Carbon dating artefacts
The explanation was that the physicists had assumed that the amount of C-14 in the atmosphere had been constant, when in fact it had varied over time.
The solution came using dendrochronology (tree ring dating).
C is created in the atmosphere by cosmic radiation and is taken up by plants and animals as long as they live.
Upon death, the isotope begins to decay and after 5730±40 years half of it is gone.
As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.Each radiocarbon date has a statistical probability shown by the ± number.This number is called a standard deviation and is a measure of the spread of measurements around the mean (average).But as more dates became available, Egyptologists, who had hieroglyphic records back thousands of years, began to recognize that C-14 dates were generally too young.They proved this by showing that C-14 dates of wooden artifacts with cartouches (dated royal names) did not agree.