Soil and its Formation

Soil and its FormationRoman Poudyal

Department of Civil and Environmental EngineeringOklahoma State University

OutlineWhat is soil?

How it form?

Definition of SoilIn generalUpper layer of mantle that may be dug or plowed and which serves as a natural medium for the growth of plantsIn EngineeringUpper layer of mantle is termed as top soilUnconsolidated material, composed of solid particles and void spacesVoid space may contain air, water or both

Soil FormationFormed from weathering of rock and minerals

Long period of time (800 to 1000 years or more) is required

Weathering:Physical weathering processChemical weathering process

Physical WeatheringPhysical processes breaks down the rocksFreezing and thawing

Temperature changes (Cracks)

Chemical WeatheringChemical reactions between rock mineral and different elements

Chemical reactions

Soil Formation (cont.)Weathered particle starts to deposit at same place or at new transported location

Deposition starts to mix with other organic matter

Over period of time layer of soils starts to form

Thank You!!Questions??