Earth’s History

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What is the law of crosscutting relationships?

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The law of crosscutting relationships states that a geological feature (like a fault or igneous intrusion) that cuts through another feature is younger than the feature it cuts.

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What is an ice core?

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An ice core is a cylindrical sample of ice drilled from an ice sheet or glacier, which contains layers that provide information about past climate conditions.

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What is radiometric dating?

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Radiometric dating is a method used to determine the age of rocks and fossils by measuring the decay of radioactive isotopes.

Front

What does the fossil record indicate about the evolution of species?

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The fossil record shows that many animals in the fossil record are ancestors of modern animals, indicating evolutionary changes over time.

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How old is Earth according to current radiometric dating?

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Earth is approximately 4.6 billion years old.

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What is the principle of superposition?

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The principle of superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

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What is coprolite?

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Coprolite is fossilized dung that provides information about the diet and behavior of ancient organisms.

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What are tree rings used for in studying Earth's history?

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Tree rings can be used to determine the age of a tree and provide clues about past climate conditions, such as rainfall and temperature.

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What is the significance of potassium-40 in dating rocks?

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Potassium-40 is a radioactive isotope used in radiometric dating to determine the age of igneous rocks by measuring its decay to argon-40.

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What is relative dating?

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Relative dating is a method of determining the age of rocks and fossils by comparing their placement in layers of rock.