Potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive argon to radioactive potassium in the rock. This dating method is based upon the decay of radioactive potassium-40 to radioactive argon-40 in minerals and rocks; potassium-40 also decays to calcium-40.

What has been found with radiometric dating?

Used primarily for remains found in archeological contexts, radiocarbon analysis can provide absolute dating for remains likely of considerable antiquity. This approach recognizes that the isotope carbon-14 is mildly radioactive and decays at a predictable rate. The half-life of carbon-14 is about 5730 years.

What is uranium lead dating used for?

Uranium–Lead dating is the geological age-determination method that uses the radioactive decay of uranium (U) isotopes (238U, 235U, and also in this entry 232Th) into stable isotopes of lead (Pb) (206Pb, 207Pb, and 208Pb, respectively).