Young-Earth Creationists on a GSA field trip: sand injectites and Flood geology

[This article is in response to a feedback question I received some time ago. The reader brought to my attention several Geological Society of America (GSA) field trips led by a group of young-Earth creationists (YECs) last year. Although young-Earth (Flood) geology was not expressly taught on the field trips, the YEC leaders visited several sites, which they believe challenge the conventional geologic timescale. I spent some time researching the claimed examples of a young Earth, and have focused here on their presentation regarding sand injectites found along the Ute Pass Fault near Manitou Springs, Colorado. Thank you again for the feedback, and I look forward to hearing more of your questions!]

Unconsolidated Earth under pressure: sand injectites in the geologic record

What is a sand injectite? In short, it is a term applied to an irregular sand body—in the form of a pipe, dike, sill, or diapir—that formed when already deposited sand was remobilized in the subsurface. Imagine standing on a sealed tube of toothpaste, and then puncturing the container with a nail, except...while the tube is buried under a layer of mud. The toothpaste, representing unconsolidated sandy sediment, is then injected upward into the overlying sediments. The resulting intrusions have been called sand injectites, sand pipes, clastic dikes, and sand diapirs, depending on their form.

Occasionally, the remnants of injectites are visible at the surface, such as in Kodachrome Basin State Park in southern Utah, or the Panoche Hills in California (Hurst et al., 2011), and outcrop examples have been known for more than 100 years. But geologists have only recently investigated the processes behind their formation. One reason is that the kinematics behind sand injection are difficult to characterize without subsurface imaging and complex physical modeling (e.g. Huuse et al., 2010; Ross et al., 2011)—tools not available to the typical field sedimentologist. Another reason is found in the following excerpt from Schlumberger, a petroleum exploration and production group, who noted:

“Under certain conditions, unconsolidated sand is remobilized and forced upward through overlying layers. Called injectites, these sands can have high porosity and permeability and play a huge role in planning and optimizing hydrocarbon recovery.”

Hurst et al. (2005) echoed these descriptors and determined that sand injectites constitute an excellent, but relatively unexplored, play in petroleum exploration, where hydrocarbon preservation potential was high. For reference, a play in the oil industry refers to a type of deposit or structure (channel sands, dune fields, submarine canyons) that could potentially trap and preserve hydrocarbons (oil and gas). Some major sand injectites, such as in the North Sea, are comprised of well sorted, homogenous, highly porous and permeable sandstones. In the oil industry, these characteristics are of prime importance when it comes to recovering the maximum amount of oil from a reservoir. Thus, sand injectites make ideal reservoir rocks, and their irregular shape aids in trapping oil and gas.

The moral of the story is simply this: petroleum exploration companies have a lot of money, and are willing to spend that money researching aspects of geology that help them better recover oil and gas. Since Dixon et al. (1995) first explored the importance of diapiric sand in petroleum systems 16 years ago, our understanding of sand injectites has grown exponentially.

Modern understanding of sand injection: triggers and fluidization mechanisms

Sand injectites begin as relatively flat (tabular) bodies of sandy sediment, such as those deposited in coastal margins or eolian dunes (e.g. Mississippi River delta and Saharan desert, respectively). During periods of rising sea level, or high subsidence, the sand is overlain by fine-grained muds, or in some cases, evaporites, which may act as a low-permeability seal during burial. Normally, water in the pore spaces of both sediment types would escape as the rock pressure increases, allowing both the mud and sand to compact—the first step of lithification. If the geometry is just right, however, the surrounding mudstone can effectively prevent pore water from escaping the sand body during burial. Not only does this cause the sand layer to become overpressured (a condition that occurs when the pore-water pressure is higher than from the weight of overlying rock alone), but it prevents cementation—the next step of lithification.

Though sandstone lithification essentially halts in the scenario above, the surrounding mud continues to undergo diagenetic modification. First, the mudstone undergoes physical compaction, in which pore water is allowed to escape. At deeper burial (6,000–9,000 ft; 100–110°C), montmorillonite (a common clay mineral) converts to illite. The process involves loss of mineral-bound water to adjacent sedimentary units (fluid migration), as well as volume loss (since illite is smaller), causing clay-rich layers to fracture at depth (Selley, 1998).

Since both modes of compaction cause the mud to shrink, they can potentially undermine the seal that had kept the sand body overpressured. Alternatively, rising hydrostatic pressure in the underlying sandstone will inevitably fracture the mudstone when the upward normal stress overcomes the strength of the cap rock. In either case, high-pressure streams of water are forced upward into the overlying sediments, along with unconsolidated sand. At this point, the extent and geometry of sand injection is only a matter of physics, obviously dependent on the parameters of each scenario (overlying lithology, burial depth, initial hydrostatic pressure, etc.).

To add some perspective, Vigorito and Hurst (2010) reported fluid pressures of ~25 MPa, or 3,625 psi, after mobilization had occurred, and estimated that 27 MPa (~4,000 psi) was necessary to cause fracturing of the mudstone seal. Compare these pressures to the average 30–35 psi in your tires! Scott et al. (2009) estimated subsurface sandstone velocities up to 9.43 m/s, or some 21 mph. Sand injection is no gradual process.

Hurst et al. (2011) summarized a number of proposed triggers for sand mobilization: seismic events, fluid migration, igneous intrusion, and even meteor impacts. These mechanisms are not mutually exclusive to a scenario involving overpressure, however, and are more likely complementary (i.e. the straw that broke the camel’s back; see Huuse et al., 2010). For example, soft-sediment deformation is common in tectonically active regions, like the Late Cretaceous Sevier Foreland Basin of southern Utah, exposed near Cedar City (Parowan Canyon) and Gunlock. If a fluid-saturated sand body is already at high pressure and unconsolidated, even a modest earthquake could set the catastrophic dewatering process into motion.

And for the record: yes, catastrophic processes are perfectly consistent with uniformitarianism!

Sand injectites are dominantly fine to medium-grained, showing graded sedimentary structures that depend on the flow characteristics (banding in lower flow regimes; absence of structure in highest flow regimes; Hurst et al., 2011). Erosion of the surrounding bedrock may also occur. Cylindrical pipes commonly contain fine-grained sand at the core, surrounded by brecciated fragments toward the edge (Hurst et al., 2011).

Young-Earth arguments based on sand injectites

Young-Earth geologists have long argued that sand injectites are problematic for the ‘uniformitarian’ timeline, because they find it inconceivable that buried sand could remain unlithified for thousands to millions of years. Rather, they will argue that sand injectites (and other examples of soft-sediment deformation) warrant a significant rescaling of the geologic timescale—in this case, from hundreds of millions of years to less than 5,000 years. But is the argument premature, given our current understanding of post-depositional sand injection? I will examine two major cases in point here, and conclude that sand injectites are not problematic for the conventional geologic timeline.

Kodachrome Basin State Park, UT

Columnar sand pipes were cited early on as evidence against the conventional geological time scale by Roth (1992), who posited that the Jurassic sandstones of Kodachrome Basin State Park should have lithified (cemented) before the supposed remobilization. He argued that sandy sediments would have to remain unlithified for some 150 million years, based on field relationships. William Hoesch of ICR restated the case here, expressing his doubt with “quotation marks” that sediments remained unconsolidated for more than even 10 million years.

Missing overburden in the Young-Earth timeline

Roth (1992) argued erroneously, however, that movement of the sand occurred as late as Pleistocene, not realizing this would require the process to take place under only a few hundred feet of overburden (i.e. very low pressure). More likely, the sand injected later in the Jurassic (~140–150 Ma; see Netoff, 2002), long before the erosional unconformity at the base of the Upper Cretaceous Dakota Sandstone was formed (~90 Ma). The injectites did not pierce Pleistocene-age sediments, but rather those sediments were deposited on top of weather-resistant quartz arenites of the columnar sand bodies.

Hoesch argued for a Cretaceous-aged injection, based on soft-sediment deformation in the Dakota Sandstone, but the two are not necessarily related. While common in Cretaceous formations in southern Utah, soft-sediment deformation (a typical sign of seismic activity) also occurs in Jurassic units (Netoff, 2002). Both records of seismic disturbance are consistent with the Mesozoic tectonic setting of southern Utah, during which time the Sevier orogenic (fold-thrust) belt was developing to the west.

