ANTH 1220 Chapter Notes - Chapter 3: Willard Libby, Time Capsule, Cyclotron
19 May 2017
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Index fossils = artifacts that indicate periods of time (short time period, unique in shape, widespread geographically) . Willard libby ~ 1949 (first date published 1950) . Measure amount of c-14 (= radioactive isotope, decays at constant rate) . Measure amount of decay to measure amount of time since decay . Nitrogen atoms in atmosphere, cosmic rays hit nitrogen, causing it to release a proton and become c-14 . All living things radioactive, through oxidation c-14 bonds with 2 oxygen atoms carbon dioxide. Half life = time the 1. 2 radioactive material will decay into non-radioactive form (decay rate back to n-14) = 5730 years . Radio carbon dating can date back to 800 000 years with cyclotron . Jesus died in 29 ad, was born in 4 bc = 33 years old (dob was not dec. 5th. C-14 dates with +/- 1000 bp/100 = 1 standard deviation .
