3 ms·
Carbon 14 has a half-life of 5,730 years. After 57,300 years, only 1/1024 of the original carbon 14 will remain. After 300,000 years, about 1.73 * 10^-16 of t
by yongjik 9y ago
Carbon 14 has a half-life of 5,730 years. After 57,300 years, only 1/1024 of the original carbon 14 will remain.
After 300,000 years, about 1.73 * 10^-16 of the original carbon will remain, which is obviously too little.
- jessriedel 9y ago> which is obviously too little To fill in the detail: Carbon-14 has an abundance of about 1 part in 10^12, and one gram of carbon contain about 10^23 carbon atoms, so about 10^11 C-14 atoms. Every single C-14 atom will have decayed in about 200k years.
- rurban 9y agoCarbon-14 decay is only usable up to max 70.000 years. But there exist many other long-lived isotopes to measure. The uranium-thorium method, the potassium-argon method, and the rubidium-strontium method. Samples containing radioactive beryllium could be dated as far back as 10–30 million years. A newer method of radioactive tracing involves the use of a new clock, based on the radioactive decay of 235 uranium to 231 protactinium. We'd really like to know why the known accurate methods didn't work in this case, and why they had to fall back to indirect measurements of the flint stones.