Radiometric dating is least useful for dating
In other words, half of the radioactive isotope in a sample would have decayed to Nitrogen-14 (N-14) in just 5,730 years.
C-14 dating of carbon-bearing materials is therefore limited to roughly 50,000 years.
But YE scientists point out some anomalies in relation to C-14 and a very old earth.
For instance, measurable amounts of C-14 have been found in fossil material, such as coal (traditionally Carboniferous period c300 mya).
This implies the earth is at least 20 million years old.
Astronomical cycles can also be used to measure relative age.
A young earth is considered to be typically just 6,000 years old since this fits the creation account and some dating deductions from Genesis.
Some claim Genesis in particular, and the Bible in general looks mythical from this standpoint.
A full discussion of the topic must therefore include the current scientific challenge to the OE concept.
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.