Exploring the wonders of geology in response to young-Earth claims...

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Sunday, February 20, 2011

Review of Chapter 6 – The Geologic Column, from 'Evolution Exposed: Earth Science'

Since I have already commented at length on the nature of the geologic column—how it was constructed, correlated, and dated—I will try not to repeat myself here. I am interested, rather, in defending a number of geological concepts that were criticized by Mr. Roger Patterson in Chapter 6 of his book Evolution Exposed: Earth Science, which was recently published online by Answers in Genesis. Therein, Mr. Patterson also offers a young-Earth alternative to geological concepts found in popular Earth Science textbooks. By way of preface, I sympathize with Mr. Patterson’s passion for improving standards in education and his eagerness to encourage critical thinking in the classroom. In my own high school biology classroom, I raised challenges to the teacher with regard to Earth history, common descent, and the geologic column. Though I have since answered those questions myself, it was this sort of critical discussion (albeit uncomfortable for most teachers) that inspired me to further pursue studies in the natural sciences. Nonetheless, I believe critical thinking can be encouraged without promoting a false dilemma between ‘young-Earth Christianity’ and ‘old-Earth Secularism’. Moreover, a healthy discussion is only stifled by the use of bad arguments on either side, and I believe that in an effort to undermine traditional Earth-science textbooks, Mr. Patterson cites a number of invalid arguments from various other young-Earth authors.

“Brute facts are mute facts”: interpreting the geologic column

Before delving into the geological details, Mr. Patterson reminds his readers that the facts “must be interpreted”, and he is right. Since geology is most commonly a hermeneutic science—interpreting historical data from natural (as opposed to artificial) experiments—geologists are well aware of the importance of starting assumptions. Of course, geologists are still human, and many modern debates (such as the nature/existence of mantle plumes) are at times driven by a geologist’s personal desire to corroborate his/her model of how things work. While bias can prolong a debate or the lifespan of a failed paradigm, however, it cannot survive in the research community if contradictory evidence mounts or another model better explains the data. When Mr. Patterson likens the debate between young-Earth creationists and “evolutionists” to a difference in starting assumptions, he not only oversimplifies the discussion (young-Earth advocates have not addressed a majority of the data), but misrepresents the nature of scientific evidence. “Billions of years” is not a starting assumption by anyone in the sense that geologic evidence is interpreted to support it (neither is an initial molten Earth, for that matter). Rather, it is the concluding interpretation of geologists assuming the validity and constancy of physical laws.

Before moving on, I would point out that Mr. Patterson overlooks the relevance of another hermeneutical science: biblical exegesis. He insists that when geologists try to reconstruct Earth history, the “real difference comes down to interpreting the evidence based on man’s understanding of billions of years, or using the Word of God as a starting point.” In essence, his pairing of “billions of years” and “Word of God” on mutually exclusive terms works to convince the reader that the debate is about philosophical authority alone. But the idea that the author(s) of Genesis 1–11 described a sudden appearance of Earth several thousand years ago is an interpretation of the textual data, and is contingent on a number of assumptions that play into the exegesis of the passage. One could reverse Mr. Patterson’s dichotomy by phrasing it this way:

The real difference comes down to interpreting the evidence through an understanding that God’s power and divinity are revealed in His creation (Rom. 1:20)—whose vastness, antiquity, and natural order reflect its Maker—or limiting the message of Genesis through lexical absolutism, demanding that science concord to man’s cloudy understanding of scripture, and derogating the wise providence of God by arbitrarily invoking miracles in history to explain contrary data.

By associating an old-Earth approach with a God-honoring hermeneutic—and the young-Earth approach with man’s cloudy judgment—one can induce favor from the target audience without having to demonstrate his/her position. Granted, Mr. Patterson’s focus in this chapter is not exegetical, but his choice of wording is potentially misleading to the otherwise inquisitive reader.

