Concordance in meteorite dating: have I misunderstood Dr. Snelling?

I want to take a moment to clarify what I said in a recent post, Andrew Snelling concedes, radiometric dating of meteorites is solid, because I stumbled upon some confusion by popular YEC blogger Dr. Jay Wile. Amid comments beneath an unrelated post, Dr. Wile was directed to the link above, to which he responded:

"Not surprisingly, you are mischaracterizing Snelling on his discussion of meteorites. He never suggests that the radiometric dates of the meteorites is accurate. He only states that there is concordance... Accelerated decay would affect all isotopes in the universe, not just the ones on earth. As a result, it would be surprising if there weren’t concordance."

Presumably, by "you", Dr. Wile is referring to the author of the blog (me), rather than the kind person who linked to it. In any case, this sort of response ensures me that Dr. Wile never read beyond the title of the article. The meaning of my title is not that Snelling would openly admit to the accuracy of radiometric dating, but that he's finally run out of bad arguments with which to distract his readers and delved into the realm of 'so absurd, he may as well just tell them the truth'.

By admitting to concordance between multiple independent dating methods applied to meteorites, Snelling essentially has conceded the strongest evidence that radiometric dates for our solar system are accurate. He can pretend that an alternate explanation still exists, but as a lover of parsimony and progress, I will call the resignation when I see it.

So, I haven't mischaracterized Dr. Snelling on his discussion of meteorites. On the other hand, Dr. Wile has, in suggesting that "it would be surprising if there weren't concordance [between dating methods]." Dr. Wile strangely ignores the main 'hypothesis' of Snelling's article, which Snelling himself falsified thoroughly: accelerated nuclear decay should have affected each decay system to a different extent (depending on atomic mass and mode of decay), resulting in systematic discordance between the results. Snelling favored this explanation when it seemed to support his collection of dates from the Grand Canyon volcanics, and he devotes several plots in his most recent article to establishing that it cannot be applied consistently to extraterrestrial rocks. For this reason, Snelling relies on poor eisegesis of the Hebrew text to pull another rabbit out of the beaten hat and suggest that concordance of meteorites is a function of 'primordial creation chemistry'. I demonstrated why this ad hoc explanation would not work in my response to Snelling, which Dr. Wile dismissed without reading to maintain his reputation in the comment wars.

To accept Snelling rationalization, we'd have to assume that God rigged the isotopic chemistry of meteorites and other solar bodies, so that after X amount of accelerated nuclear decay, all solar bodies would only appear to be 4.56 billion years old, based on our knowledge of radioactive decay in the present. In such a scenario, we would expect extreme discordance among dating methods 1) if that arbitrary interval of radioactive decay were slightly shorter or longer (this doesn't work like a fast-forward button that controls only part of the universe), or 2) if modern decay rates were slightly faster or slower. Since God is the one fine-tuning the dials, it seems suspicious that he would choose the only setting that makes modern science appear successful, don't you think?

The mystery of discordance between radiometric dates for Grand Canyon samples vs. concordance of radiometric dates for meteorite samples is rather easily solved, and we need not invoke physical absurdities like accelerated nuclear decay. Samples from the Grand Canyon were collected and submitted for analysis by the RATE team; meteorite samples were collected and submitted for analysis by experts in the field of geochronology. In my review of some shady RATE team tactics, I highlighted the fact that Snelling and Austin chose highly altered samples for radiometric dating, despite their knowing full well how chemical/thermal alteration affects the model age of rocks. In other words, they attempted to rig the results. Closer inspection of their data, however, reveals that their results still supported the conventional age of Grand Canyon basalts, and no discordance really exists. A literature review of radiometric dates for Grand Canyon basalts since 1998 (when Snelling and Austin submitted their rigged selection) demonstrates that in the hands of experts, these rocks are dated consistently and precisely from one method to the next.

So which is it, Dr. Wile? Should we expect concordance or discordance between various methods of radiometric dating, and specifically why? What is the mechanism by which accelerated nuclear decay affects the U-Th and K-Ar systems by ~1–6 orders of magnitude (depending on where in the geological column the rocks are found), but the radiocarbon system by substantially less? Why do direct dating methods like U-Th and Ar-Ar, applied to single crystals, yield similar results as isochron methods like Pb-Pb, Sm-Nd, Lu-Hf, Rb-Sr, applied to multiple crystals? Why should we expect noble-gas daughter products within the U-series and K decay systems to remain trapped in the crystal structure, despite radioactive decay so intense that it could melt the whole rock?

Can accelerated nuclear decay explain the model ages of 'post-Flood' features like caves and Quaternary marine, lacustrine, and glacial sediments, which are dated at thousands to hundreds of thousands of years by a combination of radiocarbon, U-series disequilibrium, OSL, and TL methods? Of course not. Accelerated nuclear decay is nothing more than a copout, like a bottle of whiteout to erase any contrary evidence to the young-Earth paradigm. It is entirely ad hoc and lacks any physical/theoretical framework. Above all, it makes no testable predictions in real-world data. Therefore, it is below pseudoscience, which at least tends to offer arguments that sound plausible.

Many years ago, Dr. Wile posted that he gave into the notion of accelerated nuclear decay only "kicking and screaming", because he sincerely didn't want to believe that half-lives of radioactive nuclei could change. Along with Russell Humphreys' failed helium-diffusion study, Dr. Wile cites as convincing evidence a handful of papers demonstrating that under extraordinary circumstances (such as heating tritium after absorbing it onto 15-nanometer particles of titanium to invoke nuclear pairing of 3He atoms, or burying polonium inside copper metal and dropping the temperature nearly to absolute zero), the radioactive decay constants can change by a few percentage (in most cases) to as much as 300% for one short-lived, heavy isotope. As a nuclear physicist, Dr. Wile knows well that these studies have nothing to do with the science-fiction claims of the RATE team. He knows just as well that Russell Humphreys' modeling of helium diffusion in zircons fares no better, in particular because the claim is falsified by every single application of (U-Th)/He thermochronometry since the inception of the RATE team. Therefore, I do not perceive Dr. Wile as one kicking and screaming, brought in only by a wave of evidence, but as one looking actively for excuses not to trust it.

"Best evidences for a young Earth": Snelling and the ocean-sediment flux

In September, 2012, Answers in Genesis featured a review article of what they deemed the 10 Best Evidences that Confirm a Young Earth. From this list, I have already addressed #2 (Bent Rock Layers), #6 (Helium in Radioactive Rocks), and #7 (Carbon-14 in Fossils, Coal, and Diamonds) in previous articles:

• "Rock layers folded, not fractured" — or are they?
• Clearest evidence that the Earth is 6,000 years old: helium diffusion in zircons
• Radiocarbon evidence for the antiquity of the Earth

So today, I want to discuss one of Andrew Snelling's arguments from the content of our oceans that the Earth cannot be hundreds of millions of years old. Snelling presents us with two claims on his list: #1, that too little sediment is accumulated on the ocean floor, and #9, that the oceans contain too little salt. Let's begin with #1.