Despite the uncertain timing of sand injection, it appears to have occurred at least several million years after deposition, based on the biostratigraphic constraints of overlying Jurrasic units. Deposition of the Carmel Formation, for example, is estimated at ~170–164 Ma. Sandstone injectites sourced from the Carmel Formation cut the overlying Entrada Formation, which was in place by 161 Ma. Thus a minimum of ~3 million years passed between deposition and injection. So how did the Carmel sandstones remain unconsolidated for such a period of time?

Salt: geological Tupperware

Evaporite layers, which are impermeable, cap the Carmel Formation locally and could have served as an extremely effective seal during burial. They would also prevent circulation of meteoric water to the buried sandstone. Not only would the Carmel sandstones become overpressured, but pore waters would lack the ions and oxidation state necessary for cementation to proceed. In passive margin sequences, the geothermal gradient is also typically low, so sediments must be buried more deeply than normal to reach a given temperature. Thus quartz cementation would not have occurred before the evaporite seal was broken during burial.

Geophysicist Glenn Morton has similarly commented on the arguments of Roth (1992). He correctly points out that cementation is not simply a function of age, and cites examples from personal experience where deeply buried sediments are still unconsolidated—some below well cemented strata! I will expand on his reasoning later on, with a closer look at cementation processes.

Conclusion

I do not mean to suggest that sand injectites at Kodachrome Basin are not mysterious formations—even counterintuitive on some level. These incredible statues defy tangible experience, and even challenge some very old geological dogmas. But they are not, after all facts are considered, inconsistent with the accepted timing and origin of geological strata. On the contrary, a greater challenge remains to those that believe these injectites formed during or after the Flood, while still unlithified, and yet cemented well enough in the time since the Flood to be exposed as weather-resistant landforms today.

Ute Pass Fault and associated sand dikes near Manitou Springs, CO

Every summer, the picturesque, mountain town of Manitou Springs—located just west of Colorado Springs, CO—hosts a massive tourist population. In addition to the unbeatable scenery, unique shopping experience, and local dining outlets like the Wine Cellar (my personal ‘shout-out’), nearby geological attractions such as Garden of the Gods and Cave of the Winds attract visitors from across the country—myself included (in fact, I spent part of my honeymoon there)!

The structural history of Manitou Springs region is equally enticing. Over the past ~60 million years, the Ute Pass Fault (a high-angle reverse fault) has exposed the Mesoproterozoic Pike’s Peak Granite to the south of the town. Paleozoic and Mesozoic sedimentary rocks were upwarped during the Laramide Orogeny, and are now exposed along the Front Range (e.g. Garden of the Gods). Numerous sand dikes are also found within extensional fractures of the Pike’s Peak Granite. Austin and Morris (1986) note that most dikes are found in the hanging wall of reverse faults along the Front Range, and strike parallel to Laramide faults.

Sand dikes of the Front Range in Colorado are fundamentally different from examples I cited above. Rather than piercing upward into sedimentary strata, these dikes formed when unconsolidated sand moved downward to fill extensional fractures. Nonetheless, sand dikes associated with the Ute Pass Fault are incredible examples of soft-sediment deformation (i.e. remobilization of unconsolidated sand), and are worth exploring further.

Young-Earth Creationists lead a GSA field trip to the Front Range

William Hoesch and other young-Earth geologists led a field trip at the Geological Society of America annual meeting held in Denver last year (Ross et al., 2010; abstract available here). They argued that the Cambrian Sawatch Sandstone injected into Pike’s Peak granite, which was fractured during the Laramide Orogeny and thrust on top of the Cambrian sandstone, some 430 million years after deposition. How did it turn out? One sympathetic spectator noted:

“...a bunch of PhD creationist geologists led a field trip for the premier, annual secular geology meeting. I was there on that trip...and it was like music to my ears to have 16 PhD geologists stumped.”

Austin and Morris (1986) originally advanced the argument that the timing and distribution of the sandstone dikes challenged the conventional geologic timescale. Following Kost (1984), they determined the Cambrian Sawatch Formation (~500 Ma) to be the sediment source based on similarities in textural and compositional maturity (although grains within the sand dikes were better sorted and cemented by hematite, rather than dolomite).

Most peculiar about the sand dikes is that they intrude older igneous and metamorphic rocks (Harms, 1965). Thus extensional faulting (pulling apart) of the crystalline rock was necessary for injection to take place, rather than failure of an overlying seal or cap rock. If the timing of fault formation can be constrained, however, so can the timing of sand injection.

Most injectites are found within proximity to the Ute Pass Fault, a dominantly Laramide structure, and so the timing of injection has been argued to be Cretaceous or later (less than 65 Ma) by Austin and Morris (1986). But if injection occurred as a result of Laramide movement on the Ute Pass Fault, one must explain how sandstone could remobilize after more than 430 million years of burial.

An unrealistic timeline: burial history of the Sawatch Formation

Although no geologist would suggest that lithification is simply a function of time (e.g. Selley, 1998), the proposed 430 million-year time gap of Austin and Morris (1986) would constitute a daunting challenge to the conventional age assignments. The Cambrian Sawatch Formation is not simply old, but it has since been buried by more than 2 miles of sediment. Moreover, there is no impermeable cap rock that would cause overpressuring or prevent circulation of diagenetic fluids.

Austin and Morris (1986) are correct about one thing: the Sawatch Formation could not have remained unlithified until the Laramide Orogeny, unless we are hopelessly mistaken about the age of either event. But the assertion that deposition and injection all took place during or shortly after the Flood is not the only alternative hypothesis. In fact, that scenario is falsified rather easily.

Genetic link between the Sawatch and Fountain formations

The Fountain Formation, also exposed near Manitou Springs, was deposited between the Late Pennsylvanian and Early Permian (Sweet and Sorreghan, 2010). Though dominantly sandstone, the unit is stratigraphically complex, characterized by numerous shallowing-upward cycles. Lithologies range from fine-grained mud, silt and sand to coarse, pebble conglomerates. Sweet and Sorreghan (2010) interpreted both marine and terrestrial depositional environments, and concluded that deposition took place in a fan-delta system, in which uplift to the west drove progradation of sediments toward the marine basin that covered the modern Great Plains.

Based on the geometry of the Fountain Formation, along with clast-size distribution, Sweet and Sorreghan (2010) also concluded that cyclic deposition of the Fountain Formation was driven by movement along the ancestral Ute Pass Fault, during uplift of the ancestral Rocky Mountains. While the Ute Pass Fault exposed near Manitou Springs today is a Laramide feature, the region has been tectonically active since the Cambrian (Myrow et al., 2003).

Conglomerate facies of the Fountain Formation provide further evidence for this depositional model. Sweet and Sorreghan (2010) used petrography to identify earlier Paleozoic clasts within the Fountain Formation, including weathered pebbles from the Sawatch Formation. In other words, the ancestral Ute Pass Fault, also a reverse fault, exposed older Paleozoic rocks as the Fountain Formation was being deposited to the northeast.

The occurrence of Sawatch-sourced pebbles in the Fountain Formation has significant implications for the timing of sand injection, since we may conclude that emplacement of the sand injectites occurred after the deposition of the Sawatch Formation (496 Ma), but prior to deposition of the Fountain Formation (~305 Ma). Moreover, the Sawatch Formation had to be lithified—at least on the upthrown block—before it could erode into pebbles and be deposited in conglomerates of the Fountain Formation. Sand injection did not occur during the Laramide Orogeny, because the Sawatch Formation was already lithified by the late Middle Paleozoic, more than 200 million years earlier.

Syntectonic deposits in a Flood model?

This sedimentological constraint constitutes a major challenge to Austin and Morris’ interpretation of the geologic history, since they must regard both the Sawatch and Fountain formations as Flood deposits. How did the Sawatch Formation lithify within less than a year? And if it did, then how was it injected into the Pikes Peak Granite later in the Flood, during ‘Laramide’ movement along the Ute Pass Fault? Austin and Morris thus face the same challenge they raise, and their interpretation of the sand dikes is simply not tenable in light of all geological data.