Uniformitarianism, and measuring geologic rates in the past

Young-Earth creationists commonly misunderstand the concept of uniformitarianism, and strive to present it as antithetical to their own interpretation of Earth history. In short, uniformitarianism is the two-fold, guiding principle in geology that: 1) physical laws have remained constant throughout time; and 2) past geologic events should be interpreted in light of known, modern processes when possible. Until recently, most young-Earth researchers have upheld (1), and I would argue that all geologists (“Flood geologists” included) would uphold (2) in principle. Although most young-Earth advocates claim adamant opposition to uniformitarianism (Mr. Patterson terms it an “unverifiable assumption”), they regularly employ it within their own research (e.g. sedimentary structures, sorting of fossils, erosional features, etc., all of which are interpreted through modern processes by adjusting variables like water depth/velocity). The confusion is a result, I believe, of their general disdain for Charles Lyell—whose contributions to geology resulted in a mainstream shift away from Noahic interpretations of sedimentary strata—but without discernment that Lyell’s Steady-State Earth hypotheses do not constitute uniformitarianism.

Failure to understand the definition and application of uniformitarianism can result in misguided accusations against conventional geological research. Mr. Patterson claims, for example, that “there is no absolute way to measure rates at which past events happened,” but the statement is demonstrably false, or at least demands an unrealistic criteria for scientific investigation. Consider two natural processes: tree growth and stalagmite formation. By studying the environmental factors that affect the pattern of tree rings, dendrochronologists have developed effective methods to interpret growth rates of individual trees—methods that can account for anomalies like forest fires, etc. that suspend or augment growth. Radiocarbon dating of individual tree rings provides an independent check on the interpreted ages. Consequently, scientists can use these data to measure growth of individual trees, forests as a whole, or even rates of sedimentation and mass wasting in the surrounding soil (e.g. soil creep on a hillside). In a cave system, slow dripping water precipitates carbonate and sulfate minerals to form magnificent structures (called speleothems). Paleoclimatologists are particularly interested in this process, because individual laminae of stalagmites record the chemistry of the water at the time of mineral precipitation (and hence information about the climate).

But how do we know how rapidly the stalagmite grew?

We must answer this question to assign a meaningful date to each lamina in the rock. From Mr. Patterson’s comments (he calls uniformitarianism “the doctrine that present-day processes acting at similar rates as observed today account for the change...in the geologic record”), you might think the rate is simply assumed to be similar to modern, observed values. In other words, one would measure the current rate of growth and just extrapolate back in time. But the rate of growth is different for each stalagmite, and can vary substantially within a single stalagmite, depending on the climate history. Therefore, paleoclimatologists use the Uranium-Thorium (U-Th) method to date laminae along the growth axis, and interpolate the values between points. [Theoretically, one could date every lamina, but at ~$500 per date, such would be fiscally irresponsible!] Like the radiocarbon method, U-Th is most accurate for young samples (less than 10,000 years old), but is reliable to ~500,000 years in many cases. Furthermore, it can be checked against historical (eyewitness) accounts of climate events in the region.

So in one sense, Mr. Patterson has a point: we cannot go back in time and directly measure rates of geological processes. On the other hand, we can apply the scientific method to interpolate (not extrapolate) the rate of processes in Earth history. I emphasize the scientific method here, because our interpretations can be falsified or verified through independent means. So what is the difference between the examples above and the approach of young-Earth researchers? Mr. Patterson will later explain that a significant portion of the geologic column was laid down within a year during the Flood, and dividing ‘how much’ by ‘how long’ gives you a rate. He applies a categorical distinction because in his eyes, God is the eyewitness of Earth history and has revealed certain events in scripture. The distinction is unwarranted, however, because according to the same scriptures, “The heavens declare the glory of God; the skies proclaim the work of His hands. Day after day they pour forth speech; night after night they reveal knowledge...they use no words...yet their voice goes out into all the Earth...” (Psa. 19:1-4) and “since the creation of the world God's invisible qualities...have been clearly seen from what has been made...” (Rom. 1:20). In other words, our witness to past geological events (and, consequently, the providential acts of God) is also written in the rocks, and disagreement between the two should cause us to reconsider our fallible interpretation of both.

