Mathematically, P = Po exp(-lambda T), where lambda = the decay constant and T = the period of decay. a zero initial number of D atoms, where P(or D) = the current number of P(or D) atoms, it follows that the age of a rock or mineral is computed as T=(1/lambda)ln(1 D/P).
Using radiometric techniques, the oldest dated minerals (4.0 - 4.2 billion years) are zircon crystals found in sedimentary rocks in western Australia.
Most people accept the current old-earth (OE) age estimate of around 4.6 billion years.
This age is obtained from radiometric dating and is assumed by evolutionists to provide a sufficiently long time-frame for Darwinian evolution.
These estimates give 4.4-4.5 billion years for moon rock, and 4.54 billion years for iron metreorites.
These techniques utilize the physical parameters of the earth, such as ice cores, annual lake sediments, and astronomical cycles.
Radioactive parent (P) atoms decay to stable daughter (D) atoms e.g.
the carbon isotope C-14 decays to nitrogen-14 and the uranium isotope U-235 decays to the lead isotope Pb-207.
Similarly, annual lake sediments can be used to estimate relative age and conventional interpretation for the Green River varves suggests they have been formed over some 20 million years.
The crucial point here is: if YE theory can be established scientifically, then macroevolutionary theory falls!
Accepted Dating Methods Here we outline some dating methods, both absolute and relative, that are widely accepted and used by the scientific community.
And OE Christians (theistic evolutionists) see no problem with this dating whilst still accepting biblical creation, see Radiometric Dating - A Christian Perspective.
This is the crucial point: it is claimed by some that an old earth supports evolutionary theory and by implication removes the need for biblical creation.