When a new technology is discovered, it takes awhile to iron out the bugs. After all, we're still working on improving the heavier-than-air vehicle we call the airplane. One technology that is widely used in our area, as elsewhere, is carbon-14 dating, where material that contains carbon—and this includes all remains of organisms—is dated by the proportion of two different forms, isotopes, of the element carbon. One of these isotopes, carbon 14, is radioactive, disintegrating into nitrogen at a steady rate. These disintegrations are counted, with the number of atoms decaying correlated with the amount of carbon 14 and thus the age.
Despite advances in the ability to count such disintegrations
accurately, a relatively large amount of carbon still is necessary for the technique.
More recently, a method of directly separating the heavier carbon 14 from the more
plentiful, and lighter, carbon 12 has been devised. This allows direct counting of
atoms instead of decay events, and today only minute amounts of carbon are necessary
for dating--such as the carbon contained in only a single seed.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Waikato Radiocarbon Dating Laboratory