But the question still remains: when did sand injection occur? And how did it happen? Not considering the paleogeography and seismic history of the region, Austin and Morris (1986) glanced over the answer in their original paper:

 “Some workers...recognize the fundamental impossibility of keeping the Sawatch

Sandstone...unlithified and deeply buried for 430 million years until the Laramide Orogeny...These workers tend to negate the important field relationships and suggest that the dikes were actually intruded in the Cambrian while the Sawatch Sandstone was unconsolidated. Evidence of Cambrian or Ordovician tectonics of a magnitude able to open up extension fractures hundreds of feet wide, however, has not been found on the Ute Pass Fault.” (emphasis added)

Austin and Morris (1986) thus ruled out the possibility that sand injection occurred in the early Paleozoic (Cambrian/Ordovician) because 1) sand dikes are found along the Ute Pass Fault—a Cenozoic structure; and 2) they believe that only the Laramide Orogeny was powerful enough to form the wide extensional fractures now hosting the Cambrian sand. But there are a few fatal flaws in this line of reasoning.

Tectonic blunders in the arguments of Austin and Morris

Sand injection could not have taken place during the Cenozoic, because uplift of the modern Rocky Mountains was driven by contractional deformation—namely, the Laramide Orogeny. The Ute Pass Fault is a reverse fault, which forms when rocks are compressed together, but sand dikes occur within extensional faults. In the latter case, rocks are pulled apart, so the tectonic features are mutually exclusive. Austin and Morris‘ suggestion that Laramide tectonism was “of sufficient magnitude to open up the large extension fractures” is blatantly contradicted by the field evidence they had already cited. A more parsimonious conclusion is that extensional faulting occurred early in the Paleozoic (Cambrian–Ordovician), allowing for sand injection. Sand dikes were then exposed by uplift and erosion, driven by tectonic contraction, during the Cenozoic.

Austin and Morris (1986) argue that “the coincidence of the dikes along the Ute Pass Fault, a proven Laramide structure, cannot be accidental...”—and they are right. So why should sand dikes be found in proximity to and strike along Laramide faults if they were not formed at the same time? One could answer this question by a simple experiment. All you need to do is take a hammer to a brick, so that it cracks from top to bottom. Then, use a vice to squeeze the fractured brick together until the pieces break and move past each other. As you might expect, the brick will break along already formed fractures (i.e. where it is already weak).

In geological systems, this phenomenon is known as reverse-reactivation of normal faults (e.g. Kelly et al., 1999). During periods of tectonic extension, normal faults and extensional fractures form. Later, when the same rocks undergo compression, reverse faults form preferentially along older fault planes. This process not only explains the association of early Paleozoic sand dikes with Cenozoic reverse faults (namely why sand dikes run parallel to the Laramide Ute Pass Fault) and the high angle of the Ute Pass Fault (in contrast to a low-angle thrust fault), but also solves the apparent time gap of Austin and Morris (1986).

In the citation above, Austin and Morris state that “evidence of Cambrian or Ordovician tectonics...has not been found on the Ute Pass Fault.” I would argue, however, that the sand dikes are themselves evidence of Cambro-Ordovician tectonics! Although most offset on the Ute Pass Fault occurred during the Laramide Orogeny, the fault zone is primarily a Paleozoic structure that also produced thick, syntectonic deposits during the Pennsylvanian (Sweet and Soreghan, 2010) and was simply reactivated in the latest Mesozoic to early Cenozoic.

Conclusion

Austin and Morris (1986) accused earlier workers (e.g. Kost, 1984) of ignoring vital field evidence to save the old-Earth paradigm, but after closer examination, it appears Austin and Morris are guilty the same to support their own claims. In fact, Kost (1984) also used paleomagnetic data from the sand dikes to argue for an early Paleozoic sand injection, but these data were conveniently overlooked.

Overall, sand injectites near Manitou Springs are not evidence for a faulty geologic timescale, as suggested by Austin and Morris (1986). Reinterpretation of the depositional and structural history of the Front Range on a ~5,000 year timeline would create countless geological problems in an effort to solve one or two problems that do not actually exist. In fact, it does not even solve this one or two!

Appendix: Cementation of sandstone

All clastic sedimentary rocks lose both porosity and permeability with depth. Understanding this phenomenon is crucial to the oil industry, since these characteristics may determine whether or not an oil reserve is recoverable. Selley (1998) notes that 1) the geothermal gradient, and 2) the pressure regime are the primary factors controlling cementation during burial.

The sandstone layers that sourced the Kodachrome Basin sand pipes and the clastic dikes near Manitou Springs were deposited in a passive margin and intracratonic setting, respectively. In both cases, the geothermal gradient and sedimentation rate are relatively low, implying that sediments could remain unconsolidated for a very long time.

Cementation also depends on the ion composition and oxidative state of pore waters. Since silica is relatively insoluble at low temperature and neutral pH, sandstone cementation does not occur until deep burial unless ample groundwater is allowed to circulate through the sediments. In some cases, particularly near faults, oxygen-poor waters with high amounts of dissolved iron are introduced to porous sandstones that are already saturated with oxygen-rich, meteoric water. Iron is insoluble in oxidative environments, so the result is a hematite-cemented sandstone, such as in Kodachrome Basin State Park.

In other cases, carbonate-rich waters may circulate down into porous sandstone. Since acidity is lost in the process, the carbonate ions precipitate within pore spaces of the sand, forming carbonate cements. The Cambrian Sawatch Formation was cemented by dolomite, apparently sourced from the overlying Ordovician limestone/dolomite. Sand dikes along the Ute Pass Fault, however, are cemented with hematite—evidence of hydrothermal fluid interaction.

The importance of oil in cementation

If hydrocarbons migrate through unconsolidated or poorly-cemented sandstone, they may prevent further cementation, or even dissolve certain cements already in place (namely hematite). In the American southwest, white, bleached horizons in otherwise red sandstone cliffs reflect this very process. Thus the prevalence of sand injectites as hydrocarbon reservoirs is not entirely coincidental.

Early charges of hydrocarbons are sometimes responsible for exceptionally high porosity and permeability in sandstones. The Coalinga Oil Field of California, for example, yielded far more oil that its counterpart field at Kettleman Dome, because cementation was prevented by an early hydrocarbon charge in the former. If sand injectites were to lack a sufficient seal to preserve hydrocarbons, however, microbially mediated degradation of the oil could lead to rapid carbonate cementation in oil-bearing injectites as they are exhumed (Jonk et al., 2005). Thus many sand injectites and sand pipes are exposed today as weather-resistant structures.


References Cited:

Austin, S.A., and Morris, J.D., 1986, Tight Fold and Clastic Dikes as Evidence for Rapid Deposition and Deformation of Two Very Thick Stratigraphic Sequences, in Walsh, R.E., Brooks, C.L., Crowell, R.S. (editors), Proceedings of the First International Conference on Creationism, Pittsburgh, p. 3–13.

Dixon, R.J., Schofield, K., Anderton, R., Reynolds, A.D., Alexander, R.W.S., Williams, M.C., Davies, K.G., 1995, Sandstone diapirism and clastic intrusion in the Tertiary
submarine fans of the Bruce-Beryl Embayment, Quadrant 9, UKCS, in Hartley, A.J.,
Prosser, D.J. (editors), Characterisation of deep-marine clastic systems: Geological Society of London Special Publication, v. 94., p. 77–94.

Harms, J.C., 1965, Sandstone Dikes in Relation to Laramide Faults and Stress Distribution in the Southern Front Range, Colorado: Geological Society of America Bulletin, v. 76, p. 981–1002.

Hurst, A., Cartwright, J.A., Duranti, D., Huuse, M., Nelson, M., 2005, Sand injectites: an emerging global play in deep-water clastic environments: Petroleum Geology Conference Series, v. 6, p. 133–144.

Hurst, A., Scott, A., Vigorito, M., 2011, Physical characteristics of sand injectites: Earth-Science Reviews, v. 106, p. 215–246.

Huuse, M., Jackson, C.A., Van Rensbergen, P., Davies, R.J., Flemings, P.B., Dixon, R.J., 2010, Subsurface sediment remobilization and fluid flow in sedimentary basins: an overview: Basin Research, v. 22, p. 342–360.

Jonk, R., Hurst, A., Duranti, D., Parnell, J., Mazzini, A., Fallick, A.E., 2005, Origin and timing of sand injection, petroleum migration, and diagenesis in Tertiary reservoirs, south Viking Graben, North Sea: American Association of Petroleum Geologists, v. 89, p. 329–357.

Kelly, P.G., Peacock, D.C.P., Sanderson, D.J., McGurk, A.C., 1999, Selective reverse-reactivation of normal faults, and deformation around reverse-reactivated faults in the Mesozoic of the Somerset coast: Journal of Structural Geology, v. 21, p. 493–509.

