ANTH 003 Lecture 8: Anth_003_Lecture_8
9 May 2020
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Document Summary
Discovered in 1949 by willard f. libby. The decay of radioactive isotope of carbon could be used to measure time. Importance is that carbon is a fundamental element to all life on earth and is therefore ubiquitous. Subject to gradual decay once an organism dies at a relatively constant rate. Presented in years before present present is 1950 bp subtract point from 1950 the one that libby proposed has been altered a lot since he created it. Helped establish absolute dating radiocarbon dioxide forms in upper atmosphere and is then incorporated into the hydrosphere and the biosphere the amount of radiocarbon in the atmosphere fluctuates, which affects calibration we have created calibration curves. Now we do accelerator mass spectrometry (ams) There are limits it only goes back 30-40,000 years. Bp uncalibrated radiocarbon years before present, with present being 1950 (sometimes rcbp) Bp calibrated years before present (sometimes cal bp) 2500 cal bp +- 190 (2sigma) = 240-360 cal bc (95%)
