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Time, fossils, tectonic plates

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Across
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Tectonic plates are pieces of this layer
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Sea floor spreading is when plates drift ______
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The amount of time it takes for half of a radioactive sample to decay into a stable form
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Tectonic plates float on this layer.
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The first eon of the earth when there was no life of any kind
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The era when plants and animals first appeared on land
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A method of determining the age of an object by comparing the amount of a radioactive parent isotope to the stable daughter isotope
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Wegener thought that the continents had once been joined together because he found matching _______ on the coasts of certain continents.
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The longest periods of geologic time
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An atom that has the same number of protons as other atoms of its kind, but a different number of neutrons, possibly making it unstable
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The era that's called the age of the reptiles
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The entire geological column is found in this layer of the earth.
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Earthquakes produce these waves
Down
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Who first proposed the idea of Pangaia?
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A scientist who studies fossils
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The molten rock that comes up from the mantle
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A scientist who studies rocks
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The dense center of the earth
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Relative dating is when paleontologists ________ the age of one thing with the age of something else.
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The name of the supercontinent that existed 245 million years ago
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The fossil of an organism which is known to have lived during a particular time in geologic history. These fossils are useful in determining the age of a rock sample.
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The era in which we live
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A piece of an era
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A convergent boundary is where plates come ________