This measures the amount of the radioactive isotope carbon-14 (C) in the sample.There is a certain amount of carbon-14 in all organic matter, and over time it breaks down into carbon-12 or regular non-radioactive carbon. Unfortunately carbon dating is only accurate to 50,000 years with an error of ±500 years. One key problem with isotopic dating (carbon dating) is that it assumes that carbon-14 breaks down to carbon-12 at a constant rate.
The half-life of potassium-40 is 1.3 billion years, far longer than that of carbon-14, allowing much older samples to be dated.
Potassium is common in rocks and minerals, allowing many samples of geochronological or archeological interest to be dated.
After yet another 5,730 years only one-eighth will be left.
By measuring the carbon-14 in organic material, scientists can determine the date of death of the organic matter in an artifact or ecofact.
Carbon-14 moves up the food chain as animals eat plants and as predators eat other animals. It takes 5,730 years for half the carbon-14 to change to nitrogen; this is the half-life of carbon-14.
After another 5,730 years only one-quarter of the original carbon-14 will remain.
These are radioactive elements that have a much longer half-life.
These are used to measure fossils older than 50 000 years of age.
The relatively short half-life of carbon-14, 5,730 years, makes the reliable only up to about 75,000 years.