Earth Sciences 1022A/B Lecture 5: Earth Sciences 1022A – Lecture 5 – Weathering and Soils

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1022A/B
• Professor: Stephen R Hicock

Document Summary

Earth sciences 1022a lecture 5 weathering and soils. Two main types of weathering: mechanical and chemical (both happen at the same time) Breaking up solid rock to smaller and smaller particles. Reduction of rocks to smaller pieces, includes: Frost wedging: water freezes in rock fractures and expands 9%, prying rock apart o. Happens because water gets into fractures normally in polar areas or high in the mountains. Sheeting: rock surface expands after stuff on top is removed, slabs break off. There is a pressure release after erosion of overlying rocks. Biologic activity: plant roots grow in rock fractures and pry the fractures open. Transforms minerals in rock to new stable substances. Three main reactions contribute to this chemical breakdown. Oxidation: dark silicates react with oxygen, form fe, mg oxides, and clay minerals. Hydrolysis: orthoclase in granite changes to clay by exchanging large k+ ions for tiny h+