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22 Cards in this Set
- Front
- Back
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Fossils
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Remains, imprints, traces of animals or plants that died long ago.
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Permineralized remains
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fossils in which spaces are filled with mineral from groundwater
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mold
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a body fossil that forms when an organism decays, or dissolves and leaves a cavity in the rick
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cast
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a body fossil that forms when minerals fill a mold and harden into rock
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Index Fossil
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remains of species that lived for a short time, were numerous, and were found in many places.
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carbon film
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thin film of carbon left from an organism and preserved as a fossil
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Relative Age
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the age of something compared to the age of other things
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Unconformity
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Gaps in rock layers
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Angular Conformities
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New layers forming on tilted layers
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Disconformity
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When a rock layer is missing
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nonconformities
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Occurs when metamorphic or igneous rock are uplifted or eroded
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Principle of Superposition
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states that in undisturbed rock layers, the oldest rock is at the bottom and the rocks become younger and younger towards the top
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Absolute Age
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the age , in years, of a rock or other object
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Radioactive decay
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the process in which the nucleus of an atom breaks down
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Alpha decay
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An isotope gives off two protons and two neutrons in the form of an alpha particle
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Beta Decay
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The nucleus loses one neutron but gains one proton
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Half life
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The time it takes for an isotope to decay
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Uniformitarianism
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principle that earth's processes occurring today are similar to those that occurred in the past
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Relative dating
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Order of events of dates of rocks are determined by examining the positions of rocks in layers
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Radiometric dating
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geologists can calculate absolute age of a rock by knowing the half life of an isotope
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Carbon dating is used to date.....
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Organic matter ONLY
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Half life of uranium 238 is...
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4.47 billion years and is used to date rocks
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