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15 Cards in this Set
- Front
- Back
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Geology |
Study of the origin, history and structure of Earth and the processes that shape it. |
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Catastrophism |
Principal that states that all geologic change occurs suddenly. |
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Catastrophe |
Unpredictable events caused rapid change over large areas, sometimes globally. Ex: volcanic erruption |
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Uniformitarianism |
The same geologic processes that shape Earth today have been at work throughout Earth's history. Geologic change is slow and relatively constant over time. |
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Geologic Time Scale |
Divides Earth's history into intervals of time defined by major events or changes on Earth. |
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The geologic time scale divides Earth's geologic history into these 4 geologic times: |
Eons, eras, periods and epoch |
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Eon |
Largest unit of geologic time |
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Earth's 4.6 billion year history is divided into these 4 eons: |
Hadean, Archean, Proterozoic and Phanerozoic Eons |
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Divisions of geologic time scale: |
The geologic time scale has no fixed lengths. Many divisions are based on events in Earth's geologic history: Fossil records, large mass extinction events |
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Mass extinction events |
Larger than expected number of organisms disappear from the fossil record in rock layers worldwide. |
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Causes of mass extinction: |
Movements of the continents, lowering of global sea level, rapid climate change and asteroid impacts |
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Precambrian Time |
Began with formation of Earth 4.6 billion years ago Earth formed into spherical planet and molton rock cooled Continents began to form Land on Earth was largely frozen and lifeless |
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Paleozoic Era |
540 million years ago Global supercontinent of Pannotia was breaking up All life was found in the ocean at the start of the era Life diversified quickly & dramatically during Cambrian Explosion - major groups of organism evolved Era ended with huge mass extinction event
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Mesozoic Era |
Began 250 million years ago Pangaea began to break up Shallow seas covered the land Earth's crust began to fold forming mountains Climate - warm Life during this era was domintated by dinosaurs Mass extinction 65 million years ago ended this era - caused by asteroid impact |
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Cenozoic Era |
Began 65 million years ago with Cretaceous mass extinction and continues to present. Continents assumed their present positions Climat turned cooler on land & oceans & polar ice caps formed Temperature differences between the poles and equator became extreme Divided into 2 periods: Teriary and Quaternary |
