Dating rocks with uranium 238
This technique is primarily used to date igneous rocks.Radioactive dating is only useful in dating igneous and metamorphic rock.Radiometric dating uses the half-life of naturally occurring radioactive isotopes and their products to date rocks.
Rocks found in the earth are usually older than the rocks found above them.
The four isotopes are uranium-235, uranium-238, lead-207, and lead-206.
The process of dating finds the two ratios between uranium-235 and lead-207; and uranium-238 and lead-206.
Relative dating is used to determine the relative ages of geologic strata, artifacts, historical events, etc. Both U-238, and C-14 (radiocarbon, for carbon dating) are used to estimate the age of certain types of matter.
These atoms decay, and from the amount of atoms remaining, an estimate of the age can be made.
Some rock formations show layers of sediment that can be uniquely dated.