Lake Musselshell

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Lake Musselshell
Glacial lakes in Montana.jpg
Map of Montana showing Lake Musselshell.
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Red pog.svg
Lake Musselshell
Location Petroleum, Phillips and Garfield Counties, Montana
Coordinates 47°22′29″N107°56′35″W / 47.374722°N 107.943056°W / 47.374722; -107.943056 Coordinates: 47°22′29″N107°56′35″W / 47.374722°N 107.943056°W / 47.374722; -107.943056
Lake type Glacial lake (former)
Primary inflows Laurentide Ice Sheet
Primary outflows Over the divide to the Yellowstone River or along the face of the Ice sheet.
Basin  countries United States
Max. lengthabout 140 miles (230 km)
Max. width40 miles (64 km)
Surface area varied
Surface elevation315 m (1,033 ft)
References [1]

The basin that held Pleistocene Lake Musselshell is in the lower (north-flowing) reach of the river. It is underlain mostly by highly erodible Cretaceous Colorado shale, Montana group sandstone, siltstone and shale, and Hell Creek sandstone and shale. The bedrock is gently folded and affected by local faults and joints. There is a sequence of nine terraces and more than 100 glacial boulders. The terraces are older than the erratics as the erratics rest on the terraces. [2]

Contents

Glacial stages

Advancing out of Alberta a lobe of the late Wisconsin Laurentide Ice Sheet advanced southeastward into east and central Montana and southwestern Saskatchewan, leaving the Cypress Hills and Boundary Plateau unglaciated. As the Laurentide ice crossed the area of the present day Milk River valley in southern Alberta, it was divided into two lobes by the Sweetgrass Hills, which also remained unglaciated. The western lobe, the Shelby lobe, advanced southward to the Missouri River, in the vicinity of Great Falls, Montana. The lobe that extended east of the Sweetgrass Hills, the Havre lobe, moved in two directions. The Lorna sublobe, advanced across the Missouri River to north of the Highwood Mountains. The Malta sublobe expanded southeastward along the present-day Milk River, bounded to the north by the Boundary Plateau and to the south by the Little Rocky Mountains and the region of the Mussellshell River. [3] The Lake Great Falls provides an approximate date and southern boundary for the maximum advance of the glacial lobes into Montana, impounding the Missouri River, Yellowstone River, and Little Missouri River rivers, each valley forming a glacial lake; i.e., Lake Mussellshell, Lake Circle, Lake Jordan, Lake Lambet, Lake Glendive, and Lake Mikkelson. [3]

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Lake Great Falls

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Shonkin Sag

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Hill 57 is a sandstone-capped hill on the benchland northwest of Great Falls, Montana, United States. The origin of the name is in dispute, but probably derives from an advertisement for "Heinz 57" food products that was created on the hillside in the early 20th century. Hill 57 was home to a small and poverty-stricken community of Cree, Métis, and Ojibwe Native Americans from about the 1880s to the 1960s. Although much reduced in number, some of these landless Native Americans continue to reside on Hill 57. The extreme economic deprivation of Native Americans in the area led to the term "Hill 57" becoming a symbol and "a byword for urban Indian poverty". This community subsequently became the most widely cited example of "landless Indians" in Montana.

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Lake Jordan (Montana)

Lake Jordan was a glacial lake formed during the late Pleistocene along the Jordan River. After the Laurentide Ice Sheet retreated, water melting off the glacier accumulated between the Rocky Mountains and the ice sheet. The lake drained along the front of the ice sheet, eastward towards the Yellowstone River and Glacial Lake Glendive.

Glacial Lake McKenzie

Before the Pleistocene Ice Age, circa two million years before present (YBP), the rivers in North, South Dakota and eastern Montana drained northeast into Canada and then into Hudson Bay. 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 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 and a diversion trench was cut. The modern Missouri River follows this pathway.

Lake Circle

Lake Circle was a glacial lake that formed during the late Pleistocene epoch along the Redwater River in eastern Montana. After the Laurentide Ice Sheet retreated, glacial ice melt accumulated in the basin surrounded by the ridges of the preglacial valley and the retreating glacier. Southwest of Nickwall are the remnants of a broad abandoned valley with long side slopes. The valley runs north from Redwater Creek to the Missouri River. The bottom is poorly drained and about 1 mile (1.6 km) in width. It lies 2,015 to 2,020 feet above the sea level and 40 to 50 feet above the Missouri River bottomland. The upland slopes are extensive, clear and flat. The valleys surrounding it are dissected with V-shaped coulees. The difference between the Redwater valley and those around it reflect stream erosion vs. lake sedimentation. The drift in the valleys, appears to be as left by the glacier in the previously created valleys. Using the dating of lake deposits near Great Falls, Montana, the Havre lobe of the Laurentide Ice Sheet dammed the ancestral Missouri River during the late Wisconsin Glacial Period.

Lake Cut Bank

Lake Cut Bank was a glacial lake formed during the late Pleistocene along the Missouri and Sun Rivers. After the Laurentide Ice Sheet retreated, water melting off the glacier accumulated between the Rocky Mountinas and the ice sheet. The lake drained along the front of the ice sheet, eastward towards the Judith River and the Missouri River.

Lake Chouteau

Lake Chouteau was a glacial lake formed during the late Pleistocene along the Teton River. After the Laurentide Ice Sheet retreated, water melting off the glacier accumulated between the Rocky Mountains and the ice sheet. The lake drained along the front of the ice sheet, eastward towards the Judith River and the Missouri River.

References

  1. Physiography and Glacial Geology of Eastern Montana and Adjacent Areas; William C. Alden; United States Government Printing Office: Washington, D.C.; 1932
  2. Extent and Timing of Laurentide Glacial Lake Musselshell, Central Montana; Nicole Kristina Davis; Montana State University; Bozeman, Montana; July 2004
  3. 1 2 Geologic Framework and Glaciation of the Central Area, 1-1-2006; Christopher L. Hill; Boise State University, Boise, Idaho; 2006

Bibliography

See also