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Taking Abu Simbel apart to save its temples

In the 1960s, the construction of Egypt's Aswan High Dam threatened to submerge the ancient rock-cut temples of Abu Simbel beneath the rising waters of Lake Nasser. Saving them involved an unprecedented engineering rescue: cutting the cliffside monuments into over a thousand numbered stone blocks and rebuilding them on higher ground.

8–10 min

Questions you could explore

  • What information would need to travel with each block?
  • How did reconstruction balance preserving the temples with changing their location?

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History

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

Calibrating the radiocarbon clock

History4–5 minCarbon-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.

History

How do archaeologists work out what happened first?

A deep object is not necessarily the oldest thing at an archaeological site. A later pit can cut through earlier ground, leaving a sequence that has to be reconstructed from relationships between layers.

4–6 min

How do archaeologists work out what happened first?

History4–6 minA deep object is not necessarily the oldest thing at an archaeological site. A later pit can cut through earlier ground, leaving a sequence that has to be reconstructed from relationships between layers.

History

When Britain’s railways needed a shared clock

A timetable becomes awkward when the clocks at its two ends disagree. In nineteenth-century Britain, railway journeys helped turn local time into a shared coordination problem, while the telegraph helped distribute an answer.

5–7 min

When Britain’s railways needed a shared clock

History5–7 minA timetable becomes awkward when the clocks at its two ends disagree. In nineteenth-century Britain, railway journeys helped turn local time into a shared coordination problem, while the telegraph helped distribute an answer.

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