Carbon Dating for Dummies

Sort of like Lord Stanley's Cup, the trophy for worst hotbed of dumbassery travels from one website to another as popularity waxes and wanes. For a while, Bubblews.com held down the top slot, mainly on the strength of its vast collection of semiliterate teenagers from the Phillipines. That doesn't mean adults from North America were not represented. Take, for instance, Mary Gindling (megindling), who wanted in the worst way to disprove evolution. She did so by attacking radiometric dating in a piece she called "Archaeology: How Accurate is Radiocarbon Dating?"¹

Mary opens her exposé of the uselessness of carbon dating by telling her readers, 

"Radiocarbon dating techniques are based on the assumption that the carbon-14 content in the atmosphere is constant, which is known not to be the case."

This is pretty much true: scientists know that atomic testing beginning in the late 1940s changed the amount of C14 in the atmosphere. Likewise, variations in solar activity are believed to lead to changes in C14 production. Mary does not, however, mention this. Instead, she goes on to list sources she believes can disturb the amount of C14 in a sample:

"Localized events such as forest fires and volcanic eruptions can add large quantities of Carbon-14 to the atmosphere while other natural phenomena, such as the relatively low oxygen levels found at higher altitudes, might reduce the concentrations of carbon-14 along the tops of mountain ranges."

Huh? C14 is not a naturally-occurring isotope: it's created in the atmosphere when a passing gamma ray converts an atom of nitrogen 14 into an atom of carbon 14 by turning one proton into a neutron. That doesn't happen in volcanoes or forest fires. It also has jack to do with oxygen levels. But wait, there's more!

"Another factor which might affect levels of Carbon-14 in the atmosphere is population density. Highly populated areas certainly produce more carbon as a by-product of daily life. Cooking fires, slash-and-burn agricultural techniques, and many manufacturing processes will produce high levels of carbon. Densely populated areas obviously would produce more carbon than sparsely populated areas."

Now she's claiming that cooking fires generate C14? What a dumbass! More stupidity ensues:

"Another problem is that radiocarbon dating is only valid to around 35,000 or 40,000 years ago. Anything earlier than that cannot be measured by radiocarbon methods, and if an attempt is made to inadvertently measure an older artifact, the results must also inevitably be skewed."

First, the upper limit is over 50,000 years, not "35,000 or 40,000." And that upper limit is a function of the half-life of C14, meaning that the quantity present in a sample is too small to measure after 50K years or so – the results wouldn't be "skewed," you wouldn't have results, dumbass. It takes only a moment to realize that Mary Gindling is a climate-change denier whose skepticism is Bible-based. Her problem, at least in her Bubblews post, is that she's conflated radiometric carbon with carbon dioxide and attempted to use climate-change denial arguments to deny the validity of radiometric dating. What a remarkable feat of dumbassery, even for a Dumbass of the Day!

¹ Bubblews is long gone (no loss...), but Mary's article can still be found using the Wayback machine at archive.org. Its URL was   bubblews.com/news/968433-archaeology-how-accurate-is-radiocarbon-dating

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