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21 Cards in this Set
- Front
- Back
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Absolute age |
The actual age of a rock or an event in years |
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Principle of Superposition |
The idea that each overlaying layer is then progressivly younger, so that the top layer is the youngest, or most recently formed |
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Intrusion |
When magma squeezes into preexisting rocks and crystalizes |
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Extrusion |
When lava flows on Earths surface and solidifies |
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Inclusion |
A body of older rock within igneous rock |
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Cross cutting relationships |
Intrusions, faults, joints, and viens are all examples of cross cutting relationships |
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Correlation |
This process makes it possible to show that rocksor geologic eventsfrom different places are the same or similar in age |
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Bedrock |
Is usually covered by soil, other loose materials, or human-built structures |
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Fossils |
The remains or evidence of former living things |
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Index fossils |
The fossils used in correlations |
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Vocanic ash |
Sand sized to clay sized particles of extrusive igneous rock that is shot into the air furing volcanic erruptions |
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Geologic time scale |
A model of the divisions of geological time |
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Unconformities |
Evidence of burried eroded surfaces |
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Isotopes |
The several varieties that most to many elements exist in |
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Radioactive decay |
When the nuclei of many atoms within isotopesemit particles and electromagnetic energy |
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Urainium-238 |
One of the most important isotopes in dating rocks is Uranium-238 |
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Half life |
The time required for half of the atoms in a given mass of an isotope to decay |
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Radioactive Dating |
A method in which the half-life of a radioactive isotope can be used along with the ratio between the amount of the original isotope and the amount of its Decay product to estimate the absolute age of a rock sample |
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Carbon-14-Dating |
Also called radiocarbon dating can be used to date rocks and organic remains such as bones of a Mastodont up to approximately 70000 years in age |
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Organic evolution |
The theory of organic evolution states that life forms change Through Time as environmental conditions change variations within a species could certain individuals a greater chance of surviving and reproducing |
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Out gassing |
Gases from the Earth's interior seats help of the crust through cracks and volcanic eruptions in a process called outgassing |
