Why radioactive dating is wrong
This illustrates the whole problem with the radioactive dating of geological events.
Many events can affect the levels of carbon-14 in the atmosphere, such as the burning of fossil fuel or the detonation of an atom bomb.
A swimming race illustrates the simple principles involved in measuring time.
This swimmer is competing in a 1,500 metre race and we have an accurate, calibrated wristwatch.
Radiocarbon dating, which is used to calculate the age of certain organic materials, has been found to be unreliable, and sometimes wildly so - a discovery that could upset previous studies on climate change, scientists from China and Germany said in a new paper.
Their recent analysis of sediment from the largest freshwater lake in northeast China showed that its carbon clock stopped ticking as early as 30,000 years ago, or nearly half as long as was hitherto thought.