Age dating equation
This volcanic episode provides an important reference datum in the glacial history of North America.
Volcanic ash Samples collected from strata in Olduvai Gorge, East Africa, which sandwich the fossil remains of Zinjanthropus and Homo habilis -- possible precursors of modern man.
The decay constants, along with their uncertainties, are readily available (I'll list some of the geologically important ones at the end of this post).
Decay constants are inherent properties of the nucleus that describe the probability that an atom will decay.
The half-life of an isotope is a more intuitive measure, the half-life is a unit of time over which half of the radioactive atoms in a given population will decay.