Glacial grooves are long, deep scratches or grooves found on rock surfaces, created by the movement of glaciers. As glaciers advance, they carry rocks and debris that scrape against the underlying bedrock, leaving these distinct marks. The patterns and depth of the grooves can provide valuable information about the direction and speed of the glacier's movement. These formations are often found in areas that were once covered by ice during the last Ice Age. One famous example of glacial grooves can be seen on Kelleys Island in Lake Erie, where visitors can observe the impressive evidence of ancient glacial activity.