Image: Glacial Grooves State Park, Kelleys Island OH

Description: Glacial grooves in Columbus Limestone (lower Middle Devonian) at Glacial Grooves State Park, northwestern Kelleys’ Island, western Lake Erie, USA. These spectacular, world-class glacial grooves were carved out during the Pleistocene (the last Ice Age). Glaciers are rivers of ice. Ice is a mineral (H2O). Glacial ice is a rock (technically, a metamorphic rock). Despite being solid, ice does flow under certain conditions at the Earth’s surface. Occasionally, Earth experiences Ice Ages, during which extensive ice sheets cover and move over significant portions of the Earth’s surface. As ice moves over landmasses, it erodes underlying rocks and picks up small to large pieces of debris. This debris accumulates at the base of the ice sheet and scrapes bedrock as the glacier moves, resulting in glacial scratches (glacial striations) (= thin scratch lines on rock) and glacial grooves (= large channels incised in rock).
Title: Glacial Grooves State Park, Kelleys Island OH
Credit: Glacial grooves from Pleistocene glaciation on Columbus Limestone (Middle Devonian) (Glacial Grooves State Park, northwestern Kelleys Island, far-northern Ohio, western Lake Erie, USA) 4
Author: James St. John
Usage Terms: Creative Commons Attribution 2.0
License: CC BY 2.0
License Link: http://creativecommons.org/licenses/by/2.0
Attribution Required?: Yes