Evidence #1: Very Little Sediment on the Seafloor

The argument here is rather simple. Snelling cites an article by Milliman and Syvitski (1992) to claim that every year, rivers discharge 20 billion tons of sediment into the world's oceans. He further cites Hay et al. (1988) to claim that only 1 billion tons of sediment are removed by subduction of oceanic plates (and with them, marine sediments). At this rate, Snelling claims, the whole of the marine sediments on the ocean floor would accumulate in only 12 million years.

Snelling's claims and calculations are riddled with errors and what I can only deem very dishonest research. First, Milliman and Syvitski (1992) note up front in their abstract that their estimate of sediment discharge applies only to the modern period prior to human damming of rivers. Dams tend to reduce the sediment output of rivers to the ocean by mitigating floods that carry substantially more sediment. Secondly, and most important, the authors suggest that "prior to widespread farming and deforestation... sediment discharge probably was less than half the present level." In their discussion, Milliman and Syvitski (1992) estimate the total sediment discharge to the oceans was "considerably less" than 10 billion tons per year.

So already, Snelling's calculation is off by a factor of 2 or more, due to his unwillingness to read the entire article that he cited (or even the entire abstract!). Correcting the misquotation already shifts the age estimate of ocean sediments to more than ~30 million years. Granted, this number is less than 3 billion years (the estimated mean age of our oceans), but if Snelling is willing to deceive his audience by misquoting a publicly available abstract, his methods are already suspect. One should also note that of the dozens of studies regarding sediment flux to the oceans, Snelling cites only one. Why? Since Snelling published his article in 2012, estimates of sediment flux to the ocean have multiplied and improved. One of the most recent publications places a long-term estimate at 5.5 billion tons per year (Willenbring et al., 2014), which is far less than the 20 Gt/yr used by Snelling.

Uniformitarian extrapolation

Anticipating criticism, Snelling writes that "those who advocate an old earth insist that the seafloor sediments must have accumulated at a much slower rate in the past." He provides no citation for this response, presumably because his readers would never ask for one. Thus he sets up a strawman to persuade his readers that us 'old-earthers' are desperate dogmatists. In truth, the main errors (below) in Snelling's article have less to do with the actual rate of sediment flux to the oceans. Nonetheless, we should consider the way that Snelling twists uniformitarianism in his approach to persuading readers of a young Earth.

There is nothing scientific about extrapolating rates of any natural process blindly into the past. Either one should establish good physical reason for these rates never to change (as with the speed of light or radioactive decay), or one should make predictions about past rates that can be tested by historical evidence (like the kind preserved in rocks). Thus Snelling's age estimate of the oceans, based on sediment flux, remains only conjecture and is as weak as his poorly derived assumptions.

First, why should we expect the rate of sediment delivery to the oceans to have remained constant over time? Apart from human influence, natural variations in climate affect sediment delivery, because the temperature and precipitation affect rates of chemical/physical weathering. Glaciations significantly increase the sediment flux by grinding millions of tons of rock into dust and gravel, but widespread glaciation is far more common today than even 2 million years ago, and is absent from the vast majority of Earth history. Glacially and tectonically driven changes in sea level also affect sediment flux to the deep ocean, since higher sea levels reduce the area of exposed land that can be eroded into the oceans. On longer time scales, plate tectonics greatly affect the sediment flux by raising mountain ranges and deforming brittle rock formations. Today, massive mountain ranges span the whole western coasts of the Americas, and the Himalayas constitute the single largest source of sediment to the oceans. These mountain ranges are relatively young, however, so it's reasonable to conclude that sediment flux is far greater today than for much of Earth history.

Ocean sediments in the dividend: Snelling's big error

To estimate a maximum age of 12 million years for the oceans, Snelling used his sediment flux of 19 billion tons per year to determine how long it would take to accumulate 1,300 ft (400 m) of sediment, which Hay et al. (1988) take to be the average thickness of ocean sediments. However, this average thickness includes only deep ocean pelagic sediments, of which ~74% is biogenic calcite that formed in surface waters (i.e. was not carried in by rivers). Since most riverine sediments accumulate on the continental shelves, deltas, and other nearshore basins, Snelling is comparing apples and oranges to make his case. In fact, he does not even include continental shelves, deltas, and other nearshore basins in the calculation, despite that he depicts the continental shelf in his Figure 1, titled "Where is all the sediment?".

Snelling also cites Hay et al. (1988) when he claims that only 1 billion tons of sediment are removed from the oceans via subduction, but this amount only accounts for deep ocean sediments removed via subduction, so it is incomplete. Total subduction is sufficient to recycle the entire crust in 1.8 billion years (Clift et al., 2009). Snelling's calculation thus falls to pieces with very little examination.

Most of the sediment carried to the ocean by rivers accumulates in deltas and along the continental shelves. In fact, the Ganges-Brahmaputra delta accumulated up to 70 m during the Holocene alone (i.e. in 11,700 years), according to Khan and Islam (2008). Prior to dam construction, this river system also carried nearly 1/10 of the global sediment flux. The sedimentary layers in delta sequences tend to be hundreds of meters to miles in thickness, so if we are to ask "Where is all the sediment?", the first answer should be: deltas. Fjords constitute another significant catchment, and provide ~25% of recent riverine sediments (Syvitski et al., 1987), due to the efficiency of glacial ice (particularly when it melts) in discharging sediment to the oceans.

Ocean sediments in the rocks: Snelling's really big error

A bulk of sedimentary rocks in the Earth's crust have been interpreted to be marine sediment sequences. If this interpretation is correct, then nearly all of the sediment load from rivers since the beginning of Earth history is bound up in the rocks beneath your feet. Strangely, Snelling omits this massive reservoir of riverine sand, silt, and clay while determining that our Earth's oceans cannot be older than 12 million years. The sheer volume of sedimentary rock is astounding, but is consistent with the estimate by Willenbring et al. (2014) that approximately 5.5 billion tons of sediment were discharged each year into the oceans.

We can visualize this process from a cross section of just one record of nearshore deposition, which begins with the Marcellus Shale (a major source of petroleum today). Notice that the sedimentary layers thicken to the east, where the sediment source (now the Appalachian Mountains) was once located. More than a mile of sediment accumulated in this region in a few millions of years:

Image from Wikipedia commons.

Yet Dr. Snelling omits this volume of sediment from his calculation, asking us rhetorically to account for its fate. How long will YEC's continue to trust Andrew Snelling to do their research?

"A Matter of Faith": Fear Factor - 1, Academia - 0

"Which came first: the chicken or the egg? Today we'll learn that evolution has the answer!" In the upcoming film A Matter of Faith, Harry Anderson plays Professor Kaman, a popular biology professor teaching college freshman about the origin and diversity of life through something called science. In other words, he's the villain.

It happens once a year. Waves of college freshmen pour into the lecture halls of introductory courses to fulfill their 'general ed' requirements and get their first taste of university life. Back home, many a worried parent speculates about the potential dangers of releasing their grown-up children into the wild world of academia. With what will they experiment? Sex? Drugs? Majoring in theater? And to what kind of bad influences will they be exposed? Friends with poor study habits? Political liberalism? Campus dining plans?

