Soil is material capable of supporting plant life. Soil forms through a variety of soil formation processes, and includes weathered rocks through erosion and chemical weathering, combined with dead and living organic matter and air. Soils are vital to all life on Earth because they support the growth of plants, which supply food and oxygen and absorb carbon dioxide and nitrogen.   Soils are classified into "layers" or horizons. The "A" horizon, the one beginning at the surface, is dark colored, root bearing and is high in humus content. The "B" horizon is located beneath the "A" horizon and is more light colored, coarse, granular and low in humus content. The "C" horizon is beneath the "B" horizon and is composed or regolith (The layer of loose incoherent rock material, made up from volcanic ash, glacial drift, alluvium, windblown deposits, organic accumulations, and soils.) And last, the "D" horizon is comprised of bedrock. Primary Soil Properties include: Porosity & Permeability Shear strength Compaction characteristics Soil drainage characteristics Shrink, swell characteristics Plasticity Grain size Reactivity Depth to the water table Depth to bedrock Topography

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