Summary
The Keewatin ice sheet was a major ice sheet that periodically covered large parts of North America during glacial periods over the last ~2.6 million years. This included the following areas:
- Eastern Montana
- North Dakota
- Eastern South Dakota
- Western Minnesota
- Alberta
- Saskatchewan
- Manitoba
| Keewatin Ice sheet | |
|---|---|
| Type | continental |
| Location | Canadian Shield |
| Area | 2,500,000 km2 (970,000 sq mi)[2] |
| Length | ca 1,460 mi (2,350 km) |
| Highest elevation | Keewatin Dome: 3,200 metres (10,500 ft) above sea level[3] |
| Lowest elevation | Sea level |
| Terminus | North – Arctic Ocean East – Labrador ice sheet South – 40 degrees north latitude West – Rocky Mountains |
| Status | gone |
Centered on the Kivalliq Region, Nunavut, Canada (known as the Keewatin Region, Northwest Territories, until 1999) (ca 102 W, 63 N) the ice sheet covered up to 2,500,000 km2 (970,000 sq mi) the Last Glacial Maximum. At its greatest reach, (14*146=2044 N-S by 12*146=1752 E-W) the northern edge abutted the Greenland ice sheet in Baffin Bay. Running south, along the shore of Baffin Island the edges floated in the Davis Strait. Curling across the southern tip of Baffin Island, entering Hudson Bay, it merged with the Labradorean Ice Sheet, and formed the center of an ice sheet spanning North America from the North Atlantic to the North Pacific oceans.[2] The seam between the two ice sheets passed over the northern tip of the Ungava Peninsula passing south across Hudson Bay and on to the Ontario shore near Fort Stevens. This seam continued southward across Lake Superior, east of the Keweenaw Peninsula of Michigan. It went southward into Wisconsin along the Lake Michigan shoreline and crossed into western Illinois. Reaching down the Mississippi River valley to its junction with the Missouri River, it reaches its most southern point.[2] At this point, the ice sheet no longer abuts the Labradoran ice sheet. The leading edge of the ice sheet follows roughly the Missouri River Valley through Missouri, Kansas, Nebraska and into the Dakotas, reach westward across the Montana, where after (10*146=1,460 mi) it reaches the Rocky Mountains just south of the U.S. and Canadian border and the Cordilleran ice sheet.[2]
The Cordilleran ice sheet forms the western boundary of the Keewatin ice sheet, where they abut along the front of the Canadian Rockies, ending in the Arctic Ocean near the mouth of the MacKenzie River. This northern ice front, floats just off the coast of the Queen Elizabeth Islands, where it completes its border in Baffin Bay and the seam with the Greenland ice sheet.[2]
See also edit
References edit
- ^ Fulton, R. J. & Prest, V. K. (1987). Introduction: The Laurentide Ice Sheet and its Significance. Géographie physique et Quaternaire, 41 (2), 181–186
- ^ a b c d e John P. Bluemle; Guide to the Geology of South-Central North Dakota; Burleigh, Dickey, Emmons, Kidder, LaMoure, Logan, McIntosh, and Stutsman Counties; Educational Series 6; North Dakota Geological Survey, E. A. Noble, State Geologist; Bismarck, North Dakota; revised 1975
- ^ Lacelle, D., Fisher, D.A., Coulombe, S. et al. Buried remnants of the Laurentide Ice Sheet and connections to its surface elevation. Sci Rep 8, 13286 (2018). https://doi.org/10.1038/s41598-018-31166-2 Received: 31 May 2018Accepted: 13 August 2018Published: 05 September 2018; DOI: https://doi.org/10.1038/s41598-018-31166-2
Bibliography edit
- Fred. H. H. Calhoun Sr.; The Montana Lobe of the Keewatin Ice Sheet; Professional Paper No 50 Series B, Descriptive Geology, 79; Department of the Interior, United States Geological Survey, Charles D. Walcott, Director; Washington, D.C.; Government Printing Office; 1906