These rates of decay are known, so if you can measure the proportion of parent and daughter isotopes in rocks now, you can calculate when the rocks were formed.
Tree ring dating offers over 1,000 years of clues in dates of artifacts from the American Southwest.Radiocarbon dating provides additional clues necessary for absolute dating.Continue Reading In the field of archeology, the term "absolute" is somewhat misleading.Chronometric or calendar dating is a better choice.With the passing of time, new strata form over them.
Thus, the date of an artifact is relative to its location in the levels.
Others measure the subatomic particles that are emitted as an isotope decays.
Some measure the decay of isotopes more indirectly.
Sedimentary rock is made of particles derived from other rocks, so measuring isotopes would date the original rock material, not the sediments they have ended up in.
However, there are radiometric dating methods that can be used on sedimentary rock, including luminescence dating.
When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.