Radiocarbon in Coal?

Several years ago, the creationist RATE Team obtained multiple coal samples from different coal seams all over the US and submitted them to the now closed Canadian IsoTrace Facility for radiocarbon dating. Interestingly, the measured 14C activity of those coals was quite high compared to the laboratory’s ‘standard’ background, ranging from 0.10±0.03 to 0.46±0.03 percent Modern Carbon. Humphreys et al. (2011) believe this contradicts the notion that coal fields are millions of years old:

»How does one make sense of these 14C measurements that yield a uniformitarian ages of 40,000–60,000 years for organic samples, such as our coal samples, that have uniformitarian ages of 40–350 million years based on long half-life isotope methods applied to surrounding host rocks? Clearly there is an inconsistency.«

As it turns out, creationists are not the first to discover this problem. Scientists have known about this for decades. For instance, Vogel, Nelson and Southon (1987) used coal as background material and soon recognized that the resultant 14C ‘ages’ seemed anomalously young. The authors suspected persistent contamination, however the source of that contamination remained unknown. A few years later, Lowe (1989) proposed a solution to this paradox, arguing that microbial and fungal activity could be responsible for the presence of radiocarbon in coal. This is not a far-fetched notion as various kinds of bacteria and fungi have been demonstrated to occur in coal, either feeding on the coal itself or on pyrite inclusions.

John Baumgardner, a member of the RATE committee, tried to refute this by pointing out that there was no way these microbes could possibly add any radiocarbon to the coal if they were feeding on it. This, however, is easily answered. First of all, these microbial species do not get all of their carbon from the 14C-depleted coals. Indeed, they have been shown to incorporate atmospheric carbon during their growth as well. This is made possible by the fact that coal deposits become exposed to atmospheric conditions after the onset of mining operations, which commonly results in extensive wheatering of the coal (Mitchell & Mathews, 2013).

Secondly, some of these microorganisms may not even feed on the coal at all. Instead, they may simply derive from surface soils. This possibility was explored by Farrell & Turner (1932). They tried to isolate bacteria from anthracite samples recovered at Pimrose vein, Pennsylvania, some 300 to 400 feet underground. Interestingly, bacteria were found in all cases where the coal had visible cracks. Moreover, bacterial species found in the coal were also very common in surface and mine waters, suggesting that these microbes reached the coal via water penetration:

»Pennsylvania anthracite from the Primrose vein contains no bacteria other than common living forms which have found ingress through fracture cracks communicating with surface water and air.«
~ Farrell & Turner, 1932 (p. 162)

Obviously, infiltration of such bacteria would add some radiocarbon to the coal. In my opinion then, the occurrence of measurable C14 in coal does not in any way imply that these materials are young. Any YEC’s on this forum that like to use this as an argument? Seems to be a bit outdated, but evolutionist responses to this are scarce and often not very convincing, too. So I thought I write one here.


When you are discussing radiocarbon in ancient coals and diamonds, you have to account for all possible contamination vectors before attempting to claim that the samples are far younger than indicated by other lines of evidence. You can’t just dismiss contamination as a “rescuing device” as YECs generally do; to do so is to insist that the basic rules, standards and best practices of measurement and laboratory technique do not apply to you. Furthermore, you can not just take one possible contamination vector in isolation and argue that it doesn’t fully account for the reported levels. You must add up the possible contributions from all plausible contamination vectors together.

There are several different possible contamination vectors besides in situ contamination and instrument background. Contamination can also be introduced in excavating the samples, in storage and handling, or in sample preparation. This can be very difficult to avoid; researchers need to exercise great care and attention when handling and preparing samples, and analysing particularly low levels of radiocarbon (ages greater than about 35,000 years) even requires specialist laboratory facilities with shielding to guard against cosmic rays that might interfere with the results.

It is also important to note that contamination levels can vary widely. Every step in sample preparation will introduce modern carbon to the samples, typically in the 0.14-0.25% range. Given that multiple steps of preparation are involved, levels of up to 0.5% modern carbon are almost certainly due to contamination. Furthermore, the wide ranging variation in contamination levels mean that you can not just account for it by subtracting a “standard background”; this approach would either fail to account for most of the contamination, or else end up with negative amounts of “intrinsic” radiocarbon, which would of course be absurd.