Now, I don't mean to belittle the ubiquitous and legitimate concern that parents have for their children first entering college and/or moving out on their own. College often is a mishmash of poor decisions and moral bankruptcy—by anyone's standard—that results in a series of life lessons and nostalgic regret for the best and worst of times. Bad behavior aside, most parents (religious or not) would also prefer to see their children grow in the worldview in which they were raised, rather than abandon it for what they learned at school. Entrusting one's higher education to professors with far more academic freedom than public school teachers, therefore, is a trial of trust for any parent hoping to confirm they have 'raised their children right'.

For many families, choosing a Christian college can mitigate these concerns. The pressure to "let go of one's moral conscious" is minimized, and every professor ascribes to a statement of faith, made public by the university. While students are still exposed to all sorts of non-Christian paradigms, it is done by academics who have reasoned through the paradigms and come out the other side with faith intact. This can be a comfortable transition for students of faith into a world where critical thinking and intellectual independence are in high demand.

So the otherwise anxious parent might think, "It's a Christian college; what could my child possibly encounter that would challenge his/her faith?"

Well, for Answers in Genesis, choosing a Christian college is only the first step. Some time ago, I wrote a 3-part review of Already Compromised by Ken Ham and Greg Hall, a book that warned parents which colleges were staffed by 'evolution-friendly' faculty that rejected a young-Earth, creation science, and overly literal readings of Genesis. (In fact, some biblical professors in the sample group even rejected that Moses alone wrote the Pentateuch!) Three years later, with the upcoming theatrical release of A Matter of Faith, it appears the YEC's fear tactic for worried parents has changed very little:

In short, a father is surprised to learn that in a university biology class, his daughter is being taught the the most elegant and commonly accepted explanation for the origin and diversity of life on this planet. Who would have known? In response, a man shocked to find that real science conflicts with his oversimplified faith decides to do his own homework and, armed with strawman objections to an established scientific theory, seeks to defeat the 'already compromised' biology professor on his own turf. We'll have to wait until September 26 to find out who wins, but my money is on the guy without the Ph.D. in biology. If I'm right, the moral of the story will be that with a few hours in his personal library, any concerned father can discover what faithless academics failed to learn through 6+ years of graduate school.

So how will this story benefit Christians with children in college/high school? Does it teach them intellectual independence and critical thinking? I want to echo here the sentiments raised by John Dunne (author of the brilliant Esther and Her Elusive God) in his review of the trailer earlier this month. John writes:

"The problem that I have... is the silly appropriation of the same trope: Christians versus educators. The attitude is Christians contra mundum. Christians versus the philosophers and Christians versus the scientists. If debates are what you want, watch a real debate. Don’t watch a scripted exchange where Christians defeat fictional foes. There is nothing about this trope that is helpful; Christians should be ashamed of the anti-intellectualism on display."

As a Christian research scientist hoping to find a permanent position in academia one day, the fact that Answers in Genesis and the filmmaker are encouraging future students to immunize themselves against mainstream science is troubling to me. This sort of attitude, once hardened in the minds of zealous young Christians, is extremely difficult to crack, and it tends to leave a long-lasting imprint on the brain. Some will struggle for years trying to recover from the young-Earth molding; others will rather leave the faith altogether. In either case, the detrimental impact of Answers in Genesis on our college generations will only continue to grow so long as they're willing to resort to anti-intellectual fear tactics to preserve a failed paradigm.

Andrew Snelling concedes, radiometric dating of meteorites is solid

Figure 18 from Snelling (2014), illustrating the frequency of isochron ages obtained from the Allende CV3 carbonaceous chondrite meteorite via six independent radioisotope systems (color coded, in legend). Note the strong peak at 4.56 Ga, the conventional age of our solar system and Earth.

After years of sorting through the results of radiometric dates, all placing the age of our Earth and Solar System at ~4.56 billion years, Andrew Snelling has essentially conceded that he cannot twist isochron ages of meteorites and bulk-Earth materials into supporting his already disproven conjectures regarding accelerated nuclear decay. If you're not familiar with this claim already, Andrew Snelling and colleagues in the RATE team have decided to brush away the overwhelming evidence of an old Earth from geochronology by suggesting that at several points in Earth's 6,000-year history, rates of nuclear decay increased by a million times or more, leaving us with the false impression that geological history spans millions to billions of years instead.

Despite the obvious scientific deficiencies behind Snelling's claim (namely, that accelerated nuclear decay would obliterate all life/water/atmosphere on Earth), we should give Snelling credit for being the master of ad hoc, deus ex machina explanations so intricate, that they are rarely found outside popular science fiction writing. But since Snelling presents his claims within the cosmic fabric of this reality, you should be shocked by the level of deception that Snelling employs through propagating his message, and the level of deception that he ascribes to God, who must have tinkered arbitrarily with natural laws like a skilled, cosmic hacker, laying a trap for inquisitive scientists that dare reconstruct Earth history through natural evidence or deviate from oversimplified readings of Genesis. Regarding accelerated nuclear decay, Snelling writes:

"...changes [to physical laws governing atomic binding forces] would thus have to have affected every atom making up the earth, and by logical extension every atom of the universe at the same time, because God appears to have created the physical laws governing the universe to operate consistently through time and space, though of course He Himself is not bound by those physical laws which He can change at any time anywhere or everywhere."

 For Snelling, the philosophical possibility that God can arbitrarily change characteristics of how the universe functions has become an axiomatic point of departure to explain why both scientists and biblical scholars must be wrong about history. Snelling (2014) further writes in his concluding remarks about why meteorites may represent the 'primordial' creation material:

"Faulkner (2013) pointed out that the Hebrew word ‘āśâ meaning “to do” and “to make” is used specifically of the creation of the astronomical bodies in Genesis 1:16, rather than the Hebrew word bārā’ meaning “to create” as used in Genesis 1:1 in reference to the creation of the universe generally... Therefore, it seems entirely possible to read Genesis 1:16 as saying God used already-existing “primordial material” which He had created out of nothing at the beginning of Day One of the Creation Week (Genesis 1:1) to then fashion it into the other planets, their satellites and the stars. Most meteorites are believed have been derived from asteroids via collisions between them breaking off fragments that then hurtled towards the earth. So to be consistent, if the asteroids were also made on Day Four from this Day One primordial material left over from the making of the planets and their satellites in the solar system, then this would imply the meteorites could represent samples of this same “primordial material.”"

The implication here is that the Genesis author chose his verbs (or received them divinely) as a function of the material origins of different parts of the cosmos, rather than something of interest to the original, Israelite audience. This line of reasoning imports a rigid—and entirely modern—distinction between the Hebrew verbs in a manner that is fine-tuned to address the concerns of a 21st-century American audience. Thus Snelling's ad hoc approach to scripture resides in a symbiotic relationship with his ad hoc approach to science, each gaining traction from the other. Snelling reads what he wants to read in scripture so that he may see what he wants to see in nature. In short, he has traded truth for certainty.

