MEASUREMENTS OF COSMOGENIC C-14 PRODUCED BY SPALLATION IN HIGH-ALTITUDE ROCKS

The production of radioisotopes at the Earth's surface by cosmic-ray effects has been discussed for many years. Only in the past few years, with the higher sensitivity provided by accelerator mass spectrometry (AMS) in detecting Be-10, Al-26 and Cl-36, have the radioisotopes produced in this way been measured. We report here our measurements of cosmogenic C-14 in terrestrial rocks at high altitude, and comparisons to other exposure-dating methods.