|AN OLD-EARTH CHRISTIAN AT A YOUNG-EARTH CONFERENCE
This is the third in a series of articles about a young-Earth creationism (YEC) conference held in Bozeman, Montana in April, 2016.
2. Does Genesis Really Matter? – Yes Genesis does matter, whether a Christian believes in a young Earth or an old Earth.
3. This article – What you haven’t been told about radioisotope dating
4. Coming in the future – Ice ages, seafloor sediments, dinosaur bones, and more.
The second presentation at the April 2016 Bozeman young-Earth creation conference was “What You Haven’t Been Told About Radioisotope Dating” by Dr. Jake Hebert of the Institute for Creation Research. I could write a rather lengthy article in response, but I will try to keep things brief. I will start my review by quoting Dr. Hebert’s closing declaration:
“No Christian should be intimidated by radiometric dating.”
This is a true statement. All truth is God’s truth, including the truths revealed in the creation. If radiometric dating works—and I believe it reveals accurate dates most of the time—Christians should not be intimidated. Geologists have known for a long time that the isotope geochemistry of Earth is complex, and that radiometric dating does not always return what is considered to be a geologically-valid result, but there is no reason for old-Earth Christians to be intimidated by discrepant dates. It turns out that “wrong” radiometric dates are often helpful, and provide additional insights into geologic history.
Before going into Dr. Hebert’s arguments, it is important to emphasize that geologists do not believe that our planet is many millions of year old because of radiometric dating. Young-Earth creationists regularly attack radiometric dating techniques, thinking that if they discredit these methods they will undermine the idea of an ancient Earth, but this is not the case. Most scientists who investigated Earth history in the late 1700s and early 1800s came to the conclusion that Earth must be far older than just a few thousand years. This was long before the discovery of radioactivity in the 1890s or the development of radiometric dating techniques in the 1900s. Most of these early geologists were Christians of one sort or another, and a number of them were quite orthodox in their theology. These early geologists—along with modern geologists—observed a rock record that tells a story. That story includes chapters that speak of processes that require lengthy periods of time, such as the cooling and crystallization of magma to form igneous rocks, weathering of rocks to produce ancient soils (paleosols) and unconformities; growth of fossil reef organisms (as well as other complete fossilized ecosystems), and transformation of rocks by metamorphic processes. Volcanoes are complex features representing numerous eruptions, coral reefs do not grow in just a few days (especially in muddy floodwaters), and many metamorphic processes involve the extremely slow diffusion of ions through solid crystalline structures. Geologists assemble the details of Earth history by the application of principles that are rooted in Christian thought: the universe is real and not an illusion, the universe is understandable, and the universe is governed by laws. Without the various radiometric dating methods, geologists would still believe Earth is ancient. What radiometric dating does is give geologists discrete ages to assign to many events in Earth’s long history, something that would be impossible to do using other techniques.
A SHORT REPLY TO DR. HEBERT’S ARGUMENTS
For those of you who do not want to wade through this entire article, here’s a summary:
- YECs like to point to instances where radiometric dating doesn’t work. Geologists know that radiometric dating sometimes gives unexpected or conflicting results, so this is nothing new. What YECs don’t tell you is that radiometric dating usually does work, and that it usually gives results that are consistent with standard geological interpretations of Earth history.
- Non-radioisotopic YEC arguments for a young Earth, such as erosion rates, sedimentation rates, or the strength of Earth’s magnetic field, are generally based on distortions or misapplications of the principle of uniformitarianism. Why use processes that have variable rates rather than a process (radioactivity) that has been observed to occur at a highly regular rate? In addition, most of YECs arguments for the age of the Earth still yield dates that are in millions of years, not just a few thousands of years.
- The results of the largest YEC investigation into radiometric dating—the RATE project (for Radioisotopes and the Age of The Earth)—actually confirm that radiometric dating is built on a firm scientific foundation. The YECs still like to point to oddities such as carbon-14 in coal (which is explainable in an old-Earth framework), but overall they acknowledge that a vast amount of radioactive decay has occurred in Earth history, that radiometric dates are usually consistent with standard interpretations of Earth history, and that geoscientists have valid means of determining whether or not parent or daughter isotopes have been added or removed from samples. The only thing left to YECs, in many cases, is the idea that the rate of radioactive decay was greatly accelerated at one or more times in Earth’s history, such as during Noah’s flood. There are a number of problems with this hypothesis, such as the amount of heat that would have been released by this million-fold increase in decay.