You must also realise that there may be other contamination vectors that have not yet been fully studied. While these are not likely to be large, they are almost certainly the correct explanation if the discrepancy is comparable to the amount of contamination that can be accounted for.

The RATE project team might have found something warranting attention if they had reported consistent levels well in excess of the sum total of known, measured, and plausible contamination vectors. Levels of 5% modern carbon across a wide range of samples might warrant attention, especially if they clustered tightly around that figure. Levels of 0.5% or less, with a wide ranging spread of results up to that figure, on the other hand, do not.

Note that there is nothing “evolutionist” or “uniformitarian” whatsoever about any of this. These are simply basic principles of quality control that apply to every area of science, whether they have anything to do with biological evolution or not.


How does one make sense of these 14C measurements that yield a uniformitarian ages of 40,000–60,000 years for organic samples, such as our coal samples, that have uniformitarian ages of 40–350 million years based on long half-life isotope methods applied to surrounding host rocks? Clearly there is an inconsistency.

What part of the calibration curve being limited to 55,000 years (apart from contamination issues) does Humphrey not get? My take is that the real purpose to inject doubt onto measurements which are highly robust, such as the tree ring calibrations and varve cross checks. What we know for a fact is that coal is a whole lot older than the useful range of 14C dating.

Where there exists generous sample availability, appropriate date range, and easily controlled contamination concerns, such as tree ring confirmation, cross check of varves, and early dynasty Egyptian artifacts, carbon dating is met with ridiculous YEC skepticism. Then, where there exists far too insufficient sample, completely inappropriate date range, and contamination to be expected, all of a sudden creationists turn into insistent fans who consider protocol requirements to be “rescuing devices”.

At that age range, it is almost certain that AMS dating is being applied, so cosmic rays would not interfere.

Comments @PaulGiem ?
From the footer of the Humphrey’s article referenced in the OP…
"We would like to thank Paul Giem for the helpful input he provided in this project. "


Source: this Talk Origins article

R5. This is similar to an argument put out by Harold Slusher (1981, p.45). Dr. Hovind adds the bizarre claim that something can’t be measured accurately to seven decimal places. Such nonsense is answered by Dr. Dalrymple, an expert in radiometric dating, who noted that: “Modern counting instruments, available for more than two decades, are capable of counting the C-14 activity in a sample as old as 35,000 years in an ordinary laboratory, and as old as 50,000 years in laboratories constructed with special shielding against cosmic radiation. New techniques using accelerators and highly sensitive mass spectrometers, now in the experimental stage, have pushed these limits back to 70,000 or 80,000 years…” (Dalrymple, 1984, pp.86-87).

1 Like

Dalrymple is certainly authoritative concerning dating, so I would not challenge his statement here. I would note, however, that this dates back to 1984, and modern labs have all been AMS from about Y2K. It must have been painstaking work to shield samples and count clicks, and I’m pretty impressed that decent results were obtained from radiometric at all.

Can you go back 80,000 years? In principle, I expect yes, but everything would have to be consciously optimal and the error bars significant. More routinely, a facility like the Beta Analytic AMS lab states a detection limit of 47,000 years, 47K meaning that or any amount older. Past that age, their own cross checking with other labs has been such that they will not quote finite ages greater than 43,500 ybp. So that is one boots on the ground perspective. Forty Three thousand years is still not much comfort to YEC.


I’m neither a geologist nor a physicist, so I can’t speak to the relevance of this phenomenon in explaining C14 contents in coal. But there has been studies done that show there is non-neglible underground neutron radiation from heavy elements naturally found in Earth’s crust, that result in measurable C14 levels in petroleum. I wrote a post about this here about 2 years ago when a similar topic was discussed:

It seems to me if underground neutron radiation can generate measurable amounts of C14 in petroleum, it can do so in coal.


I recall reading that samples have to be specially prepared to avoid/remove contamination. It may only apply to certain types of samples, but I have now idea about the specifics.

You may appreciate this video walkthrough of 14C sample prep. The production value is not glossy, but it is very informative as to work-a-day in the lab. It is easy to tell that the skill of the technician would matter in obtaining reliable results.


Thanks for that. I’d seen it a couple of years ago, but forgotten most of it.

She mentions other videos, but I can’t find them?
[edit] nevermind, I think I have it.

This is as close as I could find, but not a direct follow-up video.

This has the lovely Carley Crann again, and the particle accelerator, but no mention of the previous video.

