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8 Cards in this Set
- Front
- Back
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Intrusion |
An Igneous rock layer formed when magma hardens beneath Earth's surface. |
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Extrusion |
An igneous rock layer formed when lava flows on to Earth's ssurface. |
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Uniformitarianism |
Earth is an always changing place. The Same forces at work today were at work in the past. |
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Relative Age |
Age of an event or object in relation to other events or objects. |
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Absolute Age |
Actual Age of an event or object. |
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Index fossil |
Fossils of organisms that were common, that lived in many areas and that existed only during specific spans of time. |
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Superposition
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Layers on the bottom are older than the layers above them. |
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Half-Life |
The length of time that it takes for half of the atoms in a radioactive element to change unstable unto another form. |