A LONGER ANALYSIS OF DR. HEBERT’S ARGUMENTS
Dr. Hebert had four main “reasons to be confident that radiometric dating does not prove millions of years.”
Radiometric dating contradicts common sense
Dr. Hebert mentioned a few commonly-used YEC examples of radiometric dates which do not conform to reasonable old-Earth interpretations. One of these was the study done in the 1990s by Steven Austin of the Institute for Creation Research, in which ICR submitted samples from the 1986 dacite lava dome eruption of Mt. St. Helens to a laboratory for potassium-argon dating. The resultant dates for mineral and whole-rock samples ranged from 0.34 to 2.8 million years old, even though the dacite was a product of an eruption that occurred in 1986. The YEC reasoning on this is that if radiometric dating cannot yield a “common sense” date on a sample of known age, how can scientists trust it for dating any rocks?
There are several good critiques available of this YEC argument about the 1986 Mt St Helens samples (such as this article by Kevin Henke) , so I will only summarize:
- This experiment by ICR was set up to fail from the beginning. K-Ar dating is not expected to work on samples that formed only a few years ago. The half-life of potassium-40 is 1.25 billion years. The amount of radiogenic argon-40 produced from potassium-40 in only a few years is miniscule, and so in general, standard K-Ar dating is not recommended for samples believed to be less than 2 million years old, as there is a risk of contamination from residual argon from previous samples. This problem in itself is sufficient to lead one to be skeptical of this YEC claim.
- Additional problems abound, such as the presence of xenocrysts (crystals that appear to be derived from the walls of the magma chamber or other sub-volcanic conduits rather than crystallizing from the magma itself), zoned crystals (which indicate that mineral grains crystallized in stages in the magma chamber), and presence of volcanic glass in the samples (which would have trapped much of any argon-40 that was dissolved in the magma).
Radiometric dating ages disagree with ages determined by other methods
Dr. Hebert stated that most other means of determining the age of the Earth, such as the rates of accumulation of various salts in Earth’s oceans and the decay of the strength of Earth’s magnetic field, give ages much younger than billions of years.
There are several obvious problems with this argument:
- Why would one think that processes with highly variable rates, such as erosion of continents or addition of various salts to seawater, would be more reliable geochronometers than a process with known rates, such as radiometric dating (I will address the issue of constant decay rates later)?
- Dr. Hebert used a distorted definition of uniformitarianism in his presentation. I know of no modern geologists who would say that either erosion or sedimentation occurs at a constant rate. This goes for a large number of geological processes.
- Many have critiqued YEC seawater arguments. I have written about seawater as well: Aluminum and the 100-year old oceans and The YEC “salty seawater” argument — not worth a grain of salt. There is also no clear evidence that I know of that the oceans are becoming more saline over time.
- The old YEC argument about Earth’s “decaying” magnetic field has no merit. YECs will point to the decreasing strength of Earth’s magnetic field over the past few hundred years and claim that if this trend were extrapolated back tens of thousands of years, the magnetic field would be so strong that Earth would be uninhabitable. But they have no compelling reason (other than their YEC beliefs) to plot their magnetic field strength points on an exponential decay curve. Given the fact that we know that the polarity of Earth’s magnetic field is highly variable, it is also likely that the strength of Earth’s magnetic field is also variable, and that what we have seen over the past few centuries is just variations of a cycle. We cannot go back in time and directly measure the strength of Earth’s magnetic field, but proxies (substitutes) which are measurable indicate that the intensity of the field varies rather than decays over time (see Earth’s Magnetic Field Strength – Past 800,000 Years).
I cannot think of a single geological process that unambiguously points to an Earth that is only 6000 years old. I also cannot think of a single geological process that is inconsistent with an Earth that is many millions of years old.
Radiometric ages disagree with other radiometric ages
This is the “problem” of discordant ages. Dr. Hebert emphasized two examples of discordancy: helium diffusion from zircon and radiocarbon dating of materials believed to be millions of years old.
