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23 Cards in this Set
- Front
- Back
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Fossils
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The remains or evidence of a living thing.
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Radioactive Dating
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Using the half-life of radioactive isotopes (such as Carbon-14) to determine the age of an object.
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Absolute Dating
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Determining the exact time of an event, or the exact age of an object.
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Petrification
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(Means turning into stone) - as water seeps through the earth it dissolves minerals in the mud and sand. As the water evaporates, the minerals are left behind.
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Mold
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The soft and hard parts of the organisms disappear leaving an empty space with the same shape as the organism.
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Cast
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A mold is filled in by minerals in the sediment.
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Imprints
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An object leaves an impression in soft sediments such as mud. When the sediments harden into rock, the imprint is preserved as a fossil.
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Trace fossils
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Marks or evidence of animal activities that have become fossilized. (Ex. tracks, trails, footprints, burrows).
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Coprolites
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Fossilized excrement of animals
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Preservation of an Entire Organism
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Decay was stopped completely (or slowed to almost zero), thus preserving the organism’s body.
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Tar pits - Preservation of an Entire Organism
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Animals became trapped in large pools of tar (possibly when trying to drink the water covering the tar pit, or to eat the already trapped animals). The trapped animals eventually sank to the bottom of the pit.
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Amber - Preservation of an Entire Organism
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Insects become trapped and preserved in hardened tree sap (resin).
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Freezing - Preservation of an Entire Organism
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Ex: Wooly mammoth fossil
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Uniformitarianism
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A theory developed by Hutton and Lyell commonly explained as “the present is the key to the past”.
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Relative Dating
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Determining the order of events, even if the exact time is uncertain.
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Stratigraphic Principles
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Examination of strata (layers) to determine age (called stratigraphic time).
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Law of Superposition
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In a series of sedimentary rock layers, the oldest layer is on the bottom.
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Biostratography
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The assumption of early geologists that sediments containing similar fossils were of similar ages, regardless of where on the surface of the earth the sediments were found.
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Index Fossils
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Fossils of organisms that lived during only one period of time.
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Facies Fossils
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Fossils that only live in a certain environment.
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Fault
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A break or crack along which rocks move.
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Intrusion
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Magma that has forced its way into layers of rock from below and hardened (become igneous rock).
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Extrusion
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Igneous rock that formed on the Earth’s surface.
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