Radioisotope Dating of Meteorites: I. The Allende CV3 Carbonaceous Chrondrite

Snelling's summary of radiometric dates obtained from this particular meteorite is messy, to say the least, and illustrates well why he will never be published in an influential, peer-reviewed journal. A bulk of the Answers Research Journal article consists of unnecessary background information and tedious petrological descriptions of the meteorite samples. These sections are inconsequential to Snelling's main thesis, that despite the overwhelming consistency and precision of radiometric dates (all pointing to an age of 4.56 Ga), he still won't accept that this one meteorite, let alone the universe, is much older than 6,000 years.

To preclude the most parsimonious interpretation of the data, accepted universally by research geologists, Snelling attempts to argue that the 4.56-billion-year age of the meteorite merely reflects the geochemistry of the primordial creation material. Essentially, he claims that both meteorites and the planets were derived from this primordial creation material, which consisted of all elements and isotopes created by God on Day 1. Both parent (radioactive) and daughter (radiogenic) isotopes were incorporated into the new material, according to Snelling. Then, accelerated nuclear decay affected all atoms in the universe at several stages in Earth history (defined arbitrarily by Snelling and other creationists). As a result, both meteorites and the bulk Earth contain a common distribution of isotopes from the Uranium-Lead, Lead-Lead, Potassium-Argon, Rubidium-Strontium, Lutetium-Hafnium, and Samarium-Neodymium systems, yielding a common isochron age for both meteorites and the bulk Earth. Since these model ages do not account for isotopes/elements inherited from the primordial creation material, they are not true ages, so Snelling is free to maintain his 'biblical age' of 6,000 years as an axiomatic reference.

In case you didn't follow all of that (it took me several attempts), don't worry. You need only reference Occam's Razor to understand why Snelling's conjecture is and will remain ad hoc conjecture. It is predictive of nothing, and his starting assumption regarding the age of the universe guides his interpretation of the data. This approach stands in stark opposition to conventional geochronology, which makes precise predictions that are confirmed/disconfirmed by real data.

Snelling's conclusions are scientifically meaningless, because he cannot account for the fact that these six radiometric systems yield the same age, based on decay rates measured in the present. Despite his attempt to plead otherwise (see below), the age of meteorites and the bulk Earth are obtained through independently verifiable results.

Why should all six isotope systems yield the same age if it is not real? That is the pressing question, which Snelling cannot answer, so he glosses over it with filler descriptions of the samples and discussions of Hebrew verbs.

If we apply Snelling's model to explain the radiochemistry of meteorites, then we must assume that the primordial creation material from which God made the meteorites/planets contained just the right proportion of isotopes so that after x amount of accelerated nuclear decay, all systems appeared to have aged precisely 4.56 billion years. But this is not science, and it barely qualifies as pseudoscience (which at least has the appearance of being scientific). We need a new category to account for the level of deception employed by Andrew Snelling's latest 'research' report. Can you think of an appropriate term?

Why are there isotopes?

Assumed by Snelling and all other creationists is the notion that a recently created universe should contain a wide assortment of both stable and radioactive isotopes. But why? What exactly in the young-Earth creationist paradigm would predict the existence of isotopes at all? Isotopes are not necessary to maintain life, either of plants/animals or the solar system itself. On the contrary, radioactive isotopes produce destructive heat and energy, which is the single most prominent cause of cancer, among other disorders.

In conventional science, the existence and relative abundances of isotopes are readily predicted by models of solar evolution, because stars produce elements with varying numbers of protons and neutrons by combining lighter elements of varying masses. It makes sense within this paradigm that isotopes exist in the first place, and by using isotopes as tracers for natural processes, we've made sense of the history of the universe. But I want to suggest that in the young-Earth creationist paradigm, the mere existence of isotopes (radioactive or stable) makes absolutely no sense. Did God make isotopes just to give scientists an additional tool by which to understand physical processes 6,000 years in the future? Any answer to this question by YECs will be entirely arbitrary, rendering Snelling's model of meteorite isotope systematics even more absurd.

Meteorite isochron ages using the Al-Mg, Hf-W, Mn-Cr, and I-Xe systems

Snelling makes an odd statement amid his discussion regarding the calibration of isochron ages to the Pb-Pb system (forgive the long citation):

"The other “successful” radioisotope methods are not really independent and thus objective, because they are calibrated against the Pb-Pb method (see table 1) and therefore are automatically guaranteed to give ages identical to those obtained by the Pb-Pb isochron method. Specifically, the Al-Mg method is calibrated against the Pb-Pb isochron age for the D’Orbigny achondrite meteorite (Bouvier, Vervoort, and Patchett 2008), the Hf-W method is calibrated against the Pb-Pb isochron age for the St. Marguerite chondrite meteorite (Kleine et al. 2005) and the D’Orbigny achondrite meteorite (Burkhardt et al. 2008), the Mn-Cr method is calibrated against the Pb-Pb isochron age for the St. Marguerite chondrite meteorite (Trinquier et al. 2008), and the D’Orbigny and LEW 86010 achondrite meteorites (Yin et al. 2009), and the I-Xe method is calibrated against the I-Xe age of the Shallowater achondrite meteorite (Hohenberg et al. 2001), which is calibrated against the Pb-Pb isochron age for the St. Marguerite chondrite meteorite (Brazzle et al. 1999). Thus, as to be expected, all the dates obtained by these methods which are calibrated against these Pb-Pb isochron ages all plot in the 4.56–4.57 Ga mode with the clustered Pb-Pb dates (figs 18 and 20)."

Note that missing from the list of supposedly 'calibrated' radioisotope systems are the ones I cited in the previous section to confirm that meteorite ages are independently verifiable (U-Pb, Sm-Nd, Rb-Sr, Lu-Hf, and K-Ar/Ar-Ar). The reason is that Andrew Snelling has misunderstood the application of short-lived isotope systems, such as the Al-Mg chronometer. Al-Mg chronometry cannot give you an age of 4.56 billion years, because it depends on a short lived isotope set (i.e. radioactive isotopes that decay very rapidly, and have disappeared since the early days of the solar system). Instead, Al-Mg isotopes tell us about how long it took for the cores of chrondritic meteorites (and their various minerals) to solidify after the accumulation of raw material. Of course, the Al-Mg ages must use the formation age of the meteorite, based on Pb-Pb isochrons, as their 'starting point'. Therefore, Snelling's claim that these systems are somehow calibrated to the Pb-Pb system to yield artificially consistent results is not only bogus, but completely ignorant of the basic science behind these various applications in geochronology.

Snelling showcases his stellar research in Table 1, which reports, for example, that some of the meteorite ages in his histogram were calculated through an Al-Mg isochron. He cites one paper by Bouvier et al. (2008), where he claims that Al-Mg isochron ages were calibrated to Pb-Pb ages. However, not only does the reference cited provide no isochron ages of any kind, it also makes absolutely no mention of the Al-Mg system, period.

Exhortation

Rather than wade through Snelling's repeated attempts to rationalize the success of geochronology in constraining the age of our solar system and geological history, I strongly encourage readers to recognize that Snelling has now subtly conceded the conclusion already reached by tens of thousands of his colleagues: we can pin down the age of the Earth with great precision, and it's far older than 6,000 years. Snelling's persistent trail of misguided arguments has long lead enthusiastic readers off the path of logic and evidence, perhaps to the point that these attributes of science are no longer recognizable. For this, I cannot help but to lament the loss of millions to the dark forest where Snelling has built his pseudoscientific palace. In case the loss is only temporary, however, I will continue to toss morsels of evidence from the lonely path.