Nicholas Steno and the principles of stratigraphy

Whether or not you are a geologist, I would recommend the story of Nicholas Steno’s contributions to science. First, Steno reasoned that fossils are the remnants of past life forms, based on the similarity of fossilized shark teeth to those of modern sharks. His conclusion was met by an important problem, however—namely, that one must account for how a solid (fossil) can appear inside of another solid (rock). Steno solved the dilemma by proposing that certain rocks could be formed over time as particles (mud, sand, and fossils) settled out of a water column (i.e. sedimentary processes). He employed this interpretation of sedimentary rocks to develop a set of principles for interpreting the relative history of rocks in contact with one another and geologists use those principles to this day.

When Nicholas Steno published his principles of stratigraphy in the early 17th century, he argued that fossil-bearing rocks may have been the result of Noah’s flood, inline with the available knowledge about Earth history. But consider Mr. Patterson’s description of Steno’s work:

“[Nicholas Steno] actually based his reasoning on the biblical account of the Flood and accepted that the earth was only about 6,000 years old—a Bible-believing creationist laid the foundation for modern geology!”

Steno may be rightfully credited with laying some important foundations for modern geology, but the statement above is somewhat misleading. First, Steno actually applied the yet-undefined principle of uniformitarianism to reach his conclusions about geological processes. He did so by interpreting the rocks in light of known, modern processes, and assuming the constancy of natural laws. The biological origin of fossils and ‘Principle of Superposition’ are not the necessary logical conclusions from the Flood story, and so many naturalists in the early church did not hold the same opinion about fossils and geological strata. While Steno’s acceptance of the Flood story as a global account caused him to interpret rocks in light of that event, we should not misinterpret the process he utilized. Later geologists, including Christians, used Steno’s principles to demonstrate that the Flood could not have been a global event. Their disagreement was not a matter of starting assumptions, but the result of having more data available. In short, Steno contributed much to science by remaining faithful to both witnesses to nature and following the evidence.

From index fossils to millions of years

I have described elsewhere the use of index fossils and radiometric dating methods to construct the geologic column, so I only wish to comment on a few of Mr. Patterson’s thoughts. Keep in mind that index fossils are those that are found 1) across a wide geographic area, 2) are easily distinguishable from similar species by their physical morphology, and 3) have a relatively short life span within the geologic record. In other words, index fossils are named as such for their ability to assign rocks to specific time periods in Earth history. Despite the considerable success of geologists in using index fossils to guide their research (from stratigraphy to paleoceanography to petroleum exploration), Mr. Patterson argues against their viability for a number of reasons.

“Slight differences in shell shape or structure are used to assign the shell to a new species, despite the variation apparent within a single living species today.”

In the fossil record, organisms can be distinguished only by their physical characteristics, in contrast to the modern setting, where species are differentiated on biochemical, genetic, and other factors. Paleontologists recognize this, and typically use the term morphospecies to describe a unique fossil form. A morphospecies is not intended to be the taxonomic equivalent to modern biological species, hence it matters not whether the observed variation might have occurred within a single species.

“Another problem with index fossils is that, rather than being proof of evolution, evolution is already assumed to have occurred.”

In fact, the use of index fossils has almost nothing to do with evolution. One must only assume that fossil assemblages from the rocks of interest are representative of life at the time of deposition. Whether those life forms got there by evolutionary diversification, divine creation, or by alien transplant makes no difference in practice. Index fossils are not used, therefore, as proof of evolution. On the other hand, the pattern and occurrence of index fossils does corroborate macroevolutionary theory (i.e. evolutionary theory predicts diversification into empty niches after extinction events, inline with what is observed in the fossil record).

“The idea that life became increasingly complex over time...was used to analyze the fossils in the rock layers. It was assumed that by identifying the order of fossil succession, the layers could be correlated from one region to the next. Index fossils are still one of the major indicators of the age of a given layer.”

Unfortunately, the line of reasoning within this paragraph is backwards, as it should read: the ability of geologists to correlate the order of fossils from one section of rock to the next gave way to the idea that life became increasingly complex over time; thus index fossils became one of the major indicators of the relative age for a given rock sequence.

