Use of radioactive isotopes in carbon dating
Plants take in atmospheric carbon dioxide by photosynthesis, and are ingested by animals.
The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 50,000 ft).For carbon, there are a lot of C-12, a couple of C-13, and a few C-14 atoms.When you average out all of the masses, you get a number that is a little bit higher than 12 (the weight of a C-12 atom). Geologists use those radioactive isotopes to date volcanic ash or granite formations like the giant Half Dome in Yosemite National Park. Yes, radioactive isotopes present in rocks and other ancient material decay atom by atom at a steady rate, much as clocks tick time away.
One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.