Carbon dating is a technique used to determine the age of organic material by measuring the radioactivity of its carbon content. It is a relative dating method, which means that it can only provide an estimate of the age of a sample. Carbon dating is most effective on samples that contain organic material, such as wood, charcoal, bone, or shell.
The radioisotope 14C (carbon-14) is produced in the upper atmosphere by cosmic rays. Plants and animals absorb 14C during their lifetime and when they die, they stop taking in new 14C. The amount of 14C in a sample decreases over time as it decays into nitrogen-14. By measuring the amount of radioactivity remaining in a sample, we can calculate how long ago the plant or animal died.
Carbon dating has been used to date objects as old as 50,000 years ago. It is accurate to within ±40 years for samples younger than 1,000 years old and ±60 years for samples older than 1,000 years old. The main limitation of carbon dating is that it can only be used to date materials that contain carbon—it cannot be used to date minerals or other inorganic materials.