1 Like

Thanks for that – that definitely gives an informative look at the processes involved in sample preparation. With all the different steps involved, it’s impressive that they can get contamination down to levels as low as 0.5% modern carbon.

This is a side to science that I’m pretty sure a lot of radiometric deniers haven’t a clue about. A lot of the time, I get the impression that many of them don’t even realise that there’s actual lab work involved.

1 Like

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.

RonSewell (C3),

Thanks for inviting me in. I’m sorry this is so late, as I have been working especially hard during the COVID era (several of our doctors have retired or cut back, and one died of COVID), and have also been spending time with the isochron/mixing line thread.

Ignostic (C1) outlined the problem fairly well. He notes that coal has been noted to have radiocarbon in it, that seemed beyond what would be expected for laboratory contamination. His references are accurate, although the major thrust of Lowe’s article was that one should not use coal because it contained radiocarbon. The proposition that fungi in particular, but also bacteria, might have contributed carbon-14 to the coal was an attempt to explain why coal would have the observed carbon-14.

I’m not sure what point is being made by reference to extensive wheatering (presumably weathering) of coal. As I read the article by Mitchell and Matthews, it seemed that some samples were taken fairly rapidly from the mines, made into samples under an inert atmosphere, and then stored in drums filled with slightly pressurized argon. Reading the original Baumgardner chapter (2005– , pp 605, 606), it appears that these drums is where the RATE group got their coal. Weathering should not be a problem.

As far as microorganisms being washed in, I agree that Farrell and Turner found apparently fresh organisms in coal. But bacteria were not everywhere. As they noted on p. 160,

The absence of bacteria in the samples from the sixth level west is consistent with the fact that this coal was very compact while the coal from the sixth level east was filled with minute fracture cracks.

We’ll come back to this point later.

jammycakes (C2), as we have already discussed in another thread ( Paul Giem: Isochron Dating Rocks and Magma Mixing - #99 by RonSewell ),

It is not true that “every step in sample preparation will introduce modern carbon to the samples, typically in the 0.14-0.25% range.” First, that value is for oxidation of a sample and then reduction, which is multiple steps. Second, in the best labs, contamination in all of those steps can be gotten easily below 0.1%, and Baumgardner et al. (at my urging) used one of the best labs. Third (and this is not in the other discussion), if this was all laboratory contamination, Lowe would not have singled out coal as being unreliable. He would have had to say that everything is unreliable. And finally, two of the researchers who know the RATE group data the best both agree that laboratory contamination is not the answer for their data. It is important enough to repeat here:

Kirk Bertsche ( RATE’s Radiocarbon: Intrinsic or Contamination? ) has stated,

While this conclusion [laboratory contamination] explains the higher values for the biological samples in general, it does not account for all the details. Some biological samples d* have radiocarbon levels not explainable by sample chemistry. These samples are mostly coals and biological carbonates ….


Unlike the literature values, Baumgardner’s coal samples do show significant radiocarbon above background, inviting explanation.

(italics his). He blames the carbon-14 found on “ in situ contamination”, but he at least agrees that it is not just laboratory error.

And Harry Gove, as summarized by Kathleen Hunt ( Carbon-14 in Coal Deposits ), stated:

The short version: the 14C in coal is probably produced de novo by radioactive decay of the uranium-thorium isotope series that is naturally found in rocks (and which is found in varying concentrations in different rocks, hence the variation in 14C content in different coals). Research is ongoing at this very moment.

Note that they have different explanations for the data, which may or may not be correct singly or in combination, but they both agree that there is real carbon-14 in coal. In other words, they agree with Lowe.

RonSewell (C3),

You are correct that AMS dating is being applied, and that cosmic rays (which are a major problem with decay counting) do not interfere significantly.

jammycakes (C4),

I have trouble standing behind anything Kent Hovind says unless it can be independently verified.

RonSewell (C5),

You can go back to 80,000 years under very special circumstances. That is a carbon-14 level of 0.005 pMC, and was done by Taylor and Southon in 2007 on a diamond (Available at Use of natural diamonds to monitor 14C AMS instrument backgrounds - ScienceDirect ). If one is using 50 micrograms of a target, one can contaminate it with modern carbon at the level of 2.5 nanograms of modern carbon (actually ~2.3 ng, as we are now at ~110% modern carbon since the atmospheric nuclear bomb tests) to produce these results, and I think anyone will concede that it is possible, if not highly probable, that we are dealing with contamination here. Well, maybe not some creationists, but they should.

