EARTHSC 1122 Study Guide - Midterm Guide: Ordovician Radiation, Acadian Orogeny, Foreland Basin
12 Apr 2016
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Instead of corals and reefs, we have double coned. More land covered by ocean than any other time during the phanerozoic: life during ordovician, gobe. Ashbed: deformation- crust shortened by 30 miles as the continent hit lorencia, graded bed- from sandstone to shale, depending on grain size, flute casts- form because sandstone forms on top of water-eroded mud ii. Iapetus- close up, form pangea, open again creates atlantic. Can be seen looking at different fossils: can be seen by rock types, fossils, mountain building (orogeny, sea level dropped at the end of the period, because water was not being let back into the oceans. Temperature drop creates glaciers in southern hemisphere: ordovician extinction- caused by cooling of earth and oceans, only adaptive animals survive. Armored, jawed fish called placoderms: end of ordovician period- one of the worst extinctions, 450 ohioan species of fossils a.
