What are glacial grooves?

Glacial striations are scratches or gouges cut into bedrock by glacial abrasion.

Glacial striations are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them with moving glaciers. They also noted that if they were visible today that the glaciers must also be receding.[1]