The level of nitrogen gradually reduces as the bone decays.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.Only one sample is required for this method as both the argon-39 and argon-40 can be extracted from the same sample.In special cases, bones can be compared by measuring chemicals within them.
Another useful chemical analysis technique involves calculating the amount of nitrogen within a bone.
Where the rocks are not strongly folded or tilted it is possible to work out the order in which the layers were formed.
The oldest rocks and fossils are at the bottom and the youngest are on top.
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.