Ancient-Earth advocates don't cotton to using carbon-14 to date fossils, coal, diamonds and such because it has an upper limit of about 60,000 years according to their reckoning. Why test things that they "know" are billions of years old, since there won't be any found anyway? Arguing from their naturalistic presuppositions has hindered scientific research (such as claiming that the appendix is a "vestigial structure" leftover from our alleged evolutionary past, doing damage to people, then finding out that it's useful). What's interesting is that scientists have found carbon-14 in old materials.
Some owlhoots rush to say, "Contamination!", which not only impugns the skills of the technicians, but is also very unrealistic. Scientists at the Institute for Creation Research have been doing carbon-14 studies, and are continuing their work. The results are promising, supporting the Genesis Flood model and causing consternation for uniformitarianism. After all, long ages are vital for evolution to work, and they can't have their foundation threatened, can they?
ICR researchers continue to look for radiocarbon in ancient carbon-containing Earth materials. Archaeologists commonly use carbon-14, or radiocarbon, to estimate ages for organic artifacts. No measurable amounts should exist in samples older than about 100,000 years because radiocarbon atoms would decay into nitrogen-14 before then. However, we keep finding carbon-14 in materials designated as tens or even hundreds of millions of years old.To read the rest, click on "Carbon-Dating Fossils".
ICR’s RATE initiative (Radioisotopes and the Age of the Earth) revealed radiocarbon in coal samples and deeply buried diamonds deemed hundreds of millions of years old. Andrew Snelling later reported radiocarbon in supposedly 32 million-year-old wood from a Colorado mine3 and in a supposedly 116 million-year-old ammonite shell.