Before the Pleistocene Ice Age, circa two million years before present (YBP), the rivers in

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

and eastern

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

drained northeast into

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

and then into

Hudson Bay Hudson Bay, sometimes called Hudson's Bay (usually historically), is a large body of Saline water, saltwater in northeastern Canada with a surface area of . It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast o ...

.The Missouri River; John P. Bluemle; North Dakota Geological Survey; Bismarck, North Dakota; 02-Jan-2008 The Keewatin Lobe of the continental ice sheet, block the flow of water northward and impounded it along the ice front. Lakes formed, until the waters could find a new way to drain. Initially, the north flowing rivers followed the front of the glacier eastward and into a valley that passed between

Garrison A garrison is any body of troops stationed in a particular location, originally to guard it. The term now often applies to certain facilities that constitute a military base or fortified military headquarters. A garrison is usually in a city ...

and Riverdale, to the Turtle Lake area, and on into Sheridan County. This is known as the preglacial McClean River. This valley became blocked by the glacier and the glacial lake identified as Lake McKenzie formed. Eventually, water level rose to crest the south ridge a point near Riverdale — at the site of the modern

Garrison Dam Garrison Dam is an earth-fill embankment dam on the Missouri River in central North Dakota, U.S. Constructed by the U.S. Army Corps of Engineers from 1947 to 1953, at over in length, the dam is the fifth-largest earthen dam in the world. The res ...

and a diversion trench was cut. The modern Missouri River follows this pathway.

References

Bibliography

*Alden, W. C., 1958, Physiography And Glacial Geology Of Eastern Montana And Adjacent Areas, U. S. Geological Survey Professional Paper 174. *Colton, R. B., Lemke, R. W., and Lindvall, R. M., 1961, Glacial map of Montana East of the Rocky Mountains, U. S. Geological Survey Miscellaneous Geological Investigations Map I-327. *Howard, A. D., 1958, Drainage Evolution In Northeastern Montana and Northwestern North Dakota, Bulletin of the Geological Society of America, v69, 575-588. *Lemke, R. W., Laird, W. M., Tipton, M. J., and Lindvall, R. M., 1965, Quaternary Geology Of Northern Great Plains, in Wright, H. E., Jr., and Frey, D. G., Eds, The Quaternary of the United States, Princeton University Press, Princeton, NJ. *Lindvall, R. M., 1962, Geology Of The Eagle Buttes Quadrangle, Chouteau County, Montana, U. S. Geological Survey Miscellaneous Geological Investigations Map I-349. *Thornbury, W. D., 1965, Regional Geomorphology Of The United States, John Wiley & Sons, Inc., New York. *Trimble, D. E., 1980, The Geologic Story Of The Great Plains, Geological Survey Bulletin 1493. *Wayne, W. J., Aber, J. S., Agard, S. S., Bergantino, R. N., Bluemle, J. P., Coates, D. A., Cooley, M. E., Madole, R. F., Martin, J. E., Mears, B., Jr., Morrison, R. B., and Sutherland, W. M., 1991, Quaternary Geology Of The Northern Great Plains, in The Geology of North America, Vol K-2, Quaternary Nonglacial Geology: Conterminous U. S., The Geological Society of America. {{Pleistocene Lakes and Seas Former lakes of the United States Geology of North Dakota Glacial lakes of the United States Natural history of North Dakota Proglacial lakes

See also

References

Bibliography