Set your eyes to Zion, as a million generations before you

Figure 1: View south down Zion Canyon (National Park), near the base of the Emerald Pools trail. Sandstone cliff walls are comprised primarily of the Jurassic Navajo Sandstone. The Virgin River is seen cutting through the more fragile Kayenta Formation.

Easter weekend for me involved another return trip to one of the most popular hiking destinations in the American southwest: Zion National Park, Utah. Located just north of the humble valley town of Springdale, the canyon is full of visitors throughout the warm season, who include outdoor enthusiasts and office hermits alike, hailing from both faraway places like Europe and Asia and the local cities of Utah, Arizona, and Nevada. Many families make the rather convenient, ~3-hour trek to Zion National Park from the Las Vegas airport, before continuing a few hours south to the famed north rim of the Grand Canyon.

Figure 2: A tranquil valley setting, showing
the homogenous/pure mixture of sand that
comprises the sandstone cliffs of Zion.

The proximity of these parks is no coincidence. The sedimentary rock layers of Zion National Park are essentially the Early Mesozoic continuation of those found in Grand Canyon, in a long sequence of what's been termed the Grand Staircase (the uppermost layer of the Grand Canyon is Permian, the last period of the Paleozoic). This stratigraphic sequence continues into Bryce Canyon, where the later Mesozoic and early Cenozoic layers of the Colorado Plateau outcrop with astounding beauty. Now, despite the ongoing debate over exactly when and how these canyons were carved out, it is universally agreed that all three monuments to the power of erosion were formed sometime in the past 70 million years in response to substantial uplift of the Colorado Plateau.

While young-Earth creationists have commonly touted the Grand Canyon as a 'monument to catastrophe', somehow in favor of their position, this region's geology remains a testament to deep time and long, drawn-out geological processes. The 'Flood Geology' position requires a dishonest telescoping of data, fitted into an extremely oversimplified model, but a wider regional perspective as much as a detailed look at these rock formations provides ample evidence that this model is flat out wrong. I want to provide you with some basic observations, which demonstrate that the Flood Geology model fails to account for the 1) time required for deposition of sediments; 2) characteristics of the rocks prior to erosion; and 3) time required for erosion/removal of the bulk of sedimentary strata from the region.

1. Sedimentary Strata of the Colorado Plateau — all in a year's work?

Between the rim of the Grand Canyon and the peaks of Zion National Park lie more than 1,000 meters of sedimentary rock. Even if we allow the entire flood year to deposit this small fraction of the geologic column, this amounts to ~2.78 meters of sediment per day. While modern catastrophic floods have been known to deposit 2–3 meters of sediment in a single day (e.g. Thompson and Croke, 2013), the deposition is very localized (confined to flood banks) and offset by more intense erosion elsewhere in the channel. In other words, the sediment is simply moved downstream, but deposition is accompanied by distinct erosional features and does not result in flat, horizontal layers. More importantly, floods that are sufficiently powerful to deposit upward of 2–3 meters in a day are also sufficiently powerful to move large chunks of rock and debris, so that catastrophic flood deposits invariably consist of a mixture of sediment sizes, ranging from sand/mud to large boulders and gravel.

Triassic and Jurassic sediments of southern Utah are well known for their heterogeneity between layers and homogeneity within. Some layers are thin and contain only silt and clay, while others are thick, cross-bedded, and contain only medium-sized sand. Localized deposits of fine sediment or evaporites provide evidence of temporary lakes across the landscape. Shallow erosional features are common in the form of stream-sized sandstone channels, similar to modern floodplains in semi-arid regions (Martin, 2000). Perhaps the best known formation of this sequence is the red-stained Navajo Sandstone, a remnant of a massive desert dune-scape that rivaled the modern Sahara. To many a geologist, the portrait of a slowly evolving desert landscape over tens of millions of years could not be more clear.

Subtle clues to the paleoenvironment recorded by these rocks come in the form of sedimentary structures and fossils. Relatively thin sandstone beds contain planar bedding (horizontal) or epsilon cross bedding, much like modern river channels that now cross the American southwest. Massive sandstone beds of the Navajo Formation, on the other hand, are rather typical of wind-blown sand dunes, whose angle of repose (30–34°) matches that of the preserved sandstone. Experimental setups today (e.g. Fielding, 2006) have allowed geologists to distinguish clearly what kind of bedding structures (e.g. cross bedding) develop under various water depths, flow rates, etc., so that we can be confident that the Navajo Sandstone was deposited by air—not water. Other features like mudcracks or even dune collapse (e.g. Bryan et al., 2013) could not possibly form during catastrophic deposition.

Finally, fossils ranging from footprints (Lockley et al., 1998) to mammalian burrows (Riese et al., 2011) to body fossils of dinosaurs and other desert-dwelling terrestrial fauna (Rowe et al., 2010) preclude the catastrophic deposition rates required by the flood geology model, but corroborate well the conventional interpretation of these rock layers. Are we to believe that dinosaurs and small mammals were leaving footprints and making burrows while the sediment-choked flood waters raged at several meters per second? Are we further to believe that such powerful water masses imported millions of tons of sand/silt, but not an ounce of marine shells, bones, or lime mud, as is the case today when strong hurricanes/tsunamis make landfall? That is precisely what the folks at Answers in Genesis would have you believe, but this line of reasoning requires a staggering level of geological ignorance.

So the Flood Geologist is presented with a theoretical dilemma. The flood model might predict either a thick sequence of sediments, produced by a powerful slurry of sediment-choked water, or a relatively thin sequence of sediments, in which sedimentary structures and fossil features might be preserved through relatively mild, oscillating flow patterns. But they cannot have it both ways. If the entire 1,000-meter section of sediment from Grand Canyon to the Zion peaks were laid down within one year, it could not possibly contain such a diverse mixture of thin and thick, planar and cross bedded layers of sand, silt, clay, and evaporite, let alone footprints and burrows of small animals, who could never have walked amid such torrential waters. Besides, footprints and burrows in soft sediment are destroyed instantly under catastrophic flow conditions.

Along the highways of southern Utah, these massive cliffs of sedimentary rock stand testament against any rapid process of formation. So if this 1-kilometer sequence—only a fraction of the miles of sediment beneath the Colorado Plateau—cannot be explained by a year-long flood, why would Answers in Genesis go on pretending that it's even plausible for the entire geologic column (give or take) to have been laid down in a year? This is not a contrast between two worldviews examining one set of data, but a contrast between those who are willing to examine the data and those who are willing to misrepresent them unreservedly.

2. Post-flood transformation—between a soft rock and a hard place

Let us grant, for the sake of discussion, that all the Mesozoic sediments of Zion National Park were deposited within the flood year. Now how do these sediments become rocks? Under the weight of overlying sand and silt, water should begin moving of the sediments toward the surface—a process called dewatering and compaction. If accompanied by strong earthquakes, as young-Earth geologists tell us should have been the case, we would expect to find massive dewatering structures throughout the sedimentary layers.

