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10 Cards in this Set
- Front
- Back
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Precambrian Time |
-plants(blue-green algae): more photosynthesis=more oxygen -"Cambrian explosion": oceanic organisms appear at start of paleozoic era |
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Paleozoic Era |
"Age of Invertebrates" -ocean dwelling organisms -atmospheric comp changed with evolving life forms -life forms with shells, scales, bones |
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Mesozoic Era |
"Age of Reptiles" -dinosaurs -cretaceous extinction (end of era) -caused by large impact of meteor |
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Cenozoic Era |
"Age of Mammals" -present era -mountain ranges -dramatic changes in climate |
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Permian extinction |
-end of Paleozoic -96% of marine species & 8 out of 27 orders of insects -caused by enormous volcanic eruptions |
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index fossils |
fossils that occur only in rock layers of particular time period |
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cross-cutting relationship |
fault or igneous intrusion is younger than the rock it cuts through above and below the unconformity |
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original horizontality |
sedimentary rocks left undisturbed will remain in horizontal layer |
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laws of superposition |
undeformed sedimentary rock layer is older than layers above it and younger than layers below it |
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uniformitarianism |
current geological processes are the same processes that were at work in the past |
