Unit Review: Geologic Time, Fossils, Geologic Dating

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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, divided into eons, eras, periods, epochs, and ages.

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What is a fossil?

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The preserved remains or traces of ancient organisms, often found in sedimentary rock.

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What is an intrusion in geology?

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A body of igneous rock that has formed from magma that has cooled and solidified within the crust of the Earth.

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What is a mold fossil?

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A fossil that forms when an organism decays and leaves an impression in the rock.

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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 sediment, creating a replica of the original organism.

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What are petrified fossils?

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Fossils that form when organic material is replaced by minerals, turning the remains into stone.

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What is a trace fossil?

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Fossils that provide evidence of the activities of ancient organisms, such as footprints or burrows.

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What is amber?

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Fossilized tree resin that can preserve small organisms, such as insects, within it.

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What is coprolite?

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Fossilized dung that provides information about the diet of ancient organisms.

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What is the significance of mass extinctions in the geologic time scale?

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Mass extinctions mark significant changes in biodiversity and are used to define boundaries between different geological periods.