Figure 3: Sandstone cliff exhibiting brittle
fracture zones, which somewhat resemble
conchoidal breaks in glass.

But we don't. All the layers and their bedding are intact (Fig. 3).

So how long did it take for these sediments to compact and lose enough water to begin precipitating iron-oxide cement between the sand grains (responsible for the red color of the cliffs)? By standard models of groundwater flow, this process could take thousands to millions of years, since the water is forced to flow through tiny pore spaces between grains. By no means do fresh laid sandstone bodies, hundreds of meters thick, go from sandcastle material to solid rock in a matter of days or even decades. This fact alone falsifies the young-Earth timeline, so young-Earth geologists strain at credulity in suggesting otherwise.

Flood geologists frequently make the claim that large-scale erosive processes were aided by the fact that sedimentary layers were not yet solid, meanwhile ignoring the fact that to this day, these rocks should not be solid. Even granting them this impossible scenario, however, we must note that erosion and weathering of Zion National Park exhibits features consistent only with the deformation of solid rock—not soft sediment. How old is Zion Canyon according to the young-Earth creationist? We cannot be sure exactly, and never would they offer an answer with much precision, but previous workers (like Austin and Snelling) cite retreat of the flood waters and/or residual inland seas as one mechanism to erode massive canyons in little time.

Figure 4: A side canyon, which has retreated
along a vertical fault (see right).

Figure 5: Waterfall along the main fault res-
ponsible for the side canyon. These falls are
the source of the Emerald Pools.

But if that were the case, then the erosional features of Zion Canyon make absolutely no sense. The sedimentary strata are filled with brittle fractures, joints, and faults, indicating the sediments were already solidified before the canyon eroded (Figs. 4-5). Furthermore, the canyon walls have been retreating for millennia by losing large, planar slabs of solid rock through a combination of freeze/thaw weathering and the pull of gravity. The result are pseudo-conchoidal pits on the vertical walls, as seen in the photo above (Fig. 3). Therefore, we can conclude confidently that Zion National Park was not eroded within days, centuries, or even millennia after deposition of the raw sedimentary materials. This process took far, far longer.

3. Post-flood erosion: we're gonna need a lot more dynamite...

Figure 6: Base of the uppermost Emerald Pool,
where the results of gravity and wintertime
weathering are most clearly seen. It will be
centuries before these boulders are ground
to fine sand again.

The Mesozoic strata outcropping in Zion and Bryce Canyon National Parks are not present in the Grand Canyon region, or even across much of the southern Colorado Plateau. Where did all the sediment go? We know that much of it was recycled into other formations across the western US, while the rest was carried off to the Baja region of western Mexico, where it now comprises much of the Cenozoic delta deposits of the modern Colorado River. As seen in Figure 2, rivers are extremely efficient at grinding rock slabs and boulders (see Fig. 6) down to fine sediment.

So once again, the Flood Geologist has put us into a strange dilemma regarding the Mesozoic sediments of Zion National Park. To be eroded quickly, these sediments must have been still soft, but to produce the deformational/erosional features found today, they must have been solid and well cemented. At the same time, these sediments were eroded and transported to form other fine-grained sedimentary deposits in the region, such as the sedimentary layers of the Cretaceous Interior Seaway, which extend from eastern Utah into Kansas. This could only happen rapidly if the Mesozoic sediments were still soft. But still other sedimentary deposits contain gravel and boulders of Mesozoic sandstone layers (e.g. the Iron Springs Formation of southern Utah), indicating unequivocally that the Mesozoic sediments were solid and well cemented at the time they were eroded and recycled into other sedimentary formations.

Conclusions
So which of these mutually exclusive scenarios should the young-Earth geologist choose? Were the sediments still soft or already lithified at the time that they were weathered and carried off of the Colorado Plateau? If we choose the latter scenario, we are left with one final problem: how were millions of tons of solid sand and silt stone ground to individual grains and then removed from the whole of the southern Colorado Plateau? Given the timeline offered by the Flood Geologist, it is abundantly clear that no option even begins to explain the most basic geological observations of the Zion National Park region.

I highly recommend a trip to Zion National Park, if you've not made the trip so far. It is truly a testament to deep time and the gradual evolution of landscapes in history and provides some of the most unique hikes available in the U.S. Only a few hours drive from Grand Canyon, Bryce Canyon, Red Rock Canyon, Lake Powell, Valley of Fire, San Rafael Swell (among others), one is able to trace more than ~800 million years of sedimentary strata in a single trip. Where else on Earth is that possible?

Why Aronofsky's Noah is more biblical than Ham's

Noah and son, Ham, before an ark in progress.

"Narrative creates a world...meant to be entered, inhabited, and appropriated by the reader... As the reader dwells in the created world of the story, new possibilities are opened up for articulating and conveying truth and meaning. Narrative...configures a world that has the potential power to refigure the reader's world."¹

The story of Noah and his ark is narrative, foremost. This fact alone drives a wedge between the highly artistic tale and the modern reader, who has all but lost his ability to read story. Relentless efforts by Ken Ham and company to reduce the tale to a timeline of facts—a journalistic record of the lost world—silenced the Genesis author long ago, whose profound dialogue of judgement and redemption itself drowned in a deluge of post-Enlightenment 'fact-checking'. To preserve the tale of Noah, it seemed, one should engage in cognitive dissonance and present a twisted form of geology allegedly in support of the biblical text. Any rejection of these pseudoscientific claims, therefore, meant dismissal of the biblical narrative altogether, because a false dilemma had already set firmly in the public mindset.

For this reason, I waited eagerly for years to see how Aronofsky, who could not be bothered by Ken Ham's input, would move from a few pages of ancient text to 2 1/2 hours on the big screen. His stated agenda to transform the biblical narrative into a modern warning under the blanket of environmentalism admittedly gave me pause, and I was hesitant to form any great expectations. In the wake of Ham's resurgence in public dialogue, however, I began to hope for the best. After the public debate with Bill Nye, an announcement that 'Ark Encounter' is financially afloat, and a theatrical rebuttal to Aronofsky by Ray Comfort, I wanted this to be the best portrayal of Noah ever made.

So I'm a little biased... But I did walk into the theater with inflated standards. Regardless, I wanted to see the story of Noah and his ark played out on screen, with the biblical message still intact, and that's precisely where Aronofsky delivered. In light of the evangelical uproar to censor Aronofsky, therefore, I want to tell you why I think his portrayal of Noah is, perhaps ironically, more biblical than Ken Ham's. [Note: I will avoid any blatant spoilers below, but I still recommend you see the movie first!]

