Geological Time Scale

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What is the Great Cambrian Explosion?

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A significant event in Earth's history when most major groups of animals first appeared in the fossil record.

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What is an Eon?

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A unit of geological time equal to a billion years.

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What was The Great Dying?

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A mass extinction event that occurred 252 million years ago, marking the end of the Permian Period.

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What is the Geological Time Scale?

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A chronological chart that shows the events and past lives of organisms in Earth's history.

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What is an Epoch?

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A division of periods in geological history.

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What does the Law of Superposition state?

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

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What is a Period in geological time?

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A subdivision of an era in the geological time scale.

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What is the significance of the Cambrian Period?

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It marks the beginning of the Paleozoic Era and is known for the rapid diversification of life.

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What is a Fossil?

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The preserved remains or traces of ancient organisms.

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What is Uniformitarianism?

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The principle that the same geological processes that operate today also operated in the past.