SCIENCE: History of the Earth Review

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What is the Law of Superposition?

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The principle that in any undisturbed sequence of rocks, the oldest layer is at the bottom and the layers above it are progressively younger.

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What is the Theory of Plate Tectonics?

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The theory that the Earth's lithosphere is divided into several large tectonic plates that have been slowly moving for 3.4 billion years.

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What is weathering?

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The process where rocks are broken down by natural forces such as wind or water.

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What is fossilization?

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The process by which an organism's remains are preserved in rock.

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What are Eons in the geologic time scale divided into?

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Eras.

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What is erosion?

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The process by which soil and rock are removed from one location and transported to another by natural forces such as wind or water.

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What is uniformitarianism?

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The principle that the same geological processes that operate today also operated in the past.

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What is relative dating?

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A method of determining the age of a rock or fossil by comparing it to other rocks or fossils.

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What is an unconformity?

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A gap in the geological record that indicates a period of erosion or non-deposition.

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What is the difference between an era and a period in the geologic time scale?

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An era is a larger division of time that encompasses multiple periods.