Soil is formed from the physical and chemical weathering of rocks-processes described historically becau'se they involve eons of time-by glaciation and by wind and water transport of soil materials, which are later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic-always changing as a result of the forces of nature and particularly by the influences of man. Soil has been studied as long as history has been documented. Numerous references to soil...