Kost, L. S., 1984, Paleomagnetic and petrographic study of sandstone dikes and the Cambrian Sawatch Sandstone, east flank of the southern Front Range, Colorado: Master’s Thesis, University of Colorado, Colorado, 173 p.

Myrow, P.M., Taylor, J.F., Miller, J.F., Ethington, R.L., Ripperdan, R.L., Allen, J., 2003, Fallen arches: Dispelling myths concerning Cambrian and Ordovician paleogeography of the Rocky Mountain region: Geological Society of America Bulletin, v. 115, p. 695–713.

Netoff, D., 2002, Seismogenically induced fluidization of Jurassic erg sands, south-central Utah: Sedimentology, v. 49, p. 65–80.

Ross, J.A., Peakall, J., Keevil, G.M., 2011, An integrated model of extrusive sand injectites in cohesionless sediments: Sedimentology, v. 58.

Ross, M.R., Hoesch, W.A., Austin, S.A., Whitmore, J.H., Clarey, T.L., 2010, Garden of the Gods at Colorado Springs: Paleozoic and Mesozoic Sedimentation and Tectonics: Geological Society of America Field Guides, v. 18, p. 77–93.

Roth, A., 1992, Clastic Pipes in Dikes in Kodachrome Basin: Origins, v. 19, p. 44–48.

Scott, A., Vigorito, M., Hurst, A., 2009, The process of sand injection: internal structures and relationships with host strata (Yellowbank Creek Injectite Complex, California, U.S.A.): Journal of Sedimentary Research, v. 79, p. 568 – 583.

Selley, R.C., 1998, Elements of Petroleum Geology: Academic Press, San Diego, 470 p.

Vigorito, M., and Hurst, A., 2010, Regional sand injectite architecture as a record of pore-pressure evolution and sand redistribution in the shallow crust: insights from the Panoche Giant Injection Complex, California: Journal of the Geological Society of London, v. 167, p. 889–904.

How old is Carlsbad Cavern (Guadalupe Mountains, New Mexico)?

The Guadalupe Mountains of New Mexico and Texas are home to more than 300 caves, including those of Carlsbad Caverns National Park. If you are not familiar with the geology of the region, the National Park Service has already published a number of brochures describing the intricate, and well decorated cave system (I would recommend starting with this PDF on the development of the caves).

Many visitors and researchers alike have wanted to know, how old are these caves? In the last post, I described the most common method of dating speleothems: uranium-thorium (U-Th) disequilibrium dating. Some of the younger speleothems at Carlsbad Caverns have been dated using the U-Th method (e.g. Polyak et al., 2004; Brook et al., 2006), and cover the past 12,500 years and 164,000 years, respectively. Forty-six U-Th ages were analyzed in the latter case, and were used to model highly variable stalagmite growth (0–70 mm/kyr) and climate over the last two glacial cycles.

But this only address part of the question, because it tells us when precipitation of speleothems began, and not when the caverns were actually carved out. Unfortunately, it is much more difficult to date the removal of something in geology than its appearance (e.g. erosion of the Grand Canyon vs. the sediments being eroded).

The curious case of Carlsbad Cavern: sulfuric acid dissolution

Several researchers in the region devised a novel solution to this question (Polyak et al., 1998). As it turns out, some of the larger caves of the Guadalupe Mountains were dissolved with the help of sulfuric acid (as opposed to just carbonic acid). The unique dissolution process left its mark in the form of sulfate minerals, such as alunite, that formed residues on the cave walls, and in small cavities. Alunite is a potassium-bearing mineral, which means that it can be dated using the 40Ar/39Ar method. Since alunite forms as a byproduct of dissolution, the model age should reflect the time of cave dissolution.

Polyak et al. (1998) obtained 15 ages from the purest alunite samples (determined by XRF), representing 5 different caves in the region. Model ages ranged from 3.89–12.26 million years (precision better than 3%) and were reproducible across multiple rooms from each cave. Moreover, clay minerals from the Permian bedrock were dated by the same method, and estimated to be 278±3 Ma. Several clay-rich samples of alunite, with unusually high K/Ca ratios, yielded anomalously old ages (~30 Ma), as expected. Thus contamination could be ruled out in the primary data set by analyzing for clay content and elemental ratios (K/Ca).

40Ar/39Ar model ages, tectonic uplift of the Guadalupe Mountains, and the age of Carlsbad Cavern

Model ages from each cave were also plotted against elevation, revealing a strong correlation. This result corroborates the current understanding of cave dissolution, which is thought to occur from groundwater interaction near the water table. As the mountains were uplifted, the water table dropped, and so caves were carved out at lower and lower elevations. In other words, the oldest caves are now found at the highest elevation, and the youngest caves are found much lower.

Carlsbad Cavern, currently at ~1,100 meters above sea level, was carved out about 4 million years ago, according to alunite model ages. Speleothems would have begun long after, however, and some are still forming today.

Sulfuric acid dissolution: mechanism of rapid cave formation in a young Earth?

Back in 1998, young-Earth creationist Michael Oard tried to work the results of Polyak et al. (1998) in his favor (original article here; responding to YEC-critic Art Strahler). Mr. Oard suggested that since sulfuric acid is a much stronger acid, it could have formed caves rapidly during or after the Flood, allowing more time for speleothem formation (~4,500 years versus...4,000 years?). Currently, some 10% of the world's caves are thought to have formed by sulfuric-acid dissolution, but Mr. Oard posits that number might be larger, and the evidence has since washed away.

Greg Neyman (Answers in Creation) has already responded to the article here, showing that Mr. Oard's optimism is hardly warranted, so I will address the remaining errors here.

1) Syn-Flood vs. Post-Flood: Mr. Oard suggests that cave dissolution might have occurred during the Flood, contra his critic that deemed caves as "post-Flood" features:

"...cave formation is not necessarily a post-Flood phenomenon as Strahler thought. It could have formed anytime after the limestone was first deposited in the Flood, since hydrothermal water would be expected to begin moving through the limestone soon after deposition."

This point is hardly worth discussing, since it only moves the possible age of the cave back by one year at most. Nonetheless, I'll mention that evidence of hydrothermal fluids is common in limestone bedrock (e.g. Tritlla et al., 2001). Hydrothermal fluids typically move through fractures in the bedrock and deposit calcite veins in their path. The calcite is a mixture of dissolved bedrock and CO2 from thermally altered organic matter. Hydrothermal fluids also contain trace elements, like strontium, that are incorporated into the recrystallized calcite. Overall, hydrothermal activity is very easy to detect in carbonates, because it shifts the chemistry on every level: 87Sr/86Sr ratios drop, along with δ18O and δ13C values. Mr. Oard's hypothesis can thus be tested, but I suspect that most of his readers will rest on his 'just-so' story.

2) Biogenic sulfur: Mr. Oard contradicts himself after he confuses the origin of sulfuric acid in the Polyak et al. (1998) study.

"The sulfuric acid is formed by the oxidation of hydrogen sulfide in hydrothermal water...The 34S/32S ratio indicates the hydrogen sulfide is biogenic."

Polyak et al. (1998) mention sulfur input from hydrothermal fluids as a factor for some caves, but not in the case of Carlsbad Cavern. The significance of isotopically light sulfur is that the sulfuric acid was ultimately sourced from decaying organic matter—not H2S in hydrothermal fluids. Hill (1990), cited by Mr. Oard, linked the biogenic sulfur signal to hydrocarbons (oil) in the underlying strata. In other words, sulfur-bearing oil was oxidized in the subsurface to produce small quantities of H2S, and that H2S was oxidized to sulfuric acid (H2SO4) as it was carried through the groundwater to the site of cave dissolution.

Now, I do not highlight this mistake for the sake of trivial amendment. The fact that sulfuric acid responsible for carving out Carlsbad Cavern was a byproduct of oil degradation raises a serious challenge to Mr. Oard's young-Earth timeline, for it requires that sedimentary organic matter had already matured to oil by the time Carlsbad Cavern was forming. But outside of controlled, high-temperature and high-pressure laboratory conditions, oil does not mature overnight! At the current rock temperature beneath Carlsbad Cavern, the process would have taken many thousands to millions of years. Thus Mr. Oard's assertion that cave dissolution might have taken place during the Flood is entirely contrary to the facts.

