abrasion

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Grooves on bedrock are product of abrasion 
by rock embedded in the base of a glacial 
as it moved across the surface

Source: Geological Survey of Canada
Used with permission

Abrasion is the wearing away of the earth surface by agents of erosion, e.g., wind, water, or ice. Abrasion occurs when the agent of erosion uses a "tool" to scrape away at the surface. 

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