Relative Dating – Flashcards
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Index Fossil
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a fossil that is widespread geographically but only occurs in one layer or a small number of layers of rock
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Law of original lateral continuity
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sediment deposited into water will spread in a horizontal and continuous sheet
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Law of superposition
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any undisturbed sequence of layered rocks has the oldest rock on the bottom and newest rock on the top
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Paleontology
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study of fossils
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stratigraphy
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study of rock layers and the processes that form them
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Law of original horizontality
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sediment deposited into water will settle at the bottom in flat, horizontal layers
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Law of faunal and floral succession
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animals and plant fossils occur in consistent sequences through time, generally changing from simpler to more complex
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Law of cross-cutting (or intrusive) relationships
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in a sequence of layered rocks, the crosscut, or intrusive feature, is younger than the layers it intercedes
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Relative dating
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process to determine the general time sequence of historic events, rock strata, and fossils
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In ___________ you study rock stata, and in __________ you study fossils.
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Stratigraphy and Paleontology
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The Law of Superposition states:
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rock layers closest to the surface are the newest or youngest rock.
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When sediments deposit in lakes or oceans, how do they lay?
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in flat horizontal layers
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The law of original horizontality explains:
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why rock layers are always flat
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Sediment layers stop lateral spreading when:
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they encounter a barrier and they run out of additional sedimentary material
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Match each law or principle to its description. 1. law of original horizontality 2. law of superposition 3. law of original lateral continuity 4. law of cross-cutting or intrusive relationships
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__________________________________________________________________________________________________________________________________________________________________
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A geologist is studying layers of rock. He finds a fossil with an imprint of a shelled animal. According to the law of faunal and floral succession, what kind of fossil would he most likely find next, in the layer of rock above it? Look back to the Fossil Succession Chart for help.
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a fossil of fishes
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A fossil that is widespread geographically but only occurs in one or a small number of rock layers is called _____.
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an index fossil
