Parent material

Parent material is the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form. Soils typically inherit a great deal of structure and minerals from their parent material, and, as such, are often classified based upon their contents of consolidated or unconsolidated mineral material that has undergone some degree of physical or chemical weathering and the mode by which the materials were most recently transported. Parent material is the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form. Soils typically inherit a great deal of structure and minerals from their parent material, and, as such, are often classified based upon their contents of consolidated or unconsolidated mineral material that has undergone some degree of physical or chemical weathering and the mode by which the materials were most recently transported. Parent materials that are predominantly composed of consolidated rock are termed residual parent material. The consolidated rocks consist of igneous, sedimentary, and metamorphic rock, etc. Soil developed in residual parent material is that which forms in consolidated geologic material. Parent material is classified by its last means of transport. Material that was transported to a location by glacier, then deposited elsewhere by streams, is classified as stream-transported parent material, or glacial fluvial parent material. Glacial till is material dragged with a moving ice sheet. Because it is not transported with liquid water, the material is not sorted by size.