Geologic Time Scale & Earth's History

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Geologic Time Scale

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Organizes Earth's history into eons, eras, periods.

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Rock Strata

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Layers of sedimentary rock, used to date Earth's history.

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Fossils

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Remains of ancient life, found in rock layers.

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Eons

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Largest time units in geologic time scale.

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Eras

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Subdivisions of eons, marked by major events.

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Periods

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Subdivisions of eras, defined by life forms.

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Epochs

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Subdivisions of periods, finer time scale.

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Relative Dating

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Determines age of rock layers compared to others.

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Absolute Dating

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Determines exact age using radioactive decay.

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Paleontology

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Study of fossils to understand past life.