In summary, Mr. Oard's timelines does not allow enough time 1) for oil to have matured; 2) for oil to have chemically degraded; 3) for sulfuric acid to be transported to the site of dissolution, let alone dissolve the massive caverns; 4) for the water table to drop substantially, creating a vadose zone environment; and 5) for decorative speleothems (some the size of trees!) to have precipitated.

3) Geochronological mishap: Since my focus here is on the age of Carlsbad Cavern, I will conclude with Mr. Oard's misunderstanding of the available geochronological data. Since Mr. Oard must reject all radiometric dates from cave samples—though he does not explain why, scientifically, we should—he ends the article by blankly asserting that the available data is contradictory:

"It is of further interest that the dating of alunite resulted in significantly older dates for...caves in the Guadaloupe Mountains. The new dates range from 4 to 12 million years (Ma)...Previously, the cavern was dated at 1.2–0.75 Ma, or as much as 3 Ma based on the timing of mountain uplift. The younger dates were not only based on field evidence, but also on paleomagnetic, uranium-series, and electron-spin-resonance dating...This does not give one much confidence in dating methods." (emphasis added)

If you also read my last post, then Mr. Oard's error might seem obvious. Polyak et al. (1998) did not introduce 'new dates' for the cave, as though to correct available ones. Rather, the various studies were dating entirely different events.

Paleomagnetic, U-series, and electron-spin-resonance methods are applied to speleothems or sediments within the caves. The 40Ar/39Ar ages of Polyak et al. (1998) were applied to alunite formed during cave dissolution. Obviously, speleothems and cave sediments cannot form until the cave has actually been carved out, so we would expect these dates to be younger than those for the alunite. Despite the confidence in Mr. Oard's sarcastic assessment, it remains a non sequitur.

Conclusion

The available geochronological data are thus perfectly consistent with conventional understanding of Carlsbad Cavern's geological history. Uplift of the Guadalupe Mountains began some time in the early Cenozoic. In the mid-Miocene, H2S was introduced to the groundwater, was oxidized to sulfuric acid, and began dissolving caverns near the water table. The water table dropped slowly over the rest of the Miocene, and into the Pliocene, carving out Carlsbad Cavern around 4 million years ago. Since that time, continued fall of the water table created a vadose zone within the cavern, allowing for the precipitation of speleothems (as early as 1.2 Ma or more), and that process continues today.


References Cited:
Brook, G.A., Ellwood, B.B., Railsback, L.B., Cowart, J.B., 2006, A 164 ka record of environmental change in the American Southwest from a Carlsbad Cavern speleothem: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 237, p. 483–507.

Hill, C.A., 1990, Sulfuric acid speleogenesis of Carlsbad Cavern and its relationship to hydrocarbons, Delaware Basin, New Mexico and Texas: American Association of Petroleum Geologists Bulletin, v. 74, p. 1685–1694.

Polyak, V., McIntosh, W.C., Güven, N., Provencio, P., 1998, Age and Origin of Carlsbad Cavern and Related Caves from 40Ar/39Ar of Alunite: Science, v. 279, p. 1919–1921.

Polyak, V., Rasmussen, J.B.T., Asmeron, Y., 2004, Prolonged wet period in the southwestern United States through the Younger Dryas: Geology, v. 32, p. 5–8.

Tritlla, J., Cardellach, E., Sharp, Z.D., 2001, Origin of vein hydrothermal carbonates in triassic limestones of the Espadán Ranges (Iberian Chain, E Spain): Chemical Geology, v. 172, p. 291–305.

How to put the 'paleo' in paleoclimatology: isotopic records from speleothems

Caves are perhaps the most fascinating recorders of Earth's recent climate. Though not the most popular proxy—being stuck in a world of paleoclimatology where tree rings and ice, lake, and marine cores make all of the headlines—caves have the potential to record rainfall and soil data at high resolution for thousands of years. The results are not only locked away in dark rooms, safe from the elements, but are contained within some of the most beautiful rock formations known to us: speleothems.

And that is why we take hammers to them, saw them in half, and mount them on a micro-drilling stage in the isotope geochemistry lab.

Paleoclimate records from stalagmites

By way of preface, I am slightly biased in my attitude, because I've spent the past year analyzing isotopic records from stalagmites around North America. But if you were to consider my position for a moment, I don't think you would disagree. Consider, for example, how a cave forms. Precipitation (or spring meltwater) trickles down through a carbonate aquifer, picking up metal cations (like calcium) and bicarbonate anions along the way. Steady drips of groundwater quickly lose their carbonate concentration to the cave atmosphere by CO2-degassing as they hang from the cave roof (or from stalactites). When the drip hits the floor, further degassing initiates the precipitation of aragonite or calcite (CaCO3). Give the process tens to hundreds to thousands of years, and you have a stalagmite with concentric laminae that reach toward the apex.

As it turns out, the carbon and oxygen isotopic chemistry of the laminae depends primarily on rainfall source and amount, as well as soil activity. We can test these hypotheses by comparing isotopic records from very recently formed stalagmites with human/instrumental climate records, or by comparing the isotopic chemistry of rainwater to dripwater to aragonite in stalagmites over several years. In general, oxygen isotopes are depleted in 18O (heavy oxygen) during wet periods and enriched in 18O during dry periods, but the source of precipitation also plays a role (high vs. low latitude; Atlantic vs. Pacific). Therefore, speleothem records from North America record not only rainfall amount, but migration of the Gulf Stream, El Niño cycles, and other multidecadal oscillations.

Depending on the residence time of the aquifer (i.e. how long, on average, the water takes to get from rainfall to 'cave'-fall), the groundwater will mix thoroughly with that from the past month to the past several years. This means that isotopic inputs from rainfall represent a weighted average for that time interval—good news for the paleoclimatologist. Also, most carbonate ions in groundwater are dissolved within the upper soil horizons during the wet season, so one may track soil processes as well.

Both the hydrological and geochemical processes behind speleothem formation are now very well understood. With few exceptions, stalagmites have been proven faithful proxies of climate. If the sampling process were not so destructive, I believe they would also gain some popularity.

High-resolution age dating of speleothems: answering the 'when' of cave formation

Understanding the climatic significance of isotopic ratios in stalagmites is great, but unless we know when each laminae formed, the records are quite useless. So how does one discern the 'paleo' in paleoclimate? If you've ever had the opportunity to visit a cave set up for guided tours (Cave of the Winds, Colorado and Timpanogos Cave, Utah are on my list), the tour guide likely pointed out a speleothem that had been measured over time: "You see, 50 years ago, this guy was 5 cm shorter! So stalagmites grow about 1 mm per year, and since now it's 105 cm tall, it must have been growing for...1,050 years!"

This approach is simple and intuitive, and in some cases may provide a decent approximation of stalagmite growth. But the fact is, the rate of growth for individual stalagmites can vary over time, due to fluctuations in climate. For example, high amounts of rainfall and soil activity can promote speleothem growth. Low ambient CO2 and high ambient temperature in the cave can also promote growth by increasing the rate of precipitation in each drop. Since we know all of these factors will change over the life of a speleothem, we need a more precise method of dating.

Unfortunately, the popular notion that stalagmite growth-rates are simply extrapolated, like above, has caused young-Earth critics to focus on examples of rapid stalactite growth—some rather odd—to make that case that limestone caves are compatible with a young-Earth, Flood model. But the arguments typically go like this: we know that speleothems can form rapidly under favorable conditions; therefore, all speleothems formed rapidly under favorable conditions. The informal logical fallacy is rarely challenged, because few people are familiar with actual method used to date speleothems.

Uranium-thorium (U-series) dating of speleothems

Most speleothems are originally precipitated as aragonite (calcium carbonate). But like any mineral, the aragonite is bound to contain some impurities. Magnesium, strontium, sodium, barium, and lithium are incorporated in trace amounts. As an aside, the ratio of calcium to these trace elements serves as an independent proxy of climate, occasionally used by ambitious geochemists. One of the most important trace elements, however, is uranium.

Why uranium? Because uranium is radioactive, and decays into thorium at a constant, known rate. By analyzing the current ratio of uranium and thorium isotopes, one can estimate the absolute age of laminae in speleothems. More specifically, the ratio of 234U (parent) to 230Th (daughter) is measured. But the ratio does not change like an hourglass model with time (as in the radiocarbon, K-Ar, and U-Pb systems), since the daughter product is also radioactive, and decays even faster than the parent. Let's take a closer look.

