| Lake Circle | |
|---|---|
 Map of Montana showing Lake Circle. | |
  Lake Circle | |
| Location | McCone at town of Circle and Dawson County, Montana |
| Coordinates | 47°32′30″N 105°24′36″W / 47.541644°N 105.410087°W |
| Lake type | Glacial lake (former) |
| Primary inflows | Laurentide Ice Sheet |
| Basin countries | United States |
| Max. length | about 1 mile (1.6 km) |
| Max. width | about 45 miles (72 km) |
| Surface area | varied |
| Surface elevation | 2,020 m (6,630 ft) |
| References | [1] |
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 (614 to 616 m) above the sea level and 40 to 50 feet (12 to 15 m) 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.[1] 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.[2]