Flashcards SC.7.E.6.3

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What is the law of superposition?

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The principle stating that in undisturbed rock layers, the oldest layers are at the bottom, while newer layers are deposited on top.

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How does the law of superposition help scientists determine the age of Earth’s parts?

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By analyzing the order of rock layers, scientists can estimate the relative age of fossils and geological formations.

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What is radioactive dating?

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A method that uses the decay of radioactive isotopes to determine the absolute age of rocks and fossils.

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What is an isotope?

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Variants of an element with different numbers of neutrons, some of which are unstable and decay over time.

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How does radiometric dating work?

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Scientists measure the ratio of parent isotopes to daughter products to determine how long decay has occurred, revealing a rock’s age.

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What is half-life in radioactive decay?

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The time it takes for half of the radioactive isotopes in a sample to decay into stable elements.

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What is carbon-14 dating used for?

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Dating ancient organic materials, such as fossils or artifacts, up to about 50,000 years old.

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Why can’t carbon-14 dating be used for very old rocks?

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Carbon-14 has a relatively short half-life, making it ineffective for dating rocks millions or billions of years old.

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What methods do scientists use to determine Earth's age?

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Radiometric dating of meteorites and Earth’s oldest rocks, along with analysis of the Moon’s surface.

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How old is Earth estimated to be?

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About 4.6 billion years old, based on radiometric dating of ancient rocks and meteorites.