Earth History 4.75

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What is an index fossil?

Back

An index fossil is a common fossil found in many areas from a specific time, used to help identify the age of rock layers and for relative dating.

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What is an era in geological time?

Back

An era is a broad span of time based on life existing during that time, which is a subdivision of an eon.

Front

What is the significance of radioactive dating?

Back

Radioactive dating is a method used by scientists to determine the age of the Earth, estimated to be about 4.5 billion years old.

Front

What is an epoch?

Back

An epoch is a subdivision of a geological period.

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What is a trace fossil?

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

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What is the law of superposition?

Back

The law of superposition states that 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 geological period?

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A geological period is a subdivision of an era, characterized by specific types of rock formations and fossil records.

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What are bivalves?

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Bivalves are a class of marine and freshwater mollusks that have a two-part hinged shell, such as clams and oysters.

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What is relative dating?

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Relative dating is a method used to determine the age of rocks and fossils in relation to one another, without providing an exact age.

Front

What is a fossil?

Back

A fossil is the preserved remains or traces of ancient organisms, often found in sedimentary rock.