EPSC Final Exam Study Guide - Post-Midterm Overview Post-Midterm Lectures Section Section Section Section Section Section Section 7 8 9 10 11 12 13 The

EPSC Final Exam Study Guide - Post-Midterm Overview...

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Post-Midterm Overview 11/26/2014 ° Post-Midterm Lectures: ° ° Section 7 ° Section 8 ° Section 9 ° Section 10 ° Section 11 ° Section 12 ° Section 13
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The Rock Cycle 11/26/2014 ° Sedimentary Rocks ° -Rock that forms at or near the surface of the Earth in one of several ways: by the cementing together of loose clasts (fragments or grains) produced by physical or chemical weathering of preexisting rock; by the growth of sell masses or the cementing together of shells and shell gragments; by the accumulation of subsequent alteration of organic matter from dead plankton or plants; or by the precipitation of minerals from water solution. ° ° Weathering and Sedimentary Rocks ° -The combination of processes that break up and corrode solid rock, eventually transforming it into sediment. ° ° Physical Weathering ° -Breaks intact rock into unconnected grains and chunks. ° 1) Root wedging (as discussed in class): as roots grow, they apply pressure to their surroundings, and can push joints open. ° -This physically causes material to tumble down. ° -Force open cracks, and cause blocks of material to fall down. ° ° 2) Frost wedging: ° -Freezing water busts popes and shatters bottles because water expands when it freezes and pushes the walls of the container apart. ° -The same phenomenon happens in rock. ° -When the water trapped in a joint freezes, it forces the joint open and may cause the joint to grow (force them apart). ° -Ice occupies more space that liquid water. ° ° 3) Sahara dessert (sand) ° -Wind storms picks up sand grains and blasts particles against outcrop and break off tiny pieces of rock. ° -You can physically weather rock (erode flat) with wind (high velocity).
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° ° 4) Glacial action bringing about erosion ° -Go down a river valley, carve river valley, pluck off pieces of rock from the sides of the river valley. ° -It will polish the material underneath (the glacier has rock particles at the base, the rock particles grind over the underlying rock, polishing it, and also plucking out material. ° -If you’re making a scratch, you’re eroding the rock. ° ° *Where would you expect physical weathering? ° -Dry environment, and cold temperatures (a lot of time in the deep freeze) ° ° Chemical Weathering ° -Refers to the many chemical reactions that alter or destroy minerals when rock comes in contact with water solutions and/or air. ° -In the picture: indentations, it appears that the rock has been dissolved (not an effect of mechanical weathering). ° *Where would you expect chemical weathering (environments)? ° -will be maximized when its hot and humid (high rainfall and heat) Why is heat important? Chemical reactions go quicker at high temperature. ° ° ° ° Relative weathering rates of granite and marble ° -Both gravestones were erected at the same time and place
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° -The one on the left is marble, right granite. The marble one has eroded rapidly because its been exposed to acid.
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