Radioactive dating fossils dated
This damage is in the form of tiny marks called fission tracks.When volcanic rocks and minerals are formed, they do not contain fission tracks.The number of tracks increases over time at a rate that depends on the uranium content.
Absolute dating is not possible with this method because the rate at which the nitrogen content declines depends on the surrounding temperature, moisture, soil chemicals and bacteria.This newer method converts a stable form of potassium (potassium-39) into argon-39.Measuring the proportions of argon-39 and argon-40 within a sample allows the age of the sample to be determined.This relatively new technique was developed in order to achieve more accurate dates than those obtained from the potassium-argon method.
The older method required two samples for dating and could produce imprecise dates if the argon was not fully extracted.
Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.