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 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. This parent material is loosely arranged, particles are not cemented together, and not stratified. This parent material is classified by its last means of transport. For example, 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. The material dragged with a moving ice sheet. Because it is not transported with liquid water, the material is not sorted by size. There are two kinds of glacial till: Basal till - carried at the base of the glacier and laid underneath it. This till is typically very compacted and does not allow for quick water infiltration. Ablation till - carried on or in the glacier and is laid down as the glacier melts. This till is typically less compacted than basal till. Parent material that is created from the sediments coming into lakes that come from glaciers. The lakes are typically ice margin lakes or other types formed from glacial erosion or deposition. The bedload of the rivers, containing the larger rocks and stones is deposited near the lake edge, while the suspended sediments are settle out all over the lake bed. Consist of boulders, gravel, sand, silt and clay from ice sheets or glaciers.