1700 Using Fossils 2011 - EAS 1700 Page 1 of 5 USING...

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E AS 1700 Page 1 of 5 21 April 2011 U SING F OSSILS I NTRODUCTION Previous classes have introduced many but by no means all of the applications of fossil evidence in studying the history of the earth and life: characterizing ancient environments (e.g. Classes 1, 4, 17, Exercise 6); age-dating rocks (e.g. Class 5, Exercise 2), charting paleogeography (e.g. Class 7, Exercise 4); studying geochemical cycles (e.g. Classes 8, 13, Exercise 6); studying the formation of sedimentary rock (e.g. Exercise 9), tracing the evolution of life (Classes 19–), and understanding the preservation of fossil fuels (e.g. Classes 8, 18). The present exercises demonstrate certain types of fossils and their uses and importance in these applications and more. I DENTIFYING F OSSILS TO D ATE R OCKS B RACHS , CLAMS , AND COQUINA Today, and throughout much of the Mesozoic and Cenozoic, clams are so prevalent in shallow- water marine sediments that their shells make up most of the rock. Coquina 1 , a porous limestone comprised of loosely cemented shell fragments, can form in as little as a year on shell beaches. Coquinite is a general term for limestone comprised largely of shells of whatever nature. Coquinites comprised largely of brachiopod shells were deposited in shallow seas that covered continental interiors at times of highest sea level between the Ordovician and the Permian. The Amorphognathus superbus (A.s.) limestones in the “Building a Time Scale …” exercise are comprised largely of the shells of the brachiopod Paucicrura rogata , as are similar limestones that blanket North America from New York to Colorado. Ever since the mass extinction at the the end of the Permian, however, brachiopods have been a minor phylum comprised of lamp shells and their allies. E XERCISE 1: Examine the specimens in the containers labelled “mixed clams” and “mixed brachiopods” until you feel confident you can distinguish clams from brachiopods based on the symmetry of the shell. Then pick out and identify by letter and/or number two pieces of Paleozoic rock. I A
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This note was uploaded on 09/24/2011 for the course EAS 1560 taught by Professor Monger during the Spring '09 term at Cornell University (Engineering School).

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1700 Using Fossils 2011 - EAS 1700 Page 1 of 5 USING...

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