Geologic Time Scale

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What is the Geologic Time Scale?

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A system of chronological dating that relates geological strata to time, used to describe the timing and relationships of events in Earth's history.

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What is Absolute Age?

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The exact age of a rock or fossil, often expressed in years.

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What is Relative Age?

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The age of a rock layer compared to the ages of other rock layers.

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What is an Index Fossil?

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A fossil that is used to define and identify a particular time period in the geologic time scale.

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What does the Principle of Superposition state?

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In undisturbed rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

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What is a Trace Fossil?

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A fossil that provides evidence of the activity of ancient organisms, such as footprints or burrows.

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What is a Mold Fossil?

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A fossil formed when an organism is buried in sediment and then decays, leaving an impression.

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What is a Cast Fossil?

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A fossil that forms when a mold is filled with minerals or other materials, creating a replica of the original organism.

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What is the significance of the Coconino Sandstone?

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It is a geological formation that is approximately 280 million years old, providing insights into ancient environments.

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What is the difference between Absolute Age and Relative Age?

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Absolute age is the exact age in years, while relative age is the comparison of ages between different rock layers.