Money matters: a financial analogy

Imagine that you set up a bank account with $1,000 in savings and $0 in checking. Every month, 1% of the savings amount is transferred to checking, but 5% of the checking amount is...donated to charity. In this scenario, the money in savings represents 234-Uranium, and the money in checking represents 230-Thorium. Both accounts are constantly decaying at a constant rate, unique to each account, that depends on the residual balance. The money spent to charity represents the daughter product of thorium decay, which is neither measured in the rock nor this analogy.

At the end of the first month, zero dollars are donated to charity, because the checking account has zero dollars available. But 1%, or $10, will be transferred from savings to checking. The new balance: $990 in savings; $10 in checking. So at the end of the second month, 5% of $10, or 50 cents, will be donated to charity, and $9.90 transferred from savings to checking. The new balances: $980.10 in savings; $19.40 in checking. Easy enough?

In geology, we actually measure the ratio between the isotopes (i.e. $ in savings divided by $ in checking). If we know the rate of decay (what % is lost each month), and the original balance in at least one of the accounts, we can back calculate the time that has passed since the experiment started. Below, I have plotted the experiment over 100 months:

The yellow line represents the ratio between the two accounts. As you can see, the ratio changes very quickly at first, but eventually flattens out to equilibrium (hence the name "Uranium-Thorium Disequilibrium Dating"). This means that if one were to estimate the time passed based on the current ratio between the accounts, that estimate would be more precise at time = 0–30 months than at time = 30–100 months. Correspondingly, U-Th disequilibrium ages are most precise up to ~500,000 years, after which the change in 234U/230Th is too small to be detected.

Another limit occurs in very young samples, since the mass spectrometer is unable to detect thorium at exceedingly low concentrations. Thus ideal samples are uranium-rich to begin with, and are at least several years to several thousand years old. Personally, I have seen very precise (±1%) age estimates from U-rich samples, however, even between 0 and 100 years old.

Depending on the scientific importance of the sample, and given that each age datum costs ~$500 to analyze, between 2 and 20 U-Th dates are taken along the growth axis. This allows the paleoclimatologist to construct an age model for each speleothem, and attach real ages to isotopic records.

But aren't there a few assumptions involved?

Yes, some assumptions are made. That is how science progresses. But fortunately for us, most of those assumptions can be falsified/verified independently.

1) How do we know the initial ratio of U/Th isotopes? In oxic environments, uranium is fairly soluble and thorium is very insoluble. Since stalagmites form out of dissolved constituents of groundwater, we should expect very little, if any, thorium to be originally present (i.e. $0 in checking).

2) Does this assumption always hold? On the contrary, we expect this assumption never to hold, in the absolute sense. There will always be at least some thorium present. So to account for this, we measure the ratio of 238U to 232Th (two common isotopes). Both isotopes are radioactive, but their half-lives (4.5 and 14.05 billion years, respectively) are much longer than that of 230Th (75,380 years), and may be considered stable on shorter geologic timescales. Using the 238U/232Th ratio, the 232Th/230Th ratio, and the total concentration of uranium, we can estimate the initial concentration of 230-thorium. Typically, this value is insignificant, and will only change the age estimates by a maximum of 1% if left uncorrected. To put this in perspective, imagine that I started the experiment above with $1.50 in checking. In this case, the age estimate would be off by less than a few days.

3) How do we know whether any uranium or thorium was lost since crystallization? In speleothems, this is rarely a concern, since most ages fit very well into a growth model (i.e. they get progressively older along the axis, and result in globally correlated paleoclimate records). But if this assumption were challenged, one could use trace element data, petrography, and cathodoluminescence to test whether recrystallization of the speleothem caused a loss of soluble trace-elements. Also, any loss of uranium is likely to be localized, through microfractures in the speleothem. In this case, model ages taken from those points will show up as anomalous, and result in an unrealistic growth-rate curve. It is simply unreasonable to expect that uranium loss occurred systematically, shifting all the ages by a proportional amount.

4) How do we know the decay rates for both isotopes has remained the same? This is a matter of quantum physics, and a sound one at that. There is no reason to expect decay rates to change. If this were to happen, however, during the life of the speleothem, then the growth model would shift dramatically at a point, making it appear as though the speleothem started to grow many times faster or slower.

Are caves and speleothems consistent with the Flood model?

In short, no. The Flood model must consider modern caves and speleothems as post-Flood features. Even if one were to allow for the unrealistic scenario of accelerated nuclear decay during, the caveat would not apply to speleothems. Since thousands of speleothems have been dated beyond 5,000 years, there remains a significant challenge to young-Earth Flood geologists.

We can also consider speleothem records in the larger climatic context. For example, speleothem records match up very well with ice core records (dated by counting annual layers), marine/lake core records (dated by counting annual layers and radiocarbon methods), and tree ring records (same as above). Thus we have multiple independent methods yielding essentially the same result. Such concordance highly corroborates the use of each method to track the Earth's climate history, and thoroughly falsifies the Flood model.

A fish out of water: why did the shark cross the berm?

A fascinating fossil find

Shark teeth are some of the most spectacular remnants of life one may come across in the field. Thus, I can only imagine the surprise on Kentucky coal miner Jay Wright's face when he pulled half a jaw (teeth and all) from a coal seam back in February. The marine shark, Edestus, is estimated to have been more than 20 ft. long, making it one of the larger specimens of that genus.

The shark-bearing coal is Pennsylvanian in age (~299–318 Ma), and surrounded stratigraphically by marine shale and carbonate rocks (shallow subtidal/supratidal grainstone and boundstone). Fossils of small, marine invertebrates are apparently not uncommon in the coal, but the shark specimen represents the first, large vertebrate find.

A fish out of water?

To any keen observer, one obvious question may arise: how did the remains of a giant marine shark end up in the swampy backwoods of ancient Kentucky? Traditionally, coal is thought to have formed in densely vegetated swamps, landward of a sandy berm. Presumably, the shark did not "make a jump for it" at high tide, Free Willy style, only to find himself flopping around a freshwater mire. Thus the fossil find seems to strain at the conventional wisdom behind coal geology.

Brian Thomas at the Institute for Creation Research (ICR) took this approach in a recent article entitled "Shark Jaw Opens Questions about Coal Formation". He cites an introductory geology textbook to show that coal is thought to have formed "when millions of years of plant debris accumulated into peat bogs at the bottom of ancient swamps," and then asks, "...how did a huge shark find its way into a swamp?"

Before answering this question, we should consider Mr. Thomas's alternative explanation. Following a model by Steve Austin of ICR (whose Ph.D. dissertation focused on these very coal beds), he suggests:

"A catastrophic flood event ripped up whole ancient forests, and then transported plant and animal debris into low-lying areas. A subsequent series of tsunami-like waves then carried sediments over the top of the plant debris."

According to Mr. Thomas, this scenario could explain some geological features of the coal (absence of root casts, sharp transition to the bounding rock types, broad lateral continuity), as well as the "out of place" marine fossils.

Coal formation: the rest of the story

While potentially convincing at the surface level, Mr. Thomas's argument hardly does justice to the complex nature of sedimentary deposition, as well as the process of coal formation. Here are a few facts to consider:

1. Mr. Thomas begins by telling us the "standard textbook story is that coal seams were formed when millions of years of plant debris accumulated into peat bogs..." (emphasis mine). Unfortunately, it seems many YEC's believe that geologists fall back on "millions of years" to explain every process, and the phrase now possesses a decidedly pejorative connotation among the YEC community. With regard to peat accumulation in swamps, however, the timescale is significantly shorter (on the order of hundreds to thousands of years).

2. Coastal mires, though located on land, are not free from marine influence. If you've lived in the southeastern U.S., or simply kept up hurricane news over the past few years, then you've already seen this in action. Storms, and even tsunamis, are capable of bringing saltwater, sediment, shells, and yes, the occasional, disarticulated jaw of a large shark, onto the land. If the latter items end up in a calm, oxygen-deprived swamp, then the preservation potential is quite high. Such events are relatively rare, to be sure, but coal seams in western Kentucky contain abundant evidence of such marine influence (Eble et al., 2001). In fact, Hower and Williams (2001, p. 147) cite Dr. Austin's Ph.D. thesis (Austin, 1979), which "described marine shale partings bearing marine fossils within the coal."

