Dating of sedimentary rocks

23 Apr

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.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.

It is possible to calculate the age of a sample by measuring the uranium content and the density of the fission tracks.The age of volcanic rocks and ash can be determined by measuring the proportions of argon (in the form of argon-40) and radioactive potassium within them.Each volcanic eruption produces a new deposit of ash and rock.Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.Uranium is present in many different rocks and minerals, usually in the form of uranium-238.