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 by geologists and other Earth scientists to describe the timing and relationships of events in Earth's history.

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NGSS.MS-ESS1-4

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What are the main divisions of the Geologic Time Scale?

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Eons, Eras, Periods, Epochs.

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NGSS.MS-ESS1-4

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What is an igneous intrusion?

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A body of igneous rock that forms when magma cools and solidifies within the Earth's crust.

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Which layer of rock is typically the youngest?

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The layer that is on top in a sequence of sedimentary rocks, as younger layers are deposited over older ones.

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NGSS.MS-ESS1-4

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What is catastrophism in geology?

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The theory that Earth's features are shaped by sudden, short-lived, and violent events, such as meteor impacts or volcanic eruptions.

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NGSS.MS-ESS3-2

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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, shaping the Earth over long periods.

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NGSS.MS-LS4-1

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What is the significance of fossils in the Geologic Time Scale?

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Fossils provide evidence of past life and help to date the layers of rock in which they are found.

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NGSS.MS-ESS1-4

NGSS.MS-LS4-1

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What does the term 'stratigraphy' refer to?

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The study of rock layers (strata) and layering (stratification), which is crucial for understanding the Geologic Time Scale.

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NGSS.MS-ESS1-4

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How do scientists determine the age of rocks?

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Through methods such as radiometric dating, which measures the decay of radioactive isotopes.

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NGSS.HS-ESS1-5

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What is the Law of Superposition?

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In an undeformed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest are at the top.

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NGSS.MS-ESS1-4