Title Bar: Illustrated Glossary of Alpine Glacial 
	  Landforms | Home   | Glossary   | Exercise |


    Erosional Landforms
    Giant stair steps
    Glacial trough
    Hanging valley
    Paternoster lakes
    U-shaped valley

    Depositional Landforms
    End moraine
    Ground moraine
    Lateral moraine
    Medial moraine

    Ice Features
    Cirque glacier
    Valley glacier
    Ice fall

An elongate depression carved out of bedrock as numerous rock particles embedded in the base of a glacier scour away the underlying bedrock. As a mineral, ice is not very hard and as ice flows over underlying bedrock, the ice is incapable of eroding the bedrock. When rocks freeze onto the base of a glacier, however, these rocks may be sufficiently hard that as the ice flows across underlying bedrock, the rock particles frozen on the base of the glacier may erode the underlying rock, which is how grooves form.

Photo: glacial grooves

Photo: K.A. Lemke. Used with permission.

Topographic map: grooves

The grooves in this photo are currently filled with water forming elongate lakes. Sperry Glacier carved out these grooves when the glacier was larger than it is today. The photo was taken where the camera is located on the topographic map. In this photo, you are looking toward the northwest. Just past the end of the grooves you can see some sandy-looking hills or mounds in the photo. These are part of an end moraine. Off in the distance, you see some mountain peaks in the photo. These peaks are off the section of topographic map shown here. Sperry Glacier, which shows on the map, is out of the photo off to the lower right.

On the topographic map, north is toward the top of the map. Sperry Glacier is shown in white with blue contour lines and a dashed blue line marks the border of the glacier. Some of the lakes in the photo appear on the map in blue. The grooves not containing water are shown by the bends in the contour lines just beyond (northwest of) the edge of the glacier. In order to see the falls labeled on the map and Avalanche Lake at the base of the falls, you would have to walk out to the end moraines, over the top of the moraines, and then you could see the steep drop-off where the falls are located.

| More Examples of Grooves |

| Home | Glossary | Exercise |

| Virtual Geography Department Project | Physical Geography Working Group |
All commercial rights reserved. Copyright 2010 by Karen A. Lemke. Earlier copyright 2002 by Karen A. Lemke, and 1998 by Karen A. Lemke and Linda Freeman.
Last updated June 2010 KAL.