Regional Soil Deposits In India
In the previous article, we read about different types of soils by their name. In this article now, we will be going to study the different soil deposits present in regional India.
Soil deposits in India can be classified in the following in the five major groups:
- Alluvial deposits are found in northern India. The thickness of the alluvial deposit in the Indo-Gangetic and Brahmaputra floodplains varies from a few meters to more than one hundred meters.
- Alluvial deposits also occur at some places in peninsular India.
- The alternate layers of sand, silt, and clay are found in the alluvial deposits.
- The thickness of each layer depends upon the local terrain and the nature of floods in the rivers which causing deposition.
- The density of the alluvial deposits is generally low.
- These deposits are liable to liquefaction in earthquake-prone areas.
Black Cotton Soils
- The black cotton soil is found in central India as well as in some part of Southern India.
- These deposits are of residual soil and formed from basalt or trap rocks.
- These soils are suitable for growing cotton and hence called as Black cotton soil.
- The black cotton soil is clay of high plasticity. They contain the clay mineral montmorillonite.
- These soils have high shrinkage and swelling characteristics, however, shearing strength is very low.
- The soils are highly compressible and have a very low bearing capacity.
- Lateritic deposits are formed by decomposition of rocks, removal of bases and silica, and accumulation of Iron oxide and Aluminium oxide.
- The presence of Iron oxide imparts reddish or pink color to the soil.
- Lateritic soils are residual soils formed from basalt.
- These deposits are found in central, southern and eastern India.
- These soil are very soft and can be cut with a knife in wet condition, however, soil hardens as it becomes dry with the passage of time.
- The plasticity of these soil decreases when we dig deeper and deeper.
- These soils have relatively high specific gravity.
- A large part of Rajasthan and adjoining states is covered with sand dunes. These deposits are found in arid condition area with practically very little rainfall.
- Dune sand is uniformly-graded. The size of the particles is in the range of fine sand.
- The sand is non-plastic and highly pervious.
- The sand is usually found in loose condition.
- Marine deposits are mainly confined along a narrow belt near the coast.
- In the south-west coast of India, there are thick layers of sand above deep deposits of marine clays.
- The marine deposits have very low shearing strength and are highly compressible.
- The marine clays are soft and highly plastic.
- They contain a large amount of organic matter.