SS2 First Term Geography Lesson Note – Glacial Action

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WEEK 5                                                                  

TOPIC:   GLACIAL ACTION

CONTENT:  

(1) Action of glacial in temperate region

(2) Features of glacial erosion in the highland areas

(3) Glacier erosion in lowland 

(4) Economic importance of Glacier Features

SUB-TOPIC 1: ACTION OF GLACIER IN TEMPERATE REGION

Action of glacier is an important agent of erosion, here, transportation and deposition of materials is confined to mountains and temperate regions of the wind.

TERMS ASSOCIATED WITH GLACIERS

1. ICE: This refers to the solid form of water, formed as a result of freezing when the temperature is continually below 0⁰
2. GLACIER (moving ice): This implies very large accumulation of ice, (either a frozen sea or river) in motion.

• GLACIATION: This is referring to the wearing away of the earth surface by large accumulation of ice in motion (glacier).

1. SNOW: This is frozen water vapour which falls in form of crystal through the atmosphere.
2. SNOW LINE: This implies the lower limit of perpetual snow cover on the mountain.
3. SNOW FIELD: This is the region that is permanently under snow cover.

It is important to note that Glaciations generally gives rise to erosional features in the highland and depositional features on the lowlands.

ACTION OF GLACIER EROSION

1. SAPPING: Sapping is the breaking up of rocks of alternate freezing and thawing of water at the bottom of cracks between a mass of ice and the sides and floor of a valley or the sides of a mountain.
2. PLUCKING: By plucking, the glacier freezes the joints and beds of the underlying rocks tears out individual blocks and drags them away.
3. ABRASION: By this, the glacier scratches, scrapes, polishes and scours the valley floor with the debris frozen into it. These fragmented debris are powerful tools of erosion (denudation).

EVALUATION

1. Highlight the various terms associated with glacier.
2. Mention three actions of glacier erosion.
3. Discuss two of the actions mentioned in 2 above.

SUB-TOPIC 2: CHARACTERISTIC FEATURES OF GLACIER EROSION IN   THE HIGHLAND

1. STRAITION: Striations are scratches left on rocks over which glacier passes. The rock fragment (of different shapes and sizes) embedded in the glacier affects striation of rocks.
2. CORRIES OR CIRQUE: This is a deep and rounded hollow or depression with steep side form as a result of the downside movement of a glacier from it snow cover valley head, and

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