It should be emphasized that all mechanisms of glacial erosion may operate in close association or may alternate through time at a particular site. Glacial polish on granite surface, island of Bornholm, Denmark. Subglacial grinding produced this polished surface. Giant glacial groove on Kelleys Island, Ohio. Many giant grooves were once present on Kelleys Island.
Photo shows about half of a preserved groove.
Glacial grooves on Kelleys Island are cut into Paleozoic dolostone. This view depicts intricate striations and small grooves within the main channel. Crescentic gouges on Sioux Quartzite, southwestern Minnesota. Such gouges are produced by ice pressing and dragging a boulder over the bedrock surface. Crescentic gouges, shallow grooves and striations on Sioux Quartzite, southwestern Minnesota.