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This challenge is mainly headed by Creationism which teaches a young-earth (YE) theory.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.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.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.In fact, organic samples from every portion of the Phanerozoic record (spanning the last 500 million years on OE dating) show detectable amounts of C-14.The implication is that this organic material was either contaminated by new C-14, or it was buried much more recently and OE dating methods are suspect.
Using radiometric techniques, the oldest dated minerals (4.0 - 4.2 billion years) are zircon crystals found in sedimentary rocks in western Australia.
The time required for half the original number of parent atoms to decay is called the half life.
Some half-lives are listed below: It follows that uranium-lead, potassium-argon (K-Ar), and Rubidium-Strontium (Rb-Sr) decay can be used for very long time periods, whilst radiocarbon dating can only be used up to about 70,000 years. This uses a simple exponential decay formula linking the original number, Po, of parent atoms in rocks and minerals to the P atoms now present, thereby enabling an estimate of geological age.
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.