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22 Cards in this Set
- Front
- Back
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Eras in order from oldest to youngest
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Precambrian, Paleozoic, Mesozoic, Cenozoic
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Periods in Precambrian era oldest to youngest
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Cambrian, Ordovician, Silurian, Devonian, Parboniferous, Permian
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Periods in Mesozoic era oldest to youngest
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Triassic, Jurassic, Cretaceous
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Periods in Cenozoic era oldest to youngest
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Tertiary, Quarternary
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Absolute dating
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provides more precise measurement of geologic time
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Relative dating
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logical sequence
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Law of Superposition
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youngest layer is on top and oldest is at the bottom
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Crosscutting relationships
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cuts through pre-existing rock formations
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Uniformitarianism
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laws of nature that dont change with time
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3 times of unconformities
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angular unconformity, nonconformity, and disconformity
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Angulary unconformity
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horizontal strata deposited on top of tilted rock layers
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Nonconformity
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stratified rock is deposited on top of nonstratified rock.
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Disconformity
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stratified rock is deposited on top of other horizontal strata separated by erosion.
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How do the unconformites pose problems in determining dating?
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They all show disruption to the horizontality
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Intrusion
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a mass of igneous rock formed from magma that intruded another rock body.
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Inclusion
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pieces of one rock unit that are contained within the other, older rock fragments.
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Fossil
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remains or traces of an organism preserved from the geologic past. Proof of geologic time.
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Petrification
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minerals replace organic material molecule by molecule.
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Mummification
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drying often found in desert areas because bacteria can't surbibe without water - organism doesn't decay.
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Amber fossil
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hardened tree sap. Insects and other creatures get caught in it and are preserved.
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Gastrolith
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stones in the digestive system that help to grind food.
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Coprolite
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fossilized dung or waste material, reveals eating
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