Helium leakage from zircon
ICR’s Radioisotopes and the Age of The Earth (RATE) program studied zircon mineral grains from a geothermal well in New Mexico. The rocks have been dated at around 1.5 billion years, while the RATE team determined a helium diffusion (outgassing) age of only 6,000 years. A good critique of the RATE helium diffusion dates is given at Helium Diffusion in Zircon: Flaws in a Young-Earth Argument, Part 1 (of 2). To summarize, the YEC team used the present high rate of heat flow in this geothermal field and applied this to the entire thermal history of the area, rather than a thermal history model that takes into account the fact that these rocks have been much cooler for most of their history. Warm mineral grains lose helium much more rapidly than cool grains do. This is another example of YECs using a distorted version of uniformitarianism (by extending the present blindly into the past) as the foundation for their young-Earth arguments. In addition, the RATE team used an overly-simple model for helium diffusion from zircons rather than a more realistic model that takes into account defects in the crystal structure. All of this biased the results in favor of a younger Earth.
Dr. Hebert stated that radiocarbon dating assumes the same ratio of carbon-14 (radiocarbon) in the atmosphere for thousands of years. I was really surprised that he said this; perhaps my notes are wrong. Geochronologists have known for a number of years that the amount of carbon-14 in the atmosphere is somewhat variable, so radiocarbon dates are calibrated based on radiocarbon dates from archeological or biological samples (such as tree rings) of known age.
Dr. Hebert stated that there should be no carbon-14 in samples over 100,000 years old. He then stated that carbon-14 has been found in coal, dinosaur bones, diamonds, and petroleum, all of which are believed to be millions of years old. It is true that any traces of original carbon-14 in a sample should be gone after 100,000 years. But there are a number of perfectly reasonable ways for more recently-formed carbon-14 to be present in ancient deposits. One is by groundwater contamination, which brings atmospheric carbon-14 into underground systems. This would be particularly effective at bringing carbon-14 into coal. Another mechanism is naturally-induced nuclear reactions, in which neutrons (mostly from uranium and thorium) react with nitrogen-14 already in the samples to produce carbon-14. But the most likely source for carbon-14 in these samples is laboratory contamination. Most of the carbon-14 detected in YEC experiments has been at levels that push the limits of detection. It is impossible to completely clear mass spectrometers and other laboratory equipment of residues from previous analyses, and so chances are, virtually any sample analyzed will register at least some miniscule trace of carbon-14 whether or not there was any actual carbon-14 in the sample.
Radiometric Dating Assumptions
Dr. Hebert listed three conditions (he called them assumptions) that must be true in order for radiometric dating to work:
- No starting daughter isotope present.
- Neither parent nor daughter isotope can be added or taken away.
- Decay rate must be constant.
The first of these is true for some radiometric techniques, but not for all. In many cases, we know that there was some of the daughter isotope present in the sample when it formed. This is not a problem for either isochron dating (commonly used with Rb-Sr dating) or U-Th-Pb dating, which uses concordia diagrams. In both of these cases, the mathematics of the technique reveals the amount of daughter element that was present when the sample formed. If you disagree, then your problem is with math, not with geology.
The second condition must be fulfilled in order to determine an accurate radiometric date. Geochronologists will generally avoid samples that have obviously been altered since formation, as these are likely to have experienced gain or loss of either the parent or daughter nuclide. Instead, they know that it is best to analyze samples that appear fresh, unaltered, and unweathered. For isochron techniques, the graphs produced by the analyses will usually reveal whether any parent or daughter elements have been added or removed. Hyperphysics gives a good summary of isochron dating techniques.
The third condition—constant decay rates—must also be true in order for radiometric dating to work. YECs have spent much effort trying to demonstrate that radioactive decay has greatly accelerated in the past, and have thus far been unsuccessful. They also tend to dismiss the critique that their million-fold increase in radioactive decay during Noah’s flood would have irradiated all life on Earth, including everything on Noah’s Ark, and would have released enough heat to vaporize Earth’s oceans, and then some.
Other discordant dates, such as where K-Ar dates do not agree with Rb-Sr dates, are not uncommon in geological research, but they are also the exception in radiometric dating rather than the rule. When discordant dates do occur, geologists actually often get excited, as this may mean that more information can be learned about the history of a sample than just how old it is. For instance, when an igneous rock forms from magma, both the K-Ar and Rb-Sr clocks are set to zero. If the rock is re-heated (but not melted) millions of years later, such as by contact metamorphism, the Rb-Sr clock may keep on running, but argon may be driven out of the rock, resetting the K-Ar clock. This will result in two discordant, but highly useful, dates: one (Rb-Sr) for the initial rock crystallization, and one (K-
Ar) for the subsequent heating event. The scientist just has to be smarter than the rocks.