However, that does give you a good idea of what is possible with modern techniques. There was a set of experiments done on subfossil wood dated at 2 million years. Let me quote from my 2001 paper ( Geoscience Research Institute | Carbon-14 Content of Fossil Carbon ):

Perhaps the most interesting experiment was reported by Kirner et al. (1997). Part of the background is as follows: R. E. Taylor was aware that short-age constant-decay theories predicted that there should be >0.005 pmc in fossil carbon (Giem 1997a, p 180-187). Taylor believed that he should be able to obtain 14C/C ratios lower than those commonly published, and that could possibly match or even surpass those obtained from graphite. The results his group obtained include several measurements with an average of 0.162 pmc. The lowest value they obtained was 0.056±0.004 pmc. [[8]]( Their conclusions were that the data were best explained as the sum of a constant amount of contamination by modern carbon regardless of sample size, plus a constant proportion of carbon-14 equivalent to 0.12±0.02 pmc. The constant proportion of carbon-14 "could arise if our wood blank was not truly 14C dead either due to a finite age or the result of the presence of residual contamination not removed by chemical treatment.”

So our best information is that it is not just coal that has the problem of residual radiocarbon. This radiocarbon either had to be contamination in situ, or nuclear synthesis, or both, or some of it is actual residual radiocarbon, which has implications for age. Can anyone give any estimate for the first two? Or can anyone suggest experiments to differentiate between the three? For example, could one test for either bacteria themselves under a microscope, or grow bacterial cultures in various parts of a coal seam and see if their radiocarbon levels correlated with the bacterial/fungal burden?

jammycakes, you say (C11),

This is a side to science that I’m pretty sure a lot of radiometric deniers haven’t a clue about.

Perhaps, but not all. I’ve taken a tour of the lab where the videos were made, among other labs, and before going to medical school I ran a lab doing radioimmunoassays for aldosterone. I’m familiar with crazy quirks, like our lab could only use methanol for paper chromatography (yea, it was that long ago) from Mallingkrodt; methanol from all the other manufacturers we tried would not give us good results. This may explain why I won’t discount laboratory contamination as an explanation without convincing evidence that it is not the whole explanation for the radiocarbon measurement in question.

1 Like

Sorry to here this @PaulGiem.

Total contamination, Paul. Total contamination.

You MUST fully account for both laboratory AND in situ contamination. You CANNOT claim that they falsify other radiometric data by several orders of magnitude until you have satisfactorily done so.

In any case, there is a difference between “multiple” in the sense of the relatively simple matter of just oxidation and reduction, and “multiple” that includes all the additional steps involved in extracting cellulose from wood or collagen from bone on top of that. To claim that you can “easily” get below 0.1% for the latter more complex case just because you can “easily” get below 0.1% for the former case is an equivocation that is simply not justified.


I would maintain the laboratory contamination, or more broadly, overall laboratory and instrument limitations, could in itself plausibly account for end results indicating 14C. For the moment, however, I am going put that aside to focus on in situ and sample collection contamination.

To recap the central theme, the standard narrative is that coal formed from deposits of biomass back in deep time, and therefore any 14C that was originally present should have decayed away long ago. It may seem reasonable to assume that coal, once sequestered underground, would be isolated from the outside world, but it is increasingly clear that is unlikely, as I posted here.

In light of this, let us consider the procurement of coal samples referenced in the Baumgardner study.

The coals in this bank are intended to be representative of the economically important coalfields of the United States. The original samples were collected in 180 kg quantities from recently exposed areas of active mines, where they were placed in 115 liter steel drums with high-density gaskets and purged with argon. As soon as feasible after collection, these large samples were processed to obtain representative 300 g samples with 0.85 mm particle size (20 mesh). These smaller 300 g samples were sealed under argon in foil multi-laminate bags and have since been kept in refrigerated storage at 3°C

Nothing in that statement is false, but let us take a deeper look as to the purpose of the DOE sample database. First, the above management procedure including foil bags was developed because there was found to be unacceptable deterioration under the previous regimen. While they were satisfied with the new sample preservation:

Foil laminate bags purged with argon gas and stored under refrigeration were shown to perform well in preserving the properties of the coal samples.

