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Soil
Soil
Soil is composed of three layersis composed of three layersis composed of three layers
The uppermost layer of soil is called the topsoil . It is dark in colour as it is rich
in humus . It is the most fertile layer. Humus is formed by the dead and
decaying parts of plants and animals. Just below the topsoil is a light coloured
layer called the subsoil . It contains less humus. Below the subsoil, there is a

layer of lumps of parent rock. Below this is non-porous, unweathered bedrock .

SOIL EROSION
Soil erosion takes place when the uppermost

layer of the soil gets carried away by natural
agents like wind, rains and floods. This carrying

away of the topsoil from one place to another
by natural agents is called soil erosion.
Deforestation is the major cause of soil

erosion. When the fertile topsoil is eroded, the
less fertile subsoil comes to the surface which

leads to a fall in crop production. Gradually, the
land loses its fertility and becomes barren.

Activities like deforestation and overgrazing by
animals also contribute towards soil erosion.

Erosion by Windby Windby Wind Suspension
Erosion
Erosion
Suspension
Suspension
Topsoil is easily carried away by strong
Wind
Wind
Wind
winds. Erosion due to wind is the greatest
Saltation
in areas where there is less vegetation. Saltation Saltation
Saltation
Saltation
Saltation
Creep
Creep
Creep
Plantation restricts soil erosion by wind.
Erosion
Erosion
Erosion by Waterby Waterby Water
Heavy rain or running water washes away the topsoil causing soil erosion.
Heavy soil erosion occurs in hilly areas because river water flows faster on the
slopes and washes away the fertile soil.
On reaching the plains, the river slows down its
Dense
crops
flow and the soil thus carried is deposited at the
bottom of the river. This is called silting . If the

Soil erosion in the hilly areas continues for a longer
cover
time, the amount of soil-spread in the plains
Sheet
wash
Fertise
Fertise
Fertise over the years will be huge. This can make the
river change its course.
Soil Erosion by water
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