1. Aronofsky's Noah lives in a narrative world

If you expect Noah to reconstruct some moment in Earth history, using only the biblical text as a script, you will be sorely disappointed. Aronofsky's Noah lives on a planet that is ostensibly 'earthy', but sufficiently unfamiliar to remove the reader from critical history telling into the mode of poetic historiography, which better captures the spirit of the biblical narrative. For example, the biblical description of Eden sounds enough like ancient Israel to inform the reader "Hey, this story is about you!", but the strange geography and inhabitants preclude any flatfooted connection to history. Such seamless blending of historical referent and imaginative symbolism is characteristic of near Eastern historiography, including that which comprises much of the Pentateuch. For this reason, I applaud Aronofsky for not giving into the literalist's plea to "just tell us what really happened!" Instead, he retells the story of Noah in a manner that speaks specifically to a modern audience, first by removing the audience from their own world and placing them into one that is familiar yet strange. This world contains its own set of rules (including a bit of 'magic'), but the moral struggles and consequences obviously apply to humanity as we know it. Aronofsky's most brilliant connection to the modern audience is made toward the end of the movie, when Noah recounts the story of creation, temptation and rebellion over a time-lapse montage of history as we know it.

2. Aronofsky's Noah is theomorphic

God is understood in the Genesis narratives less by what he says and does himself than by the characters who honor or defy him. This may sound controversial, but I assure you, the principle is demonstrated amply through character development and intertextual allusion throughout the Bible. Biblical characters are frequently named for the attributes of God they reflect biographically, echoing the statement that mankind is made in God's image. Upholding that image, Adam names the creatures of the Garden; Noah sends out a raven alongside God's 'breath' until the waters recede; Moses separates the waters from the waters to 'create' Israel from the land. Take also the story of Abraham's sacrifice of Isaac, where God's voice is hauntingly scarce, and the drama builds through a silent march to an unthinkable end. Only when Abraham has mentally committed to the loss of his firstborn does he gain his son back from the dead, so to speak. And so in the Passover plague in Egypt, God—like Abraham—regains his firstborn son, as he would again on Resurrection Sunday. God's emotional response is understood here not through mythology, but through dramatic precedent of theomorphic characters.

In Noah, God is hauntingly silent. We cannot understand who 'the creator' is or what he wants through a baritone loudspeaker in the sky, but only by the drama surrounding those who honor or reject him. Aronofsky's Noah plays out the just God, who unreservedly consigns a wicked humanity to their destruction well earned, while battling his grief over a deep love for that which is lost and hope for a new beginning. Russell Crowe (Noah) is emotionally convincing, more so than any creed simply announcing that God is both just and merciful. Perhaps the most creative example is one in which Aronofsky deviates strongly from the biblical tale, facing Noah with a murderous task involving his own daughter-in-law. This paradox is complex, and it takes a complex drama to understand fully what it means for the creator God to be the redeemer God. Speaking of which...

3. Aronofsky's Noah elucidates the grand paradox of the Flood narrative

Why did God determine to flood the land? Because of the pervasive wickedness of mankind. Why did God covenant with mankind and promise never to flood the land again? Because of the pervasive wickedness of mankind. This is the paradox played out in Genesis 6–9, which perhaps never sought to answer the question bluntly. Noah makes clear the sins of mankind, whose greed became a plague to all of creation (even its heavenly inhabitants). Most unexpected, however, is Noah's own discovery of the innate wickedness of mankind in surveying his families primal desire for self-preservation. Aronofsky improvises where scripture is silent, and confronts the audience with a Noah who learns the hard way that "mankind is evil from his youth" (Gen. 8:21).

4. Aronofsky's Noah captures the psychological torment of knowing good from evil

I anticipate much antagonism from evangelical crowds over the fact that Noah is not cast as a humble old preacher, inviting the world to his sermons while the crowds gather and cast insults. Aronofsky's Noah is rather a conflicted personality, who actively takes up divine roles, including judgement (Russell Crowe apparently retained his skills from Gladiator when it comes to mutilating oncoming barbarian legions). Lover of peace and harmony, this Noah yet discovers that he will resort to all manners of violence to protect his family and uphold divine justice. But Aronofsky provides the insight behind the personality of Noah, whose family struggles to understand him, primarily through prophetic dreams. We learn the cost of knowing good and evil through graphic display of each extreme, that in recognizing what is good and holy necessarily elucidates what is evil and repulsive. Noah is slow to learn, perhaps, and falls into drunken desperation to escape the inner dialogue, but he is comforted in the end by budding theologian Emma Watson (who plays Shem's wife). True to the intertextual overlap between Noah and Adam and Abraham, she informs Noah what it meant to make the Abrahamic choice in the new Eden. Aronofsky captures this profound message of the Genesis author far better than the average biblical literalist.

5. Aronofsky's ark accurately captures the temple imagery

In the narrative world he creates, Aronofsky need not obsess over the potentially seaworthiness of a large, wooden vessel. Instead, he lets the ark symbolize precisely what it should: a cosmic temple in which one finds the rest of God amid chaos and wilderness. It is no coincidence that according to Genesis, the dimensions of the ark are essentially a 3:1 scaling of the tabernacle—a mobile, holy structure that served the nomadic, covenant people of God. So I am thankful that Aronofsky's ark, which spends as much time in the movie on the ground as it does in the water, better depicted a temple than an 18th-century wharf. Even the barren landscape produced during the ark's construction (see image above) echoes the principle of life through death, and of new birth and innocence through sacrifice and cleansing. Aronofsky also forgoes the literalist's depiction of Noah's family as superhuman zookeepers and instead borrows from Orthodox liturgy, as Noah's wife (apparently a high-level herbalist) and sons carry incense censers throughout the stables and cause the animals to slip into hibernation. Use of symbolism over pseudoscientific zoology is a win for Aronofsky, in my opinion.

6. Aronofsky's Noah is an environmentalist

This film is hardly what I would call a propagandist piece, despite its unashamed support for environmentalism over sheer human interest. Whatever the personal convictions of the writers and director, the manner in which Noah calls its audience to care for God's creation (and that includes our fellow man) as God commanded in the beginning is perfectly in line with the biblical message. All too often, Christians are so hesitant to associate themselves with secularist or quasi-pantheistic factions under the umbrella of 'environmental responsibility' that they are willing to promote the opposite. But Aronofsky's message is so simple as to be innocent and (hopefully) effective: taking for yourself more than what you need and casting anger, hate, and violence toward your brother is contrary to God's good creation.

7. Aronofsky's Noah is conscious of the echoes from Eden

Despite the many ways in which Aronofsky takes creative license to improvise or deviate from a surface reading of Genesis, he stays true to the biblical message that a return to Eden is the essence of new creation. Several symbols are utilized throughout the movie (from the fertile seed that Noah plants, to the spring that rises from the ground and divides to water the Earth, to his patriarchal blessing to be fruitful and multiply). Thus Aronofsky's call to take responsibility for our actions equates to an exhortation to live as God commanded us from the beginning.

That this call comes now from outside the church should raise concern to us, who have been entrusted with the oracles of God and commissioned with the task of cultivating the garden of God, so that its borders cover the Earth as the waters cover the sea.


–––––––––––––––––––––––

¹ Allusion to Paul Ricoeur's Time and Narrative; citation from Diepstra, G.R., and Laughery, G.J., 2009, Interpreting Science and Scripture: Genesis 1–3: European Journal of Theology, v. 18, p. 5–16.

