# 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.