When the organisms die, they stop incorporating new C-14, and the old C-14 starts to decay back into N-14 by emitting beta particles.The older an organism's remains are, the less beta radiation it emits because its C-14 is steadily dwindling at a predictable rate.For example, pieces of wood that date at about 6200 BC by tree-ring counts date at only 5400 BC by regular C-14 dating and 3900 BC by Cook's creationist revision of C-14 dating (as we see in the article, "Dating, Relative and Absolute," in the , not too old.Question: But don't trees sometimes produce more than one growth ring per year? Answer: If anything, the tree-ring sequence suffers far more from missing rings than from double rings.Coal, oil, and natural gas are supposed to be millions of years old; yet creationists say that some of them contain measurable amounts of C-14, enough to give them C-14 ages in the tens of thousands of years. Younger objects can easily be dated, because they still emit plenty of beta radiation, enough to be measured after the background radiation has been subtracted out of the total beta radiation. However, you now know why this fact doesn't at all invalidate radiocarbon dates of objects younger than twenty thousand years and is certainly no evidence for the notion that coals and oils might be no older than fifty thousand years.
ICR creationists claim that this discredits C-14 dating. Answer: It does discredit the C-14 dating of freshwater mussels, but that's about all.
The NERC Radiocarbon Facility (East Kilbride) is a central facility for the UK's Natural Environment Research Council (NERC), providing dating support in the environmental sciences.