GEO 320 Study Guide - Final Guide: Soil Horizon, J Harlen Bretz, Clay Minerals
Document Summary
Describe how physical, chemical, and biological weathering differ. Though physical, chemical, and biological weathering are different they are complementary and often strongly influence each other. Biological weathering is when organisms (bioturbation from animals or tree roots) speed up mineral weathering by mechanically breaking down rocks and catalyzing chemical reactions, causing changes in environmental conditions such as soil ph. Chemical weathering dominates in hot, wet climates, and physical weathering dominates in the cold, dry climates. Physical weathering is when rocks break apart into smaller pieces without changing the composition. Chemical weathering is the breaking of chemical bonds metallic, ionic, and covalent. Because many rocks are dominated by a mix of ionic and covalent bonds, solution and acid attack are major weathering processes. Chemical weathering occurs because the minerals and rocks form in equilibrium with deep earth conditions - high pressure, high temperature, and low oxygenation - quite different from the conditions on the surface of the earth.
