Fossil dating accuracy
Fossil dating accuracy
Since 1947, scientists have reckoned the ages of many old objects by measuring the amounts of radioactive carbon they contain.New research shows, however, that some estimates based on carbon may have erred by thousands of years.
- At Oak Ridge National Laboratory, Scientists dated dinosaur bones using the Carbon dating method.
They arrived at this conclusion by comparing age estimates obtained using two different methods - analysis of radioactive carbon in a sample and determination of the ratio of uranium to thorium in the sample.
In some cases, the latter ratio appears to be a much more accurate gauge of age than the customary method of carbon dating, the scientists said.
Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.
Y., reported today in the British journal Nature that some estimates of age based on carbon analyses were wrong by as much as 3,500 years.
The results can be as much as 150 million years different from each other! They then pick the date they like best, based upon their preconceived notion of how old their theory says the fossil should be .
So they start with the assumption that dinosaurs lived millions of years ago, then manipulate the results until they agree with their conclusion. So why is it that if the date doesn't fit the theory, they change the facts?According to carbon dating of fossil animals and plants, the spreading and receding of great ice sheets lagged behind orbital changes by several thousand years, a delay that scientists found hard to explain. The group theorizes that large errors in carbon dating result from fluctuations in the amount of carbon 14 in the air.Changes in the Earth's magnetic field would change the deflection of cosmic-ray particles streaming toward the Earth from the Sun.But the tree ring record goes no further, so scientists have sought other indicators of age against which carbon dates can be compared.One such indicator is the uranium-thorium dating method used by the Lamont-Doherty group.But when a plant or animal dies, it can no longer accumulate fresh carbon 14, and the supply in the organism at the time of death is gradually depleted.