, in the central part of present-day Wisconsin
Wisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Glacial Lake Wisconsin was formed by meltwater flowing from glaciers that covered the northern and eastern portions of Wisconsin. The lake was bounded by an ice sheet of the Green Bay Lobe on the east, and by higher topography on its other margins. At its maximum stage, the lake was approximately the same size as the Great Salt Lake
Great Salt Lake
The Great Salt Lake, located in the northern part of the U.S. state of Utah, is the largest salt water lake in the western hemisphere, the fourth-largest terminal lake in the world. In an average year the lake covers an area of around , but the lake's size fluctuates substantially due to its...
in Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, and up to 150 ft (45 m) deep.
The eventual sudden bursting of an ice dam left by the retreating glaciers caused a catastrophic flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
that formed the Dells of the Wisconsin River
Dells of the Wisconsin River
thumb|250px|Dells of the Wisconsin RiverThe Dells of the Wisconsin River — also called the Wisconsin Dells — is a 5-mile gorge on the Wisconsin River in southern Wisconsin, USA...
in pre-existing Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
on the south edge of the lake. The resulting flood lowered the level of the lake to approximately 50 ft (15 m).
Eventually, the Wisconsin River
Wisconsin River
-External links:* * * , Wisconsin Historical Society* * * *...
flowed through its grand canyon to its mouth at the Upper Mississippi River
Upper Mississippi River
The Upper Mississippi River is the portion of the Mississippi River upstream of Cairo, Illinois, United States. From the headwaters at Lake Itasca, Minnesota, the river flows approximately 2000 kilometers to Cairo, where it is joined by the Ohio River to form the Lower Mississippi...
.