Five major influences on soil formation include the nature of the original parent material, weathering, climate, land surface features, and the action of plants and animals. These factors determine the physical and chemical properties of various kinds of soil. Parent material is the basic mineral and organic material from which the soil is formed. Alluvial materials are deposited by rivers and provide rich productive deltas, floodplains, and terraces. Lacustrine deposits, formed in lakes, were later exposed by receding glaciers.
Marine deposits occur along the margins of most oceans and gulfs.
During the last Ice Age, huge continental ice sheets moved across much of Northern Europe, Asia, and North America. Their enormous weight crushed and transported material that later served as parent material for soil. The residual parent material from which soil is formed is loose, slightly weathered rock called regolith. Residual formations settle in layers that range from fully weathered material at the top to unchanged parent material at the bottom. Organic parent material occurs when organic deposits accumulate in wet or cool regions.