Earth Sciences 2281A/B Lecture 4: Section 4 Notes
24 Jan 2019
School
Department
Course
Professor
Document Summary
Weathering and soil (decay of rock and stone) Examples of things that can weather: water (frost + moisture) Mechanical (physical) weathering: frost action on the large scale. "area where water can get in" bedding planes cleavage planes wedging & heaving pore scale (fine grained rocks susceptible - shale, argillaceous limestone, dolomite, cherty limestone) "as water freezes, it expands, exerting a force great enough to break rock" root wedging. "fractures formed in rock due to plant root expansion" "root wedging expedites already forming fractures thermal stress. "hot/cold/hot/cold cycling" abrasion pressure release - sheet joints and exfoliation. Sheeting = "sheeting is caused by the expansion of crystalline rock as erosion removes the overlying material". When deeply buried pluton is exposed at the triggering mechanisms for rock falls disintegration = smaller frags = > surface area; > chemical weathering. Chemical weathering: minerals adjust to new pressure, temperature, chemistry.
