GEOL 256 Lecture Notes - Lecture 20: Plate Tectonics, Source Rock, Subduction
13 Nov 2020
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Document Summary
Rocks formed from sediment that was transported by water, ice, or wind. 75% of earth"s surface, only 5% of crust. Sedimentary rocks are made a the interface between the crust and the atmosphere. Sediments generated at the surface because of weathering and erosion. Minerals are stable at different temperatures and pressures - determines location of rocks. High topography = easy weathering = topographic gradient = further movement. Processes break up pre-existing rock by mechanical, chemical, or biological means. Frost wedging, glacial scour, physical and chemical weathering, freeze-thaw cycles. Removal of sediment away from the source. Processing = rounding, sorting by size and minerals. Longer time and distance of transportation, more rounding and sorting. Maturity = level of processing, not age. Quartz is most resistant to chemical weathering. Law of superposition: layer on bottom is oldest and layer on top is youngest. Physical and chemical process by which sediments are lithified into sedimentary rocks.
