How do geologists use radiometric dating to estimate the age of rocks?
Quick Answer
They measure the ratios of parent isotopes to daughter isotopes and compare them with known decay rates. Different methods work for different materials and timescales.
The Full Story
Radiometric dating works because unstable isotopes decay at predictable rates called half-lives. A mineral can trap parent isotopes when it forms, and over time those atoms turn into daughter products. By measuring the ratio between them, scientists calculate how long the decay has been occurring. Common methods include uranium-lead dating for very old rocks, potassium-argon dating for volcanic material, and carbon-14 dating for once-living things up to about 50,000 years old. The technique is one of the main tools used to date Earth's history and the geologic time scale.
Key Facts
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"Rocks can tell time—here’s how scientists read their age in atoms."
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