Take the FREE & fun all about Layers of Rocks quiz and download FREE all about Layers of Rocks worksheet for kids. Climate records from a Japanese lake are set to improve the accuracy of the dating technique, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct.But that assumes that the amount of carbon-14 in the atmosphere was constant — any variation would speed up or slow down the clock.The clock was initially calibrated by dating objects of known age such as Egyptian mummies and bread from Pompeii; work that won Willard Libby the 1960 Nobel Prize in Chemistry.
But this sediment doesn't typically include the necessary isotopes in measurable amounts.
Since the 1960s, scientists have started accounting for the variations by calibrating the clock against the known ages of tree rings.
As a rule, carbon dates are younger than calendar dates: a bone carbon-dated to 10,000 years is around 11,000 years old, and 20,000 carbon years roughly equates to 24,000 calendar years.
Sedimentary rock forms in layers over millions of years.
If you look at a cliff made from sedimentary rock, you’ll notice distinct layers that may even be different colors.
The recalibrated clock won’t force archaeologists to abandon old measurements wholesale, says Bronk Ramsey, but it could help to narrow the window of key events in human history.