ENV 151 Study Guide - Quiz Guide: Unconformity, Black Carbon, Gastrolith
13 Dec 2018
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The philosophy of catastrophism viewed the earth as being about 5000 or so years old, while uniformitarianism recognizes the earth as being much older: distinguish between numerical dates and relative dates. Numerical dates give us known ages of rocks and rock layers. These breaks in the rock record represent times of significant geologic events. They can help us identify intervals of time not represented in the rock record: distinguish among angular unconformity, disconformity, and nonconformity. An angular unconformity is an area in which rocks have been tilted and uplifted, then had horizontal deposition begin anew atop these tilted layers. A disconformity is a region where erosion rather than deposition occurred, as between two sedimentary layers widely separated in age. A nonconformity is a boundary between igneous or metamorphic rocks and sedimentary strata: describe several ways that an animal or a plant can be preserved as a fossil.