3. The close association of marine rocks with coal is also due to the fact that many coals form in interdistributary bays, in addition to terrestrial swamps. In both cases, the oxygen-poor, heavily vegetated ecosystems are immediately adjacent to marine depositional environments (river delta, shoreline sands). In the rock record, adjacent depositional environments are recorded as a succession of distinct layers—a process described by Walther's Law. This is precisely what we find in the coals of western Kentucky (e.g. Dewet et al., 1991), which only comprise about 5% of the rock layers, because...

4. Coal seams form when plant matter accumulates in swamps, but in a prograding, marginal marine setting. Mr. Thomas cites an article by Stuart Nevins (found here) to suggest that the shear size (lateral extent, not thickness) of Pennsylvanian coals in this region is more consistent with catastrophic deposition. There, Mr. Nevins states that "no modern swamp has an area remotely approaching the great Pennsylvanian coals." Both authors fail to take into account, however, that coastal swamps migrate as sedimentation moves the coastline seaward during periods of low sea level. The result is a horizontally continuous layer of rock that is much larger than the depositional environment in which it was formed.

4. Coal seems thin and thicken as one traces them out laterally. They also tend to interfinger with marine lithologies (Eble et al., 2001). This phenomenon is very well explained by the process described above, but makes little sense in terms of catastrophic deposition.

5. Western Kentucky coal seams are relatively rich in sulfur (2–13 wt. %) due to fluid interaction during mire development. Seawater, for example, is very rich in sulfate, and may contribute to the high sulfur content through repeated incursion (from storms, etc.) over thousands of years. Mr. Thomas must account for the high sulfur content of these coals and, simultaneously, the low sulfur content of others.

6. Mr. Thomas states that "modern peat bogs are thoroughly penetrated by roots. Coal seams show no trace of these root masses." Eble et al. (2001) point out, however, that most coal seams are underlain by paleosols with abundant roots. Root structures are typically lost within the coal seam due to degradation of organic matter before and after burial (thermal maturation). In fact, the low oxygen content of swamps is due to the constant breakdown of organic matter, roots included.

Concluding thoughts: the culinary art of coalification

Perhaps the most important aspect of western Kentucky coal beds is the long journey from decaying plant matter to an economically useful resource. In the article cited by Mr. Thomas, Stuart Nevin erroneously rules out time as a factor in coalification. He bases his reasoning on the fact that some geologically old coals are less mature than geologically young coals. But when it comes to any petroleum product (including coal), maturation is a function of both time and temperature.

Imagine thermal maturity as a fancy term for the 'doneness' of coal. As with cooking a roast, the 'doneness' depends on the oven temperature and the cooking time. If the temperature is very low, the roast can cook for many hours, while an extremely hot oven will blacken the meat within minutes.

Mr. Nevin notes that coal can be converted from plant matter in a number of hours, given enough heat. That is true, but at what temperature have the Pennsylvanian coals of this region been since burial? Substantially lower, at less than 100–150°C. In general, reaction rates (i.e. cooking times) are cut in half for each additional 10°C. So a peat layer at 100°C will take 64 times longer to reach the same thermal maturity as a peat layer at 150°C, and more than 2,000 times longer than a peat layer at 200°C.

Thermal maturity in coal (just like in oil) is a function of both time and temperature, and thus depends on the specific burial history and tectonic setting for each region. It is not enigmatic that some geologically old coal deposits are less mature than more recent ones, since not all sedimentary rocks are buried to the same depth or exposed to the same heat source. Moreover, the current thermal maturity of coals in western Kentucky poses a serious problem for Mr. Thomas's interpretation. What takes only hours at very high (300°C+) temperatures can take thousands to millions of years at the current temperature (~100°C) of coals in the subsurface. Unless Mr. Thomas wants to propose that these coal beds were exposed to extreme heat since the flood (a testable and falsifiable hypothesis), he must admit his model does not allow for nearly enough time to explain all the facts.


References Cited:

Austin, S.A., 1979, Depositional Environment of the Kentucky No. 12 Coal Bed (Middle Pennsylvanian) of Western Kentucky, with Special Reference to the Origin of Coal Lithotypes: Ph.D. Thesis, Pennsylvania State University, 411 p.

Dewet, C.B., Moshier, S.O., Hower, J.C., Rimmer, S.M., 1991, Deposition and diagenesis of a marine-swamp margin; the providence limestone and adjacent coals, western Kentucky: Society of Economic Paleontologists and Mineralogists Core Workshop, p. 169–204.

Eble, C.F., Greb, S.F., Williams, D.A., 2001, The geology and palynology of Lower and Middle Pennsylvanian strata in the Western Kentucky Coal Field: International Journal of Coal Geology, v. 47, p. 189–206.

Hower, J.C., and Williams, D.A., 2001, Further examination of the ragged edge of the Herrin Coal Bed, Webster County, Western Kentucky Coal Field: International Journal of Coal Geology, v. 46, p. 145–155.

Radiometric Dating Recap: a response to Mike Riddle

"Δεινον δ'εστι η μη 'μπειρια..." -Αριστοφανης

Does radiometric dating prove the Earth is old? Answers in Genesis author Mike Riddle invited readers to skepticism in an article responding to this very question. Therein, he demonstrated how easily one may cast doubt on conventional interpretations of model ages from radiometric dating techniques—at least for those unfamiliar with the process and typical results. How did he accomplish this goal?

1. Assert that a "straightforward reading" is the only proper approach to Scripture, and designate any deviation from this a compromise on the veracity of God's word.

2. Offer a simplified description of how radiometric dating works in the most ideal case.

3. Remind readers of the assumptions behind "model ages" (without letting them know what a "model age" actually is).

4. Offer anecdotal evidence in which model ages are in conflict.

5. Assure readers that "conventional" explanations for the discordance have been thoroughly ruled out.

6. Conclude that the only reasonable explanation for discordance among unpublished data—which represent a tiny fraction of results from the world's geochronologists—is a past, unquantifiable change in the rate of nuclear decay in radioactive elements.

7. Divert readers from the obvious heat problem (sections 3–5; Isaac, 2007) associated with this physical model of Earth history by deeming it "a new and exciting opportunity for creation research."

I understand that Mr. Riddle's intention is to convey, in popular terms, why he does not accept published ages, and I sympathize with his desire to find concordance between God's word and creation. Having an obligation to the truth, however, I feel it necessary to comment that his approach is misleading, particularly to those inexperienced in geochronology.

1. What is a straightforward reading?

In the past 150 years, scholars have uncovered a wealth of information regarding the cultural and literary world in which the Genesis narrative was drafted. The theological implications of these findings have been debated on all sides, and such continues today. But despite the lack of consensus, it is evident that a "straightforward reading" is more elusive than originally proposed. Moreover, recent perspectives on literary criticism show that the reader's own culture and environment play an equally important role in the interpretation of ancient texts.

While I affirm the perspicuity of Scripture (its theological message can be understood properly across time and culture), I think Mike Riddle concludes prematurely that a "straightforward" reading reveals the Earth is actually thousands of years old. I have no doubt that our post-Enlightenment mentality has crept into this conclusion unnoticed, causing believers and unbelievers alike to read scientific and historical details back into the ancient text. Mr. Riddle's surface-level reading of the Genesis narrative is not sufficient reason to dismiss a priori the conventional interpretations of radiometric dates.

2. Any meaningful critique of radiometric dating must take into account the complexity behind analyses and interpretations, as well as the wide range of geological applications.


Simply put, radiometric dating is not just a method used to date igneous rocks using an hourglass model of parent/daughter isotopes. Nearly as many analyses are now performed on both metamorphic and sedimentary rocks, and the respective methods for all three systems are quite complicated (usually involving 3 or more isotopes). Mr. Riddle overlooks this point, presumably to cast doubt on the age of fossils contained within sedimentary rocks (which, he seems to believe, cannot be dated directly).

But for those interested, metamorphic histories are commonly reconstructed by dating minerals that differ in closure temperature, and/or minerals that form during metamorphism (such as garnet). Multi-domain diffusion models (constructed from 40Ar/39Ar age spectra) are used to interpret thermal histories after crystallization. Combined, these techniques offer a powerful tool to investigate mountain building processes, since they tell us when the rock was at a given temperature and pressure.

