Weathering B Physical Weathering 1 Weathering due to increase in void space Expansion and contraction Plant Wedging Thermal Expansion cycles of heating and cooling Unloading Exfoliation mainly granite Wetting and drying Growth of crystals Aveolar Weathering Spalling Spheroidal Weathering Chemical Weathering 2 Causes Mineral instability Exposure air and water Carbonic Acid 3 Common types Solution dissolution Carbonation carbonic acid Most minerals dissolve in water Exceptions Quartz silica Reversible reaction Hard soft water Chemical precipitation Travertine Carbonate calcium or magnesium Limestone Dolostone Hydrolysis Water disassociates into H and OH H replaces cations in minerals Hydroxyl Anion Cation Hydrolysis and roots H from metabolism of living plants Interact with clay colloids in soil Hydration Addition of water molecule outside of mineral Shrink swell clays Vertisols Oxidation and reduction half reactions Oxidation O bonds removal of electrons to minerals to make oxides less chemically stable Reduction O bonds addition of electrons to minerals to make them more chemically stable Iron Oxygen Iron oxide Aluminum Oxide Al oxide Iron Oxygen Iron oxide Aluminum Oxygen Al oxide