Evolutionists don’t trust radiometric dates either
The YEC criticism here is that geologists will throw out radiometric dates that do not meet their preconceived notions about how old a rock is. Dr. Hebert gave several examples of this. My response is that it is valid to weigh or prioritize various contradictory evidences, rather than throwing out what you know from a long list of reasons just because of one discrepant result. If geoscientists consistently got inconsistent results from radiometric dating, they would never use it. But radiometric dating usually gives results that are consistent with the order of events in Earth history that geologists have reconstructed over the past 200 years. Precambrian rocks usually have Precambrian radiometric dates, Paleozoic rocks usually have Paleozoic radiometric dates, and Pleistocene materials usually have Pleistocene radiometric dates. When “goofy” results come back from the radioisotope lab, geologists do not just throw up their arms and give up on the techniques. Nor do they throw out the geologic history of an area that is based on multiple investigations. Sometimes the discrepant result will lead to a better understanding of geologic history. At other times the discrepant result will remain a mystery, perhaps to be solved by the next generation of geoscientists. That is how science often works in a complex world.
Dr. Hebert entitled his presentation “What You Haven’t Been Told About Radiometric Dating.” What his audience needed to hear, however, was a talk entitled “What YECs Haven’t Told You About Radiometric Dating.” What Dr. Hebert did not tell his audience was that the findings of the RATE study were an implicit admission that radiometric dating works most of the time. The RATE team determined that
- A tremendous amount of radioactive decay has occurred in rocks during Earth history.
- The first two assumptions of radiometric dating are usually satisfied in geologic settings, and that it is often possible to recognize when this is not the case.
- Most radiometric dates are consistent with the order of events that both YEC scientists and old-Earth geologists agree on. Radiometric dates of Precambrian rocks are usually older than radiometric dates of Paleozoic rocks, which are usually older than radiometric dates of Mesozoic rocks, which are usually older than radiometric dates of Cenozoic rocks. Despite YECs continuing to point to discordant or discrepant dates, these are the exceptions rather than the rule.
RATE is an admission that radiometric dating works. The only thing left for YECs to cling to is accelerated nuclear decay. And their only remaining argument for the actual occurrence of accelerated nuclear decay in Earth history is that it is the only way for them to compress the clear evidence for past nuclear decay into their young-Earth timespan.
Radiometric dating is based on chemistry and physics, not evolution, naturalism, or even belief in an old Earth. There are no reasons for Christians to be intimidated by radiometric dating.
Grace and Peace
I interacted a little bit with Dr. Hebert between sessions. He is a bright, articulate individual, and was respectful of me as an old-Earth Christian.
My analysis is based on handwritten notes I took during the meetings. There is always the chance that I mis-heard or misunderstood the speaker, or mis-wrote my notes. If this is the case, I apologize in advance to the speakers.
For a much more thorough presentation of radiometric dating, see Radiometric Dating: A Christian Perspective, by Roger Wiens.
Dr. Hebert usually used the term “radioisotope dating” rather than “radiometric dating.” They are synonymous terms.
YECs are very hesitant to state that “All truth is God’s truth.” This YEC denial that all truth is God’s truth, whether revealed in Scripture or in the creation, is a denial that creation is real rather than an illusion, and has much in common with both Gnosticism and postmodernism.
Dacite (e.g. from Mt. St. Helens) is a volcanic rock intermediate in composition between rhyolite and andesite.
Dr. Hebert illustrated the conditions necessary for radiometric dating to work by describing someone peeling potatoes. If you walked in on someone peeling potatoes, could you determine how long ago they started peeling potatoes based on the amount of potatoes peeled and the rate at which they were presently being peeled?
|This is the fourth post in a multi-part review of a young-Earth creationist (YEC) presentation given by Dr. Nathaniel Jeanson of the Institute for Creation Research in Billings, Montana in November 2012.
Part 1— The Relevance of Genesis (I was in complete agreement with Dr. Jeanson). The YEC version of the scientific method.
Part 2— Hyper-rapid post-flood diversification of species. Five fossil facts that YECs think point to Noah’s flood.
Part 3 — Distortion of “uniformitarianism.” Mount St. Helens.
Part 4 — This page. Seawater. Mud sedimentation rates. Radiometric dating.
Part 5 — Dinosaurs in the land of bunnies and daisies. My question in the Q&A.
I am an old-Earth Christian and strongly disagree with much of what Dr. Jeanson presented. I believe that young-Earth creationism is neither Biblically necessary nor scientifically feasible. Dr. Jeanson is my brother in Christ, and nothing I am writing in this series should be taken as an attack on him or any other YEC believer.
There are two additional posts related to this conference. In I do have an advocate before the Father, I discuss a conversation I had with a fellow attendee at the conference. In There is more than one way to be really wrong about the environment, I critique a video that was shown promoting a radical anti-environmental documentary.
Dr. Jeanson moved on to the topic of the age of the Earth, lecturing on ocean salinity, sedimentation rates, and radiometric dating.
Seawater contains a number of dissolved ions: sodium, chlorine, magnesium, and so forth. A common YEC argument for a young Earth is that if the oceans have been in existence for billions of years, they should—in their minds, at least—contain much higher concentrations of dissolved ions (salts) than what is observed. According to the YEC argument, if one can determine how fast an element is entering the ocean, such as from rivers, and how fast it is being removed, such as through chemical reactions on the sea floor, one should be able to determine a maximum age for the oceans. Dr. Jeanson stated that the oceans could not possibly be older than 62 million years old, a number commonly given in YEC literature.
I have addressed this issue a couple times in the past (see The YEC “salty seawater” argument—not worth a grain of salt and Aluminum and the 100-year old oceans). I’ll summarize by saying:
- This YEC argument is, once again, based on a faulty application of “uniformitarianism.” Geologists do not teach that rates of geologic processes are constant, such as the rate of sodium input or removal from the oceans. Sodium input, for example, is dependent on the amount of erosion that occurs on continents. In times when oceans covered more of the continents, sodium input to the sea would have been considerably lower than at present. At times when large evaporite deposits were being formed in restricted basins, sodium removal rates would have been considerably higher.
- YECs have not demonstrated that the concentrations of various salts in the ocean are actually increasing. In fact, seawater salinity has actually decreased since the most recent glaciation. This makes sense, as the melting of tens of millions of cubic kilometers of ice would have diluted the oceans. It is difficult to determine the exact salinity of the oceans throughout geologic time, but it appears that there has been a general downward salinity trend since the Cambrian, as can be seen in the figure from Hay et al (2006) shown here.
- If one applies the YEC argument to minor elements in seawater, one comes up with wacky maximum ages for the oceans, such as 100 years for aluminum. This should raise a giant red flag or turn on flashing warning lights, as we know the oceans are indeed older than my grandparents.
Jeanson asserted that if one measures the rate at which mud is entering the ocean compared to the amount of mud that is on the ocean floor, one comes up with a maximum age for the ocean of 12 million years. Again, this argument depends on the distorted YEC definition of uniformitarianism, and ignores many factors.
Radiometric Dating — Assumptions
Dr. Jeanson began his discussion of radiometric dating by describing the 238U to 206Pb decay chain. No controversy there. Then he stated three assumptions that must be true for radiometric dating to be valid:
- There must be no daughter isotope (e.g 206Pb) at the start.
- There can be no contamination of parent or daughter.
- There must be constant rate of decay.
The first assumption given by Jeanson is not always necessary. Some radiometric dating methods can work just fine even if there was an initial quantity of a daughter isotope. A common example is rubidium-strontium dating of igneous rocks. What matters in this case is not that the rock or mineral being dated has no initial strontium, but that the magma was homogeneous in terms of its 87Sr/86Sr ratio. Being that 87Sr is formed from 87Rb, minerals in a rock with higher concentrations of 87Rb will have a greater increase in the 87Sr/86Sr ratio over time than minerals with a low 87Rb concentration. By plotting multiple analyses for the same rock on a graph, geochronologists can determine the age of the rock, even though it initially had 87Sr. This is an example of isochron dating. The mathematics behind this technique are straightforward, and rubidium-strontium dating has been used successfully many thousands of times, even though it violates the first of Dr. Jeanson’s assumptions.
In other radiometric dating techniques, we can be certain that there was no daughter when the mineral formed, without making assumptions that may or may not be true. An example is fission-track dating. A fission-track is formed when a nucleus of 238U spontaneously undergoes fission, rather than undergoing the more common emission of an alpha particle. The two newly-formed nuclei, both being positively-charged, are repelled from each other with tremendous energy, and create a trail of damage in the crystal. The number of fission-tracks formed a mineral is dependent on the uranium concentration and age; the initial concentration of fission-tracks will certainly be zero.