Sedimentary rocks commonly contain authigenic minerals (as well as early-stage cements like calcite) that can be dated individually. Such minerals are more susceptible to alteration than in igneous systems, but a bulk of the data are consistent with the conventional geologic timeline. This point is particularly relevant, because Mike Riddle (following the RATE team) interprets long ages of igneous bodies as a product of accelerated nuclear decay during the Flood. If decay rates after the Flood were closer to modern measurements, however, then diagenetic cements should yield very young (indistinguishable from zero) ages. Since they don't, the young-Earth model cannot currently explain the range of available data.

Detrital zircons and micas can also be dated individually to constrain the age of a sedimentary rock. Since these minerals are inherited from igneous rocks that have already crystallized, it is understood that their ages will always be older than the sedimentary rock itself. The youngest ages of detrital zircons/micas, therefore, give the maximum age for deposition. This technique may also reveal the main source of sediments. If a majority of zircons, for example, are about 55 m.y. old, then one could look for the nearest igneous/metamorphic body that dates to 55 Ma to find the primary sediment source.

3. Every radiometric date represents a model age. Nobody claims that model ages actually 'prove' the age of anything. "Model ages" are termed such because they rely on a scientific model. If the physical conditions and various assumptions within the model did not hold for a given sample, then the model age does not equal the true age of the rock. Moreover, all model ages in igneous systems represent cooling ages—not necessarily the age of crystallization. Slowly cooling or reheated rocks yield different ages for different minerals (keep in mind that isochrons constructed from several minerals assume those minerals reached their respective closure temperatures at the same time).

Finally, model ages do not prove the antiquity of rocks, because a history with uniform natural laws is already assumed within the model. So yes, model ages are contingent on the uniformity of nature and assumptions about the rock's physical history.

On the other hand...

4–5. The overwhelmingly consistent results from radiometric dating do highly corroborate the interpreted history of geological features (i.e. demonstrate that the interpreted history did in fact take place, or else the data were specifically designed to give this illusion). If this were not the case, the RATE team (referenced by Mike Riddle) would not have resorted to accelerated nuclear decay as a means to explain long ages. Instead, they would continue to cite discordant age data and geochronologists would be out of business. The fact that thousands of researchers spend millions of dollars each year to date rocks should provide sufficient reason to believe that a vast majority of radiometric dates are concordant.

Another way is to search through scientific literature oneself, or speak directly to a lab manager. I've done both, and I am happy to tell you that radiometric dating works. Within the article, however, Mike Riddle provides a number of tables with results from the RATE team. It's apparent that model ages are not always concordant (agree with each other), so what are we to make of these results?

Young Volcanic Rocks

Mr. Riddle begins by citing cases where young volcanic rocks do not yield "zero" ages. I've addressed this topic at length before, so I will only mention that the apparent problem has been known for more than 40 years. Brent Dalrymple, who invented the K-Ar dating method, discovered early on that several historical lava flows (not most, not even a majority, but some) contained sufficient radiogenic argon to give dates that were too old (~30,000–500,000 years). He predicted that the lava flows contained material inherited from older rocks (such as in fluid inclusions or microscopic xenoliths), but was unable to test this prediction. As technology improved, his hypothesis was confirmed, and young volcanics are now dated by more sophisticated methods (40Ar/39Ar, electron-spin resonance, thermoluminescence) that need not assume the rocks were originally argon-free.

But these findings have not stopped ICR researchers like Steve Austin and Andrew Snelling from spending thousands of dollars on rigged, radiometric dating games. For example, samples from Mt. St. Helens were shipped to a laboratory that openly stated their technology could not detect argon levels in rocks less than 2 million-year-old. Moreover, the only minerals that yielded ages distinguishable from zero were ferromagnesian silicates, which likely crystallized before the eruption (more info here). When historical lava flows are dated using K-Ar isochrons, 40Ar/39Ar, and other methods, the ages are indistinguishable from zero.

Isochron Dating

In the first table (Beartooth Mountains), 4 K-Ar ages are listed along 4 isochron ages. Mr. Riddle concludes that "the results show a significant scatter in the ages for the various minerals and also between the isotope methods." To say that scatter is significant, however, requires some knowledge of the statistical variance for each data set, and uncertainties are not provided here. In fact, the interpreted age from each isochron is within statistical uncertainty of the published age (2,790 Ma), so there is no demonstrable discordance.

Nonetheless, Mr. Riddle exposes his unfamiliarity with such data by noting that "in some cases, the whole rock age is greater than the age of the minerals, and for others, the reverse occurs." What does this mean? In the former case (Rb-Sr isochron), the difference is found in the population (number of samples) for each isochron age. One is built from 5 points; the other from 30. The reverse is true for K-Ar dates, because some minerals do not retain argon as well as others. It is not unexpected that the "Quartz-plagioclase" mineral yielded a younger date than either biotite or hornblende, given the lower retentivity of argon and higher susceptibility to alteration or thermal disturbance.

Recently, I took a closer look at the RATE team's treatment of isochron plots in the case of Precambrian sills from the Grand Canyon. In short, K-Ar data (including those from Austin and Snelling) are consistent with the accepted Rb-Sr isotope age of 1103 Ma. The variation in K-Ar dates listed in Mike Riddle's table (Bass Rapids Sill Sample Results) reflects the complex thermal history of the rocks, which have also been highly altered. In other words, the physical assumptions of each model age were not met. Alternative approaches demonstrate that these assumptions (no loss of daughter element; no gain of parent element) were falsified for the K-Ar method, and give a more clear and consistent estimate of the initial cooling age (of course, Mr. Riddle does not cite all the age data available).

Two other isochron methods (Pb-Pb and Sm-Nd) apparently gave slightly older dates for the Grand Canyon sills (~1.3 Ga), but there are a few suspicious features about the data from Snelling and Austin (2003; published here). First, this age is identical to that of the basement rock through which the intrusive magma flowed. Mr. Riddle cites isotopic mixing as a possible explanation for the discordance but claims that it was ruled by the authors. Such is not the case, however, and previous workers have interpreted the geochemistry of the sills to reflect incorporation of the country rock. In the case of Pb-Pb isochrons, a false isochron may be constructed from mineral samples that formed at very different times, but were part of an isotopically homogenous reservoir at one time. The false isochron age indicates the last point at which the samples were in isotopic equilibrium (in this case, about 1.3 Ga—the age of the country rock).

Secondly, the results of each isochron are statistically imprecise. In fact, the 1249 million-year Pb-Pb isochron age is actually within statistical uncertainty (±140 Ma) of the conventional age of the formation! The Sm-Nd age is beyond 2σ from the conventional, but the uncertainty (±170 Ma) is still unreasonably high. Such imprecision in the calculated isochron age is likely due to the fact that the samples were not truly cogenetic. In other words, they don't form a true isochron (this is most obvious in the Sm-Nd isochron). The major element geochemistry is variable enough between samples to suggest that significant fractional crystallization occurred. Hydrothermal circulation undoubtedly played a role in the rock's history as well. Finally, both isochrons are heavily weighted by felsic, granophyre samples from the top of the sill (which are moderately altered), so the discordance of the isochron ages is circumstantial at best.

6. Forced concordance on the RATE team's data sets causes discordance in the majority of geochronological data. Even giving Austin and Snelling the benefit of the doubt (i.e. ignoring uncertainties and problems arising from alteration), calling for accelerated nuclear decay in Earth history does nothing to solve the discordance. How so?

The reason is that a vast majority of isochron ages are, in fact, concordant. If we suppose that the decay rate of Sm was accelerated more than that of Pb, which was accelerated more than that of Rb, which was accelerated more than that of K, we can manipulate the Grand Canyon data so that they yield the same model age. But this mathematical "fix" would cause nearly every other published age to become suddenly discordant. Thus the RATE team's outrageous proposal would reduce nearly all geochronological data to absurdity for the sake of a handful of samples, but neither Mike Riddle nor the RATE team have been explicitly clear on this point.

7. We can be fairly confident that nuclear decay rates never changed. The first reason is that any major increase in radioactive decay would have left noticeable marks on the planet. Nuclear decay produces heat (the basic premise behind nuclear power plants). Faster decay would produce proportionally more heat. In the most conservative case for the RATE team, 1.1 billion years worth of decay occurred in the Grand Canyon sills during or since the Flood (let's say 5,000 years). That's a 220,000-fold increase in decay rates, on average, over the past 5,000 years, which would have produced enough heat to destroy all life on Earth (as well as the hydrosphere).

Dr. Larry Vardiman at ICR has considered this problem publicly, and rejects the conclusions of the RATE team. I understand that Mike Riddle