Geography [3 Mark Question Answer]

Soil formation is important for mankind as:

1. A habitat for several plants and animals
2. A storage bank for water and nutrients
3. Foundation of the world’s food chain
4. Provides an anchor for plants

Hydration :
This occurs when water itself chemically combines with some minerals present in rocks. Thus, crystalline minerals, such as feldspar and potash, absorb water and become a powdery mass due to the process of hydration, resulting in their erosion.
Solution :
This is the simplest form of chemical weathering by which some minerals dissolve in water when rainwater falls on rocks or when river water flows over rocks. The soluble minerals dissolve and are removed, . resulting in the breakup of the rocks.

Granular disintegration :
A form of weathering where the grains of a rock become loosened and fall out to leave a pitted and uneven surface.
Exfoliation :
When the surface layers of rounded and boulders gradually peel off in layers due to expansion of the outer layer during the day and the contraction of the same layer during night, the process is called exfoliation.

Soil conservation is very important because soil consists of
mineral particles, moisture, living organisms like bacteria and earthworms, and decayed organic matter. It is one of the most important resources as human beings-depend on it, both directly and indirectly, for their basic needs of food, shelter, and clothing. It takes thousands of years for even a thin layer of soil to form.

Water plays an important role in chemical weathering. The carbon dioxide in atmosphere dissolves in rainwater and form carbonic acid and reacts with minerals in the rocks. The soluble minerals dissolve in water such as feedspar and potash absorb water and become a powdery mass. Similarily soluble minerals dissolve and are removed, resulting in the breakup of the rocks. Rock salt, gypsum, and silica are examples of minerals that are highly soluble and when rainfall falls they decompose.

Gradation is the process of levelling the land by means of moving agents like rivers, or wearing away and lowlands are raised by adding the eroded material by the process of deposition. This is because there is constant earth movement which raises mountains and winds, seas and waves. The highlands are made low by erosion and this process is called degradation and materials are deposited elsewhere in depressions like valleys, lakes, etc. and these lowlands are raised by the process called aggradation.

Controlled grazing is a simple method of soil conservation, It is to restrict the grazing of cattle, sheep and goats on grasslands and within forests. When cattle graze on fields, grass and smaller plants get tom from their roots, leaving the soil loose and exposed to wind and water erosion. Moreover, the pressure of the animals hooves on the soil makes it lose its cohesion and structure, exposing it to the forces of wind and water. Land meant for grazing of cattle should be specially selected and fenced off.

Contour Tilling — In this method the farmer tills or ploughs the fields along the contours of the land rather than tilling up and down the slope. Contour tilling is practised in hilly areas rather than the plains. It prevents the soil from being washed away by water or by surface run-off as the contour acts like a bund. The contour also facilitates the percolation of water into the soil.
Contour Bunding — Soil is conserved by making bunds or walls or embankments made of mud along contour lines to prevent water from draining out of the cultivated field, thereby preventing erosion.

Factors that affect weathering are :

1. Local climate
2. Mineral composition
3. Structure of rock
4. Human activities
5. Amount of exposed or bare rocks surface, and human activities.