The Great Salt Lake: Monument to Stagnation

Reflection of the Wasatch Mountain Range (northern Utah) in the Great Salt Lake. American Bison are visible grazing near a pond at the right edge of the photo. View east from Antelope Island, just west of Farmington, Utah.

Any review of the literature by so-called "Flood Geologists" will yield a plethora of hyped-up examples, in which catastrophic geological processes supposedly occurred at warp speed in the recent past. Steve Austin's "Grand Canyon: Monument to Catastrophe" now serves as a template for reinterpreting the past to conform to an oversimplistic reading of Genesis. But closer analyses of these pseudoscientific works, which fill article databases at Answers in Genesis and Creation Ministries International, invariably reveal fundamental errors in data interpretation, and so the effort continues to battle the spread of misinformation by ostensibly evangelistic organizations.

During a recent trip to northern Utah, however, it occurred to me that these article databases are lacking a vital bit of context: the fact that for every geological example for which 'recent catastrophe' could plausibly be argued before a non-specialist audience, there exist one million examples for which catastrophic processes make absolutely no sense. The Great Salt Lake is one such candidate.

The modern Great Salt Lake, situated in the northeastern Basin and Range province of the western U.S., is but a modest residual of glacial Lake Bonneville. If you're unfamiliar with Bonneville's history, I recommend that you take an interactive tour here, courtesy of USGS. Since the peak of the last ice age, the lake's water level fell a little more than 300 meters, causing isostatic rebound of the underlying crust. As the weight of the water disappeared, in other words, the ground elevation rose several meters in response (similar to what happened in post-glacial Scandinavia to produce the fjords, but on a smaller scale).

When did all this happen?

Along the Wasatch Mountains and other elongated ranges of northwestern Utah, multiple terraces mark previous highstands in the stepwise transition from Lake Bonneville to the Great Salt Lake. The earliest dating of these shoreline sediments indicated that maximum water levels coincided with peak glacial conditions between 25,000 and 14,000 years ago (Broecker and Orr, 1958). These authors hypothesized early on that the water level tracked regional climate changes in the Great Basin, with cooler and wetter glacial conditions promoting higher lake levels.

Later radiocarbon dating confirmed and expanded upon early results (Oviatt et al., 1992), after a suite of geophysical tools were employed to reconstruct lake levels and water chemistry by comparing sections of sediment across the basin (e.g. Spencer et al., 1984). These studies revealed long periods—centuries to millennia—during which either a high-standing freshwater lake or a moderately low-standing saltwater lake prevailed.

Why should we trust the radiocarbon dating?

Putting a young-Earth spin on Lake Bonneville would involve reinterpreting radiocarbon ages to reflect the early 'post-Flood' period when atmospheric 14C was supposedly equilibrating to modern levels. In other words, the AiG and ICR crowds would consider these radiocarbon dates to be apparently old, because in their view, the lake must post-date Noah's flood. Cramming the long history of Lake Bonneville into a few hundred years, however, would result in a nonsensical portrait, in which the sediment deposition rate no longer corresponds to the inferred climate and water-level. For example, Oviatt (1997) correlated lake-level shifts to global climate changes recorded in North Atlantic sediments, the Greenland Ice Sheet cores, and numerous cave and lake records. These various geological records are all dated by different techniques, so any young-Earth twisting of radiocarbon dates immediately collapses under the weight of corroboration.

On a similar note, Cerling (1990) used the radiocarbon dates from Lake Bonneville shorelines to calibrate another dating technique, which measures the accumulation of 3He to estimate how long certain minerals have been exposed to the surface (useful for dating floods, landslides, eruptions, etc.). Success of this technique, which assumes the accuracy of shoreline dates, further corroborates the big picture of glacial Lake Bonneville.

A young-Earth spin also leaves too little time for the lake to have alternated between salt and freshwater (see below). Lake levels can change catastrophically, but rapid salinification? Not a chance. Most importantly, any young-Earth interpretation must ignore the much longer geological history beneath the salt flats and modern lake (Kowalewska and Cohen, 1998). The recent journey from Lake Bonneville to Great Salt Lake is only one at the end of an ~800,000-year string of similar transitions associated with glacial-interglacial cycles. Lakes and marshes (often saline) of various size and lifespan have covered the region since 2.1 million years ago, and the modern landscape has been in place for ~5 million years. No matter how one twists the timeline, 4,500 years is far too little to explain what represents only a thin slice at the top of the geologic column in northern Utah.

How did the lake become salty?

The Great Salt Lake is perhaps known best for its foul smell to those who frequent its shores, due to the abundance of rotting brine shrimp. These hypersaline inhabitants are the only trace of aquatic life in the lake, whose salinity far exceeds that of the ocean. In a young-Earth scenario, it might sound reasonable to posit Lake Bonneville as a remnant of the receding flood waters, but this hypothesis fails the test of chemistry. The modern salt composition is explained rather by the evaporation of river and spring water flowing into the lake (Spencer et al., 1985). When evaporation exceeds river and rainfall input, the salt content increases, because only calcium carbonate precipitates from the lake in large quantities, despite that numerous ionic compounds are carried in by rivers. In other words, the Great Salt Lake is the final product of more than 10,000 years of freshwater distillation.

Didn't Lake Bonneville drain catastrophically?

To an extent, yes. As Earth began to warm following the peak of the last ice age, a natural dam at the north end of Lake Bonneville failed. Nearly 400 cubic miles of water gushed into southern Idaho through the Snake River valley, carving numerous telltale features of megafloods into the landscape (read the full story here). As a result, Lake Bonneville fell as much as 100 meters in a geological instant.

Scablands and dry falls cut into basalt along the Snake River (image from Digital Geology of Idaho).

On the one hand, Lake Bonneville bears at least one 'monument to catastrophe', but this event puts into perspective the slow and gradual histories that bound it. The water loss during the Bonneville flood represents only half the amount lost over thousands of years of slight flux imbalance. Combine this with the fact that lakes comparable to Bonneville appeared and disappeared multiple times prior to its own existence (and without the aid of catastrophic discharges). The Bonneville flood further illustrates how catastrophic flooding affects the surface of the Earth, carving mega-ripples, pot marks, and waterfalls, to name a few geological oddities characterizing 'scablands'. These features remain 'oddities' precisely because the vast majority of Earth's surface never was subjected to catastrophic flooding.

Want to know more about the Great Salt Lake?

More than a fascinating geological site, the Great Salt Lake has both intrigued and challenged humans over a long and complicated relationship. If you want to know more about 'Our Inland Sea' from a human perspective, I highly recommend the documentary below, which packs a thoughtful arrangement of little-known, sometimes bizarre facts about the lake into 43 minutes. How did Native Americans make use of the 'sea'? The Mormons? What role did the lake play in western tourism and entertainment? You may be surprised...

Visit www.greatsaltlakedvd.com to order a copy, or view the trailer on YouTube. The semi-retro style of the documentary (and host's attire) might invoke some hesitation, but I actually enjoyed these aspects by the end. In my opinion, the video is very informative and entertaining given the modest price, and who knows, it might even inspire an upcoming visit to this natural monument.