GSCI 1051 Lecture Notes - Lecture 11: Soil Horizon, Humus, Clastic Rock
Document Summary
Results of weathering are sediments: clastic- broken rock fragment, biogenic- fragments of dead organisms. Can be clastic or chemical: chemical precipitates deposited when water evaporates. Sediments are transported by gravity, water, wind, or ice to their pace of deposition is called erosion. Windborne sediments move differently: suspension- tiny particles float in water or air, saltation medium particles bounce on the bottom, creep- large ones move slowly by impact. Well sorted sediment forms as fluid winnows away grain. Sediments deposited in basins like flood plains, deltas, lakes, the ocean, deserts, etc. Weathered rocks or sediments mixed with organics and that can support the growth of plants are soil. Organisms physically move rocks and sediment and when they die they leave carbon that forms humus. Soil forming processes operate at different depths and soils develop layers called horizons arranged vertically as a soil profile.
