Carbon dating live animal
These standard calibration curves assume that at any given time radiocarbon levels are similar and stable everywhere across each hemisphere. "We went looking to test the assumption behind the whole field of radiocarbon dating," Manning said.
Using a mass spectrometer, an instrument that accelerates streams of atoms and uses magnets to sort them out according to mass and electric charge, the group has learned to measure the ratio of uranium to thorium very precisely.Carbon dating is unreliable for objects older than about 30,000 years, but uranium-thorium dating may be possible for objects up to half a million years old, Dr. The method is less suitable, however, for land animals and plants than for marine organisms, because uranium is plentiful in sea water but less so in most soils.But even if the method is limited to marine organisms, it will be extremely useful for deciphering the history of Earth's climate, ice, oceans and rocks, Dr. Dating Subject to Error But scientists have long recognized that carbon dating is subject to error because of a variety of factors, including contamination by outside sources of carbon.
Therefore they have sought ways to calibrate and correct the carbon dating method.Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.