GMO chapter 9
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Created by:
14JGrindinger on November 15, 2011
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10 terms
Terms | Definitions |
|---|---|
 geologic column | an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom |
| era | a unit of geologic time that includes two or more periods |
| period | a unit of geologic time that is longer than an epoch but shorter than and era |
| epoch | a subdivision of geologic time that is longer than an age but shorter than a period |
| evolution | the process of change by which new species develop from preexisting species over time |
| Precambrian time | the interval of time in the geologic time scale from Earth's formation to the beginning of the Paleozoic era, from 4.6 billion to 542 million years ago |
| Paleozoic Era | the geologic era that followed Precambrian time and that lasted from 542 million to 251 million years ago |
| mass extinction | an episode during which large numbers of species become extinct |
| Mesozoic Era | the geologic era that lasted from 251 million to 65.5 million years ago; also called the "Age of Reptiles" |
| Cenozoic Era | the current geologic era, which began 65.5 million years ago; also called the "Age of Mammals" |
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