Glacial Action SS2 Geography Lesson Note

The action of glaciers is an important agent of erosion, transportation and deposition in temperate regions or mountainous regions.

TERMS ASSOCIATED WITH GLACIER

1. Ice: This is a solid form of water which results from freezing when the temperature is below 00C.
2. Snow: This refers to frozen water vapour that falls in the form of crystals from the atmosphere. 
3. Snow-Line: It is the lower limit of snow cover on a mountain.
4. Glacier: This means moving ice i.e. large accumulation of ice in motion.
5. Glaciation: It is the wearing away of the earth’s surface by glaciers.
6. Snow Field: This is the region or area that is permanently covered by snow

ACTION OF GLACIER EROSION

1. Sapping: This is the breaking up of rock by alternate freezing and thawing of water at the bottom of cracks.
2. Plucking: It is the tearing away of rocks which have become frozen on the side or bottom of a glacier.
3. Abrasion: This is the wearing away of rocks beneath a glacier by the scouring action of the rocks embedded in the glacier.

FEATURES OF GLACIER DEPOSITION IN LOWLAND AREAS

1. Boulder Clay: This consists of stones of various sizes in a mass of sand and clay.
2. Erratics: These are transported rock fragments which are composed of materials entirely different from the bedrock of the region where they are deposited. They are deposited when the ice carrying them melts into water.
3. Drumlins: It is composed mainly of boulder clay.
4. Eskers: These are long narrow ridges of sand and gravel deposited by melting water. They are usually porous.
5. Terminal Moraines: They are made up of boulders which are deposited at the edge of the ice sheet.
6. Outwash Plain: This is a large area consisting of sand and gravel that are washed down the mountainous zone and deposited to form an outwash plain which lies beyond the terminal moraine