Early on, geologists attempted to calculate the absolute age of sedimentary rocks through a variety of extrapolations, but the advent of radiometric dating surpassed all previous attempts both in accuracy and elegance. By the time any radiometric dates were assigned, geologists had already determined the relative age of rocks and assigned boundaries to geologic periods based on the fossils. In the past 70 years, paleomagnetism, astronomical cycling methods, and chemostratigraphy have provided independent checks on both relative and absolute ages (see here for further discussion).

“If the ages determined for a fossil do not fit the presuppositions, the ages are often massaged until they fit within evolutionary thinking.”

All Mr. Patterson has described here is the fact that radiometric dating is not a perfect process, and a valid interpretation must fit the overall picture. In other words, anomalous data cannot be used to overthrow the entire paradigm (this is true in all academic disciplines). In the case that a radiometric date contradicts the expectations from other geological data (e.g. fossils), the scientist should reconsider his/her interpretation of both, and repeat the experiment. Imagine that one day you bought a new bathroom scale, took it home and weighed yourself, only to find that you are suddenly 50 pounds lighter than expected (or estimated from your height and stature). What do you do? To start, you could formulate multiple competing hypotheses and design an experiment: either a) you lost a significant amount of weight without noticing, or b) the scale is broken or badly calibrated. Of course, the simplest way to resolve the matter is by attempting to falsify (b), in which you could weigh yourself on several other scales. This is not a case of “massaging” the data, but of using the scientific method to ascertain the truth and resolve apparent contradiction.

As an aside, if Mr. Patterson wants to properly challenge the interpretations of radiometric dating, he must propose or cite an alternative understanding that can be tested scientifically. Whether or not one accepts the underlying assumptions of biostratigraphy, the fact that it accurately predicts the results of radiometric dating must be reconciled with any competing model.

The Grand Canyon

Many people find it peculiar that young-Earth creationists so commonly use the Grand Canyon to explain Flood geology. I would suggest the reason is that the Grand Canyon is one of the simplest places to understand the geologic column in general, and perhaps the only place to understand the geologic column from a young-Earth perspective. The ‘Great Unconformity’ at the base of the Grand Canyon is presented as evidence for the onset of the Flood, while thick bodies of overlying sediments are arranged in a rather simple, ‘pancake-layer stratigraphy’ that is said to represent repeated transgression of the Flood waters over the continent. Despite numerous problems with this model, the presentation is very effective to those not familiar with the details of Grand Canyon geology. At the same time, anyone familiar with the geological complexity of strata outside of the Colorado Plateau will recognize that this interpretation cannot be applied to a majority of locations on Earth, and so young-Earth publications rarely speak about the geology of...well, anywhere but the Grand Canyon.

To cite a few brief examples, I want you to consider these cross-sections from western Wyoming, Virginia, Nevada, and Spitsbergen. Each link corresponds to a geologic cross-section from that region that is available online, so you can follow along.

The cross-section from Wyoming illustrates what is called a ‘fold-thrust belt’, which resulted from several mountain-building events that compressed the crust and sedimentary rocks until they were thrust on top of one another. For those of you in northern Utah, you can see a similar cross section firsthand by driving through Ogden Canyon. As you can see from the image, many of the faults (solid, near-vertical lines) are cut off by other faults, which means that sediments had to be laid down and turned into rock before the next faulting event occurred (see the bottom of the image between the words “Darby Thurst” and “Absaroka Thrust” for one example). If the sediments were unconsolidated (still soft) during faulting, or saturated with water, then they would have acted as a liquid and the faults and fold structures would not be preserved today. The structural complexity of the region provides sound evidence that a great amount of time was required to produce the local stratigraphic arrangement. Not shown on the regional cross-section (the scale is too large) are numerous ‘syntectonic’ deposits. These rock formations are conglomerates that formed during mountain-building, and contain weathered fragments of the older sediments, including limestone, mudstone, and quartzite boulders. Once again, if all of these sediments were laid down within a year (or even within several thousand years), then the underlying sediments would have been too soft to form the gravel and boulders (especially quartzite) now found in syntectonic deposits.

