(a) Define the term mass wasting (b) Describe two types of mass wasting (c) State...

Explanation

(a) Definition - movement of weathered material (debris) under the force of gravity usually down slope

(b) Types;

- Soil creep

- Solifluction

- Landslide, Slumping, etc.

(i) Soil Creep;

• It occurs in areas of deep chemical weathering on moderate slopes.
• It is caused by rain drop impact and thaw and freeze of ice.
• It is also caused by expansion and contraction of soil aggregates.
• It is responsible for down slope tilting of trees on slopes and the movement is slow and not noticeable.

Identifying mass wasting - Description

(ii) Solifluction

• It occurs in temperate and sub-polar regions *Its soil is usually saturated
• Its soil and rock fragments move downslope.
• Freezing and thawing alternate to supply the kinetic energy required for the debris transfer.
• It is frozen creep.
• Movement is not restricted to definite channels.

Identifying mass wasting - Description

(iii) Landslide:

• Various forms such as shrimping, debris fall involves dry mass of earth's debris rock shrimping.
• Movement of large rock debris
• Over underlying weak rock
• Movement is in succession
• Small rock debris moving down slope at a time resulting in a number of step like terracettess, e.g. Mississippi valley.

Identifying mass wasting - Description

(c) Effects

• Loss of farmlands
• Displacement of settlements *Disruption of transportation network
• Tilting of electric poles and telegraph poles
• Damming of a river *Loss of soil fertility