Geologic Time

Front

What is the principle of superposition in geology?

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

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What is absolute age in geology?

Back

The 'exact' age of a rock layer or fossil determined by methods such as radiometric dating.

Front

What is relative age in geology?

Back

The age of a rock layer or fossil in comparison to other layers or fossils, without determining its exact age.

Front

What is fossilization?

Back

The process by which organic material is preserved in sedimentary rock, often resulting in the formation of fossils.

Front

What are index fossils?

Back

Fossils of organisms that were widespread but only existed for a short period of time, used to date rock layers.

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What is artificial selection?

Back

The process by which humans breed plants or animals for specific traits.

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What is natural selection?

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The process by which organisms better adapted to their environment tend to survive and produce more offspring.

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What is the significance of the Cambrian Explosion?

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A period in Earth's history (around 541 million years ago) when a rapid diversification of life forms occurred.

Front

What is a geologic time scale?

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A system of chronological dating that relates geological strata to time, used to describe the timing and relationships of events in Earth's history.

Front

What are the main divisions of the geologic time scale?

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Eons, eras, periods, epochs.