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Review_for_Midterm_2 - Revi ew for Midterm II The mos t...

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Review for Midterm II The most important concepts from each chapter that we have covered are summarized below. In addition, you should spend some time going over the review questions at the end of each chapter – a good way to do this is to work together on this with some of your classmates. The exam will be 50 minutes long, and a mix of multiple choice, word match, and fill in the blanks. Good luck with your studying! Chapter 6 Sedimentary Rocks 1. You should know that sediments and sedimentary rocks are the most abundant solid Earth materials at the surface, even though they are rare in the crust as a whole. 2. You should be familiar with the sedimentary rock cycle, understanding physical and chemical weathering , erosion , transport , deposition , and lithification . 3. You should be able to distinguish among coarse-, medium- (sand), and fine-sized grains and know what is meant by sorting , sphericity , and angularity among sediments and rocks. 4. Clastic sedimentary rocks are primarily classified on the basis of grain size. You should be able to recognize and characterize conglomerate , breccia , sandstone , siltstone , mudstone , and shale . 5. Biologically catalyzed precipitation produces mineralized skeletons; these condense and lithify to form biochemical sedimentary rocks . Important examples are most limestones and bedded, biogenic cherts . 6. Organic sedimentary rocks (the coal series) consist of the altered remains of trees and other plants that lived in boggy environments (which allow organic matter to accumulate without too much decay). 7. Chemical sedimentary rocks arise from physically induced precipitation. As with biochemical rocks, classification is primarily on the basis of mineral content. An important subset are the evaporites , including rock salt (halite) and gypsum (small amounts of carbonate sediment can also form through evaporation). Chemical rocks can also form through the replacement of minerals during diagenesis; important replacement minerals include quartz (forming the rock called chert) and dolomite (forming dolostone). 8. The layering of rock is termed stratification (or bedding ); cross beds signify deposition along a slope and can be used to indicate paleocurrent direction. Other features of interest within sedimentary rocks include fossils , ripple marks , and mud cracks . 9. The character of sedimentary rocks reflects their environments of deposition ; You should be familiar with a few sedimentary environments (e.g., alluvial fan, fluvial, shallow marine, deep marine, glacial ) and characteristics of the sediments deposited in these realms. Locally, environments change over time; one source of these changes is the sequence of transgressions (rising local relative sea level) and regressions (falling local relative sea level).
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Answers to some of the review questions- Sedimentary rocks 1. Describe how a clastic sedimentary rock forms from its unweathered parent rock .
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Review_for_Midterm_2 - Revi ew for Midterm II The mos t...

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