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Calibrating the radiocarbon clock

Carbon-14 decays at a steady, predictable rate, which makes it look like a simple stopwatch for dating ancient wood, bone, or charcoal. However, the amount of radiocarbon in Earth's atmosphere has varied over the millennia, so an accurate date relies on calibrating the measurement against tree rings and other materials whose calendar age is already known.

4–5 min

Questions you could explore

  • How do known-age samples help calibrate a measurement?
  • Why can the result remain a range of possible dates?

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History

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How do archaeologists work out what happened first?

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When Britain’s railways needed a shared clock

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How did reusable type change the making of a page?

History5–7 minIn Gutenberg's Mainz workshop in the 1450s, separate pieces of metal type could form a page and be used again. Printing repeated text, but hand finishing still helped make individual Bibles differ.

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