The cross-section from western Virginia shows a similar arrangement of folded sediments accompanied by faulting. One difference is the near vertical orientation of rock layers seen on the right side (near Richmond). Now the question is, how long does it take, not only to turn such massive layers of rock on their side, but to erode a majority of the rock, leaving behind the landscape now seen near Richmond? Mr. Patterson and others might be tempted to say that receding Flood waters could do the job in no time, but no evidence of rapid erosion (such as large canyons, or scablands) exists on the eastern plain. Instead, the region is characterized by gentle hills and mature river systems.

This image shows only the Mississippian to Permian-aged rocks in the Great Basin, so I would only point out a couple of details. First, the Ely and Pequop limestone groups transition into shale units to the west. This lithologic pattern is similar to what is found in a modern continental shelf to slope environment (consider the eastern coast of Mexico as one moves toward the Gulf). Moreover, the fossils, sedimentary structures, and chemistry of the rocks are consistent with such an environment. Secondly, note the shape of the Great Blue Formation. The reason it is thicker than adjacent units is that it contains a reef/sandbar geometry, where sedimentation was higher than toward the coast or basin. Again, the fossils, sedimentary structures, and chemistry are consistent with this interpretation. None of these rocks show evidence of rapid deposition, but each contains remnants of a past, healthy, marine ecosystem like those seen today. So the most parsimonious interpretation is that these rocks were deposited over long periods of time when the see covered much of the western United States.

In this image, you can see a transition from shallow-water, coastal sediments (left) to deep-water, continental slope deposits (right). The ancient, submarine topography is evident from the shape of the unconformities (bold lines). Fossils (oysters), sedimentary structures (cross-bedding, lamination, etc.), and lithologies (rock types) are consistent with the modern setting and show no evidence of rapid deposition beyond the occasional storm deposit or turbidity flow. Furthermore, ancient channels (note the features labeled ‘tidal inlet’) are preserved in the layers, and suggest that long periods of time were available to erode the submarine landscape before the sea transgressed.

Grand Canyon Formations — evidence of global catastrophe?

Mr. Patterson reflects the sentiments of other young-Earth researchers in his description of the rocks found at Grand Canyon:

“The layers exposed in the walls of Grand Canyon and in the Colorado Plateau region provide evidence of a catastrophe that must have covered at least the entire North American continent. The layer known as the Navajo Sandstone contains minerals that were eroded from the Appalachian Mountains. A river is used to explain this in the uniformitarian model, but a global Flood makes more sense of the evidence. The Tapeats Sandstone contains large boulders and was deposited in storm conditions over an immense area of north America. The Redwall Limestone extends from the Southwest to Pennsylvania and Tennessee—obviously deposited as the result of a massive catastrophe.”

I understand that the scope of Mr. Patterson’s book does not permit him to detail his reasoning as to how the “global Flood makes more sense of the evidence”, but the few points above warrant some discussion. First, it is not surprising, under the “uniformitarian” model, to find minerals in a desert dune deposit from long distances. One of the characteristics of the Navajo Sandstone is that the sand is very well sorted—this indicates the grains had time during transportation to homogenize. Prevailing winds over a continent (such as in northern Africa today) accomplish this task efficiently. Rivers can do the same. Consider, for example, the Arkansas River, which carries sediment from the Rocky Mountains to the Gulf of Mexico (via the Mississippi). Second, boulders in the Tapeats Sandstone are derived from the underlying Precambrian rocks. This suggests that Precambrian sediments were buried and lithified before they were eroded and deposited within the Tapeats, again consistent with the “uniformitarian” model. Finally, the geographical extent of the Redwall Limestone is not necessarily indicative of a “massive catastrophe”. In fact, it is simply impossible to deposit such quantities of carbonate rock over a large region without significant incorporation of sand, mud, and clay material.

