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2
|
Magma cools and hardens into a mass of igneous rock.
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4
|
Solid mineral material.
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5
|
Tells scientists the number of years ago a rock layer formed.
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6
|
the time taken for the radioactivity of a specified isotope to fall to half its original value.
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8
|
A rock is its age compared to the ages of other rocks.
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10
|
Lava that hardens on the surface.
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1
|
A gap in the geologic record.
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3
|
Sometimes, forces inside earth rock layers so much that the layers are turned over completely.
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7
|
Thickness of material.
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9
|
A prehistoric organism preserved.
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