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 to describe the timing and relationships of events in Earth's history.

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What does 'relative age' mean in geology?

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The age of one rock layer or fossil compared to another, indicating whether it is older or younger.

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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 pre-existing rock layers.

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What is a 'carbon film' fossil?

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A type of fossil preservation where only a thin layer of carbon remains, often showing details of the organism.

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What is a 'fault' in geological terms?

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A fracture or zone of fractures between two blocks of rock, allowing for movement.

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What is an 'inclusion' in geology?

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A piece of one rock unit that is contained within another, indicating that the included rock is older.

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What does 'unconformity' refer to in geology?

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A surface of contact between two groups of unconformable strata, representing a gap in the geological record.

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What is the significance of the Law of Superposition?

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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 radiometric dating?

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A method used to determine the age of rocks and fossils based on the decay of radioactive isotopes.

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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 that hardens.