…performing well does not mean perfect, as the DOE testing itself demonstrates. The level of preservation, however, is good enough for purpose, so job done. And the purpose is:

to ensure the availability of well characterized, high-quality coal samples for public and private coal research.

The public and private research anticipated is characterized by the tests the DOE itself runs - ASTM procedures, proximate analysis, gieseler plastometry, and sulfur forms. What these have in common is that they are industry specific tests for concerns particular to the usage of coal. All coal, whether metallurgical or thermal, is mined to be burned to CO2 and dumped to the atmosphere we breathe. Customers are concerned with the efficiency of combustion which can vary widely with water content, amount of ash they have to contend with, keeping within sulfur pollution allowances, and these tests, sample benchmarks and preservation, revolve around those sorts of issues. Notably absent from industry concerns are implications of AMS carbon dating for Noah’s Flood.

Now if you are going to embark on this ill conceived quest to find 14C in coal, you have to obtain samples from somewhere, and the DOE bank is as good a place as any, but that demonstrates just how difficult, really, the task of preventing contamination is. While long term storage in purged argon filled bags is great for industry tests, the collection and sampling does not preclude contamination for trace amounts of 14C.

Collection was undertaken from active sections of mines in order to obtain fresh, recently exposed coal.

Note the term exposed. How exposed is seen from the following various collection reports:

It was collected from a surface mine on … in multiple cuts from an automatic sampler on an overland conveyor belt system. — It was later determined that the coal was somewhat oxidized prior to collection. — The coal had been exposed less than two days; block samples were also collected. — The coal had been exposed approximately 20 hours prior to collection of the sample. — The coal had been exposed less than two days prior to collection.

To get an idea of what a day or two of exposure in a coal mine might entail, just take a look at pictures of miners after a shift. Black lung disease has been a historic bane. Bioslime coats timbers and shaft walls, and contributes to dangerous methane build. Dust is everywhere. These factors are better controlled in modern mines, but that is comparative. Contamination of at least trace amounts of 14C is probably inevitable in these conditions. Then afterwards, when the sample drums arrive for processing, the coal is crushed down to mesh size, allowing for another full on exposure to 14C.

But even prior to exposure at the mine, it is far from likely that the only carbon present is from original plant material. Coal is not isolated from water ground flow which supports a rich biome. Sample DECS-1 contained 30% water, DECS-11 Beulah 33%, DECS-15 Lower Sunnyside 3%, DECS-25 Pust 35%, all samples had water content ranging from 2% to upper 30%. While it could be argued that water is trapped, typical hydrology suggests that aquifers are part of a cycle in contact with the surface.

Given the hydrology of coal deposits, and the handling of samples, the results of 14C analysis, in my mind, actually lend support to the antiquity of coal. If the original carbon content of the material which turned to coal is radiocarbon dead, trace amounts of contamination both prior and subsequent to mining exposure would be expected and would be consistent with old but finite carbon dates. In view of all this, I find the conclusions of the Baumgardner study unjustified, to say the least.


EDIT: Typo’s. Added link to Baumgardner study: 14C Evidence for a Recent Global Flood and a
Young Earth.


Visualizing the decay curve may help.


With a half life of 5,700 years there would be just 0.8% of the original 14C after 40,000 years. Once you move towards the right side of that graph there will be a significant problem with contamination. All of the carbon sitting around in the environment (e.g. CO2 in the air) will have 100x higher concentrations of 14C than in the sample.


One thing that is important to note about the 14C dating of coal is that we have samples which do not contain any detectable radiocarbon. Grootes 1978 dated coal in their lab and got detectable levels, yet suspected contamination. So they took another piece of the same coal sample, ran it through an intense cleansing process it had not gone through earlier, and dated it again. The second run after this treatment got the coal to date beyond the detection limit of the procedure, indistinguishable from a sample with no 14C present in it at all. This has also occured with multiple samples of bone collagen, where six out of seven samples dated were beyond the detection limit.

These and similar findings don’t really make sense under the Flood Geology paradigm, as it makes no sense to propose that accelerated nuclear decay of 14C in some organic samples was massively faster than in others, leading to some being dead and others having remaining residual 14C in them. It does fit well with the idea of contamination being the explanation for positive readings, though.


I notice that the @GutsickGibbon YouTube channel a couple of weeks ago added a episode discussing the topic:

Radiocarbon Dating Precludes Young Earth Creationism (Diamonds, Dinos and Coal)