Paleogeographers use the magnetic signature of rocks to infer the latitude at time of deposition. Along with clues from the sedimentology (fossils, structures, etc.), they can create ‘paleomaps’ of the continents at a given time. Click here to see a reconstruction of North America during the Mississippian (340 m.y. ago), when the Redwall Limestone was being deposited. Sea level was higher, and the continents were lower, so the ocean covered much of the continent. This image represents the combined work of hundreds of geologists that study Mississippian rocks, and provides an interpretation that explains all relevant data—from the type of rocks deposited, to the fossils they contain, to the chemistry they record, to the radiometric dates of minerals contained within the rock. There is simply no reason to believe the Redwall Limestone was deposited amid a global catastrophe.

Concluding remarks

In an effort to spark critical discussion of conventional geologic topics presented in school textbooks, Mr. Patterson raises a number of ‘plausible-sounding’ objections from young-Earth researchers. When examined in detail, however, the objections find little support in the geosciences. In fact, Mr. Patterson’s main counterexample—the Grand Canyon—only substantiates the concepts found in those textbooks.

In line with many Flood geologists, Mr. Patterson does not accurately describe the process by which the geologic column was constructed. Moreover, he misinterprets the concept of ‘uniformitarianism’ and overlooks the fact that even young-Earth geologists apply this principle in their own research. Consequently, I think it is inaccurate to refer to the “uniformitarian” model over against young-Earth claims.

Although I sympathize with Mr. Patterson’s passion for education, and agree that more critical thinking is needed in the classroom, I sincerely believe that the young-Earth presentation of the geologic column is not rooted in scientific observation and may stifle much-needed inquiry from students regarding the evidence that actually exists. For the sake of accountability on both sides of the discussion, I hope that I have responded fairly to his claims and that he might consider my criticism as amiable confrontation out of love for the truth.


  1. Well, I guess it all boils down to the difference in how we view Scripture. I see a global flood (one that covered the entire surface of the spherical earth, just to be clear) in Genesis and understand it to have happened about 4,300 years ago based on the biblical genealogies. Because I start from those ideas, my understanding of the evidence is different from yours. We can never agree on the nature and explanation of the geologic record based on those differences. You'll have to change my mind about the nature of the Flood before you can get me to accept your understanding of the evidence. It's not about changing my mind as to the interpretation of the evidence; it's about the truth from God's Word that must be the starting point for looking at the evidence.
    The nature of the gospel is at stake in this discussion, not just our understanding of a pile of rocks. This is clear from Peter's connection of Noah and Christ. 1 Peter 3:18-20 and 2 Peter 2:4-11 and 3:1-18 attest to Peter's understanding of the global nature of the Flood and it's connection to Christ.

  2. Chiming in late...

    There's no doubt that there was a flood, just not a global flood, the idea of which would have been unfathomable to people who didn't understand that the earth wasn't just the ground under our feet but an oblong spheroid spinning on an axis rotating around a star that they saw as the light the ruled the day, etc. Righteous Noah and his family survived thanks to God's call on his life and Noah's obedience while other's in the ANE—the known world—perished in judgment. The point of the events (not just story, but events) is that God is doing what He has always been doing; He wants to relate to us but our sin, our unrighteousness, offends His holiness. His judgment comes but a righteous remnant is saved.

    It does not surprise or bother me at all that God accommodates Peter's limited understanding of the physical world because his understanding of spiritual realities is right on.

    You know, at times I think some people think if the Bible was written today, the creation account being recorded for the very first time, we'd get it right. We wouldn't! There's still so much about the way this wonderful universe works that we can barely fathom. (Think super strings and seven additional dimensions.) God tells us what we can't figure out for ourselves. That's what revelation is.

    Roger, I doubt you think the earth DOESN'T spin on an axis and orbit the sun. But at one point in history, denying that would have been the belief "based on Scripture." Yet science has shown us how it really works and we can let go of that flawed understanding of Psalm 104:5 and embrace what the Psalmist is trying to say about the dependable character of God.

    Anyway, peace brother.