Not too long ago, I ran across a creationist argument that I found particularly galling. Briefly, some Creationists have been running around telling folks that some coals, particularly those from the western U.S., have been able to be radiocarbon dated. These coals, (most from the Bighorn Basin in WY) were deposited in the Paleocene-Eocene, ~65-50 Million years ago (Mya). Coal deposits are formed by the accumulation of biomass (often plants) and its subsequent burial and compaction. In the case of the Bighorn Basin coals, these were deposited in extensive swamps that persisted for some time.
The Creationists’ point is that GEOLOGISTS say these deposits are many millions of years old, BUT if they can be radiocarbon dated, they must have 14C (carbon’s radio-isotope). 14C has a half-life of ~50-60,000 years (for more info on radiocarbon dating, I suggest going to http://www.c14dating.com/); so, to the Creationists this PROVES that geologists are morons and a magic man in the sky made everything.
Like everything Creationists say or think or believe, they have got this one all wrong. It is true that some coals do have some 14C in them, but the ORIGIN of that 14C is not necessarily related to the time of deposition for that coal. In other words, that 14C has been made in place (in situ in the science parlance) within the coal, a longtime AFTER its burial and formation.
A paper by David C. Lowe (1989, Radiocarbon v. 31, n. 2, p. 117-120: a .pdf can be found at http://digitalcommons.library.arizona.edu/index.php/objectviewer?o=http://radiocarbon.library.arizona.edu/Volume31/Number2/azu_radiocarbon_v31_n2_117_120_v.pdf) was the first (to my knowledge) paper to raise this question, and provide a plausible explanation for the discrepancy. Lowe shows how bacteria and fungi living in the coal substrate can degrade lignite as part of their own biological activity; where there is life, there is radioactive carbon being formed. Lowe shows how formation and deposition of just 0.1% by weight of modern 14C could produce a date of 45,000 years. Additionally, Lowe mentions how the decay of uranium/thorium in the coal could also lead to the production of radium, which in its decay could produce 14C.
So, once again, the whole Creationist argument is a tempest in a teacup; scientists knew about the finite 14C age dates derived from older coals, and have subsequently explained their occurrence through a very parsimonious mechanism. Instead of having to throw out the whole body of geological observations, theory, and knowledge we’ve accumulated over the past two hundred years, we were able to provide conclusive evidence for how old coals could exhibit young dates.
The really ridiculous thing is how intellectually dishonest these Creationists are. First and foremost, whichever bible-thumping troglodyte first put forward this “evidence” for creationism MUST have run across Lowe (1989). So either they didn’t bother to actually READ the paper (where the young age is explained as an artifact of modern processes) or they IGNORED that part and tried to manufacture a controversy.
Additionally, the entire Creationist argument hinges on the ACCEPTANCE of radiocarbon dating methods, which still showed the carbon dates to be 45000 years. That’s a bit older than 6000 years, fellas. On one hand, these people will tell you that radiometric dating techniques are all nonsense. Then, on the other hand, they’ll bring up this little gem, and try and tell you how the radiocarbon dates show coals are much younger. You can’t have it both ways, folks.