|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.