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The Keewatin Rockholes

"The Keewatin Rockholes

About 18,000 years ago an extensive sheet of thick continental glacial ice, referred to as the Laurentide Ice Sheet, covered 90 percent of Canada including Lake of the Woods. The erosive action of the glacial ice and meltwater carved and sculpted the bedrock surface of the land and deposited surface materials such as sand and gravel. The Keewatin Rockholes are an example of water sculpted erosional forms left behind by the glacier.

The Rockholes are round rimmed shafts, deeper than they are wide, with internal spiral grooves. The Rockholes were sculpted into the hard bedrock surface by the action of swift jet-like streams of swirling glacial meltwater that carried a considerable amount of gravel and fine sediment. The high velocity, sediment-laden water eroded circular depressions into the rock by abrasion and grinding. The four holes in the rock range in diameter from thirty inches to several feet with the depth range from four to seven feet.

The Keewatin Rockholes provide evidence for glaciation in the Lake of the Woods area and demonstrate that sediment-laden, high velocity water can perform major and unusual feats of erosion."

Submitted by: Mandi Schwarz

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