Glacial striations or glacial grooves are gouges or grooves cut into the bedrock by glacial ice and meltwater as it slowly ground its way along during one of the Earth's Ice Ages or by mountain glaciers. Striations usually occur as multiple, straight parallel lines representing the movement of the sediment loaded base of the glacier. Large amounts of gravel and boulders were carried along underneath the glacier and provided the scouring power to cut these grooves into the bedrock. Fine sediments in the base of the moving glacier scoured and polished the bedrock. They are often helpful in tracking the course and direction of a glacial prescence, acting as a literal roadmap in the underlying bedrock. Among other clues, the depth and erodedness of the gouges are good indicators as to when the glacier "passed through" the area in question and surounding geological conditions.

One very good example can be found at the National Natural Landmark at Glacial Grooves, Kelleys Island, Ohio which is 400 feet long, 15 feet deep and 30 feet wide. A much longer nearby groove on the island, the Great Grooves, was quarryied out in the early 20th century. Those grooves were also about 15 feet deep and 30 feet wide but were 2000 feet long.

In glaciation, a groove called a striation was often gouged out in the bedrock under the ice sheet by rocks frozen in ice.

External links

• Ohio Historical Society

Glaciology

Souvek