Soil has various meanings depending upon the professional field in which it is being studied.
For engineering purposes, Soil may be define as:
Natural aggregate of mineral grains, loose or moderately cohesive, inorganic or organic in nature.
If we are studying geology, then:
Soil is defined as disintegrated rock.
If we are studying agriculture, then
Soil is the loose mantle at the surface of the earth which helps the growth of the plant.
Residual soil definition
The soil obtained due to weathering may be residual or transported soil. Residual soil definition is:
Soils formed by the weathering of rocks, but located at the place of origin are called residual soils.
Residual soils are formed by the weathering of rocks like granite, basalt, sandstone, lime stone and salts.
Granite is a very hard natural igneous rock. Crystalline texture is visible on it. It is formed essentially of quartz and orthoclase or microcline. It is used specially for buildings and monuments.
Basalt is a dark grey to black rock. It is a igneous rock that consists of basic plagioclase, augite and usually magnetite.
Sandstone is a sedimentary rock. It consists of usually quartz sand united by some silica or calcium carbonate. It is formed by the grains of sand stuck together.
Limestone is a rock that is formed mainly by the accumulation of organic remains such as shells or corals. It consists mainly of calcium carbonate. It is extensively used in building. It yields lime when burned.