Monday Minute: Radiocarbon Myths from a Creationist Who Understands Radiocarbon Dating

There are many laws that govern the peculiarities of everyday life, of which Murphy’s Law is the best known. But in my engagement with those teetering within the creationism debate, I’ve discovered a new pattern of behavior that perhaps deserves its own name. Let’s call it “Libby’s Law”. Simply put, the longer one discusses the age of the Earth, the more likely a flawed statement about radiocarbon dating will steer the conversation into futility.

Radiocarbon dating is relatively easy to visualize and understand on a basic level, unlike many other methods in geochronology. The atmosphere contains trace amounts of radioactive carbon (14C). Plants absorb that carbon through photosynthesis, and animals via plants. When they die, however, the radioactive carbon decays at a known rate. Measuring the ratio of radioactive to stable carbon, we can estimate the age of carbon-bearing samples.

On the other hand, the technical details of radiocarbon analysis are extremely difficult to understand. The process of sample preparation and analysis depends on the technique (gas proportional counting, liquid scintillation, or accelerator mass spectrometry, for example), of which each has its own limitations and potential for error and uncertainty. Mathematical corrections are complex, and the reliability of dates can even vary between samples. Hence geochronologists have devoted entire peer-reviewed journals to addressing the many challenges that arise.

In recent years, creation ministries have taken full advantage of both factors. They present radiocarbon dating as straightforward and easy to understand, while building their case on technical discussions that are simply inaccessible to the non-specialist reader. According to organizations like ICR, CMI, and AiG, ancient samples of coal, graphite, diamond, petrified wood, and even dinosaur bones have been dated confidently to only 30–70,000 years old, rather than the tens of millions of years assigned to them via other techniques. What a discrepancy! It’s abundantly clear why apparent contradictions involving the radiocarbon method are the preferred soundbite references for the everyday Young-Earth Creationist.

While I’ve written at length on how creation ministries deviously misrepresent the radiocarbon method to support their claims, I’m going to do something completely unexpected and refer you instead to a rebuttal published by…well, the Institute for Creation Research! Therein, Dr. Gerald Aardsma explains six common myths regarding radiocarbon dating. In response to the myth that samples of coal have been dated to only 20,000 years, he writes:

It is easy to contaminate a sample which contains very little radiocarbon with enough radiocarbon from the research environment to give it an apparent radiocarbon age which is much less than its actual radiocarbon age. For example, a sample with a true radiocarbon age of 100,000 radiocarbon years will yield a measured radiocarbon age of about 20,000 radiocarbon years if the sample is contaminated with a weight of modern carbon of just 5% of the weight of the sample’s carbon. It is not too difficult to supply contaminating radiocarbon since it is present in relatively high concentrations in the air and in the tissues of all living things including any individuals handling the sample. For this reason special precautions need to be exercised when sampling materials which contain only small amounts of radiocarbon.

Now, this article was published originally in 1989, which means two things. First, Dr. Aardsma’s statement that “no reliable historically dated artifacts exist…older than 5,000 years” is no longer true. Multiple collaborative studies have independently confirmed radiocarbon dates up to ~50,000 years. Secondly, Dr. Aardsma is writing prior to the time when creation ministries began to manipulate radiocarbon results to reinforce their position. Instead, he takes the more honest approach, which is to say that since radiocarbon dating yields ages often exceed 6,000 years, YEC’s can only assume that the Flood somehow distorted the carbon cycle and undermined the method’s assumptions.

From now on, whenever you encounter the claim that radiocarbon dating supports a young Earth, I hope you remember Libby’s Law.

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5 responses to “Monday Minute: Radiocarbon Myths from a Creationist Who Understands Radiocarbon Dating

  1. What about the artifacts and fossils known to be only a few hundred years but, when tested via radiocarbon dating, were dated at millions of years? You seem to know the research, so I’m assuming you know about these, but if you don’t, I can find them and link them here. There was a fedora found in a mine shaft that collapsed, a shoe, and there was also one from the recent eruption of Mt. St. Helens. Do you know anything about this? 🙂 I’ve dabbled into this a little bit, but obviously don’t know enough. Chemistry and stuff like this fascinates me. 🙂

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  2. Hi Mercy, thanks for the question. I am familiar with the examples you raised, but there are no samples that could be dated via radiocarbon at millions of years. The radiocarbon method gives dates only back to 50,000–75,000 years at most. Feel free to link the examples if you think I’m mistaken.

    In any case, there are modern organisms, shells, and the like, which are dated by radiocarbon to several thousand years old. The reason is that they obtain their carbon partly from dissolved limestone in the oceans, and the limestone itself is millions of years old. If you combine a sample that is 0 years old with one that is 1 million years old, you will get a date somewhere in between. The same could be true for shoes and such in mine shafts—you need to know what is actually being dated.

    As far as Mt. St. Helens, there were samples submitted that yielded dates of 0–2 million years old. The volcanic glass and low-temperature minerals were dated at ~0 years old, because they formed during the eruption. However, several high-temperature minerals were dated at 1-2 million years old, most likely because that was their true age. 🙂 They were not formed during the eruption, but long before. This is common in volcanic systems.

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    • Thanks for the response!
      Okay, I’m confused. I have heard before that radiocarbon dating can only go back so far, but then, how do they date the rocks, like the one you said from Mt. St. Helens that they dated back up to 2 million years? Where do they get that number if radiocarbon dating only goes back so far? Is there another method?
      Also, if things can be mixed like that, how do you truly know the age of anything? For example, when dating bones and stuff, how do they know that they’re dating the BONES, instead of the rocks around them? What if the rocks are old, but the bones just took on the limestone of the rocks and are actually really new, lol?
      In short, it sounds like an unstable method of dating. Is it? If it can get mixed up so easily, how do they really know the age of anything they date?
      That explanation for the erupted rock makes sense, thanks! But again, if it only goes back so far, how do they know? 🙂 Thanks for the chat, this is fun! 🙂

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      • Hi Mercy,
        To answer your first question, yes, there are many methods to date rocks that don’t involve carbon. For the Mt. St. Helens rocks, the Potassium-Argon method was used (which, by the way, is not typically used for young rocks; it works much better for very old rocks). Collectively, these cover the entire range of possible ages of things, even to many billions of years old.

        How do we truly know the age of anything? Well, you simply need to know what you are dating. There are ways (e.g. chemical analyses) that help us determine if we’re actually dating bones or some contaminant, for example.

        When those precautions are followed, the method works extremely well. For example, when lake sediments are dated, the layers get increasingly older as you dig deeper beneath the lake, just as we might expect. If there is any doubt, however, other methods are available to analyze the same material. When multiple methods give the same answer, we have more confidence that the answer is correct.

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