FIELD CLASSIFICATION OF SOILS
Soil are classified based on the structure, geologic origin and topography.
1. Sand Sand is the material which passes through 4.75 mm and retained in 75 micron IS sieve. It is of small rounded or angular particles. It is permeable, self draining, grifty to touch, non plastic, cohesion less, high internal friction and incompressible.
2. Gravel: Gravel is the material and its size varies from 3 to 200mm.
3. Clay: An aggregate of micro scopic and submicroscopic particles derived from the chemical decomposition and disintegration of rock constituents. It is a plastic with a moderate to wide range of water content.
4. Silt: A fine grained soil with little or no plasticity. If shaken in the palm of the hand, a part of saturated inorganic soil expels enough water to make its surface appear glossy.
5. Peat This kind of soil is basically formed by the accumulation of dead and decayed organic matter and found in marshy areas.
6. Loamy Soils: This soils consists of sand, silt and clay to some extent. It is a perfect soil for gardening and weak foundation material,
7. Till It is a glacial deposit of sand, gravel or clay. It is unstratified.
8. Tull: Aggregate of a very small mineral or rock fragments ejected from volcanoes during eruption.
9. Leoss: A wind blown cohesive sediment of size between 0.01 to 0.05 mm.
10. Mart: A term used for comparatively stiff marine calcareous clays
11. Caliche: Gravels, sands, silts and clays cemented by salts such as calcium carbonate due to evaporation and ascending moisture are called “caliche”.
12. Varied clay: It is available in layers of inorganic silt and darker silty clay.
13. Bentonite: Chemically Bentonite is hydrous aluminium silicate contains montmorillonite. It is derived from the decomposition of volcanic ash. It is highly plastic and undergoes large volume changes with change in water content.