The second of Jeanson’s assumptions can often be tested. First of all, geochronologists recognize the importance of dating fresh, unaltered samples. Rocks or minerals that have gone through chemical alteration or weathering are more likely to have problems with gain or loss of elements. With the isochron method, if there has been a gain or loss of parent or daughter isotopes, it will be obvious on the graph of isotope ratios (see the fourth diagram on the isochron dating page). When contamination has occurred (i.e., when the mineral or rock is not a closed system), the date determined by radiometric dating is more likely to be “wrong.”
The third assumption is one that has been called into question by YECs, and there is some evidence that there can be minor fluctuations in some decay rates. There are a number of problems, however, with YEC arguments regarding decay rates. They claim, for example, that radioactive decay occurred at a dramatically increased rate during Noah’s flood. The problem is that radioactive decay generates a tremendous amount of energy, and accelerating the process to this extent would produce enough heat to boil the oceans and melt a significant portion of Earth’s crust. A second problem is that the amount of radiation released by accelerated nuclear decay would have fried the inhabitants of Noah’s ark. Not only would radiation be coming from Earth’s crust, but radiation would be coming from the million-fold increase of decay of 40K and 14C in Noah and his family; the animals, and the wood of the ark. A third problem with accelerated decay is that whatever causes this decay (neutrinos?) would have had to affect a number of very different decay mechanisms—alpha, beta, positron, spontaneous fission, and others—in exactly the same way. This is because, despite what YECs say, most dates determined by radiometric methods are both consistent and concordant. They are consistent in that they usually give results that make sense in terms of geological history as understood by geologists, and they are concordant in that different methods used on the same rocks usually give similar ages.
Radiometric dating — YEC reasons for why it doesn’t work
Radiometric dating usually works as intended by geoscientists, and gives results that are consistent with Earth history as it has been painstakingly unraveled by thousands of workers. YECs emphasize the instances when radiometric dating does not work correctly, and use those instances in an attempt to invalidate the entire method. Dr. Jeanson gave three reasons to reject radiometric dating:
- Inaccurate — Radiometric dating sometimes gives results that are clearly wrong, but YECs want you to believe this is the rule rather than the exception. Dr. Jeanson discussed volcanic rocks that are of known age, such as the dacite from the 1980s eruptions of Mount St. Helens. These rocks (or mineral and glass separates from the rocks) give K-Ar dates that range from 340,000 to 2,800,000 years, even though we know they were formed in the 1980s. It must be understood, however, that the K-Ar method cannot be used for samples less than a few hundred thousand years old. Samples younger than that are expected to have significant errors due to traces of argon in the laboratory. Jeanson went on to state that every rock of known age ends up with a goofy age when dated by radiometric dating. This is quite simply not true; one example is a date determined for the AD 79 eruption of Vesuvius (here). I could go on about xenoliths and 40Ar/39Ar dating, but will save that for another time, or you can read about xenoliths here.
- Inconsistent — Radiometric dating methods sometimes give results that are inconsistent with one another, therefore all radiometric dating is suspect. Dr. Jeanson discussed rocks that were dated at 1.5 billion years by U-Pb dating, but when dated using a YEC helium diffusion model, the age turned out to be 6,000 years. It has been demonstrated that, in the YEC RATE study which Jeanson was referring to, the YEC researchers once again applied a faulty definition of uniformitarianism, and used a simplistic model for helium diffusion in the mineral zircon. When corrections are made to the helium diffusion model, the data is much more consistent with an old Earth than with a young Earth. You can read more about it here and here.
- Impossible results — Dr. Jeanson discussed another much-publicized finding of the RATE study, and that is the existence of carbon-14 in samples that are alleged to be millions of years old and should therefore be radiocarbon-dead. In hindsight, it should not be surprising that traces of radiocarbon would be found in these substances. Not all 14C in Earth’s crust has a biological source; some will be created anyplace where a carbon-containing substance (e.g. coal, diamond) has uranium associated with it, which is not uncommon. Neutrons from spontaneous fission of 238U, for example can cause nuclear reactions in the crust that form 14C. This is insufficient to form all 14C found in coal, but there are other explanations for the bulk of that, such as contamination by organic carbon carried in groundwater. An additional problem for the YECs is contamination in the laboratory, which is especially significant given that the amount of 14C in these samples is near the lower detection threshold for the mass spectrometry instruments used.
The YEC attacks on radiometric dating probably sounded convincing to most of the audience, but are full of flaws and should not be used as Christian apologetics.