ANTH 102 Lecture Notes - Lecture 34: Carbon-14, Pumice
Introduction to Human
Origins
Chronometric Dating
(Radiocarbonate and
Potassium Argon)
Spring 2018
A.
Radiocarbon analysis- when an organism die, the carbon 14 fraction in organic
material declines at a fixed rate. The amount remaining in a sample can be used
to estimate age.
- Living things have carbon 12/14 inside. (ex: charcoal.) When organism dies,
decomposition beings.
- All you have to know is how long this process takes
- This is called a half-life.
- Difference between carbon 12 and 14
- Carbon 14- half-life of 5730 years
- Takes 5730 years for half of carbon 14 to radioactively decay
- Accurate to about 50,000 BP
find more resources at oneclass.com
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Document Summary
Radiocarbon analysis- when an organism die, the carbon 14 fraction in organic material declines at a fixed rate. The amount remaining in a sample can be used to estimate age. Living things have carbon 12/14 inside. (ex: charcoal. ) All you have to know is how long this process takes. Takes 5730 years for half of carbon 14 to radioactively decay. Gets inaccurate after that because there is hardly in carbon in sample after. Works very well in americas because there are no sites older than 15,0000 years old. Measures radioactive potassium 40 that has decayed into argon gas in volcanic material. Volcanic pumice, crystal etc. has potassium 40 in it. Release gas, measure, and know half life. This used to date oldest fossils and volcanic material on earth. Site has to be very old (at least 100,000 or 200,000 years old to have measurable amounts of argon. )
