Geological Time Scale

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What is the Geological Time Scale?

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A system used by geologists and paleontologists to describe the timing and relationships of events in Earth's history.

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What is an igneous pluton?

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A body of intrusive igneous rock that forms from the cooling and solidification of magma beneath the Earth's surface.

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What is the principle 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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What is a body fossil?

Back

Preserved remains of an organism, such as bones, teeth, or shells.

Front

What is a trace fossil?

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Preserved evidence of the activity of an organism, such as footprints, burrows, or feces.

Front

What is the significance of inclusions in geology?

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Inclusions are fragments of one rock type contained within another; they indicate that the rock containing the inclusion is younger.

Front

What is a cast fossil?

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A fossil that forms when a mold is filled with sediment or mineral deposits, creating a replica of the original organism.

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What is a mold fossil?

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A fossil that forms when an organism leaves an impression in sediment, which later hardens.

Front

What is the Law of Cross-Cutting Relationships?

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Geological features that cut through rocks must be younger than the rocks they cut through.

Front

What is the difference between relative dating and absolute dating?

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Relative dating determines the sequence of events, while absolute dating provides a specific age or date.