Time change of radioactive dating
So we knew about "deep time," but exploring it was frustrating.
For more than a hundred years the best method of arranging its history was the use of fossils or biostratigraphy.
Carbon 14 is thought to be mainly a product of bombardment of the atmosphere by cosmic rays, so cosmic ray intensity would affect the amount of carbon 14 in the environment at any given time.
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.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.The Lamont-Doherty scientists conducted their analyses on samples of coral drilled from a reef off the island of Barbados.The samples represented animals that lived at various times during the last 30,000 years. Alan Zindler, a professor of geology at Columbia University who is a member of the Lamont-Doherty research group, said age estimates using the carbon dating and uranium-thorium dating differed only slightly for the period from 9,000 years ago to the present.