Types of relative dating methods sex dating in saybrook illinois
These isotopes break down at a constant rate over time through radioactive decay.By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined.
In many cases, however, it is possible to reconstruct the original sequence of strata so that they can be used for relative dating.
We define the rate of this radioactive decay in half-lives.
If a radioactive isotope is said to have a half-life of 5,000 years that means after 5,000 years exactly half of it will have decayed from the parent isotope into the daughter isotopes.
In the past, relative dating methods often were the only ones available to paleoanthropologists.
As a result, it was difficult to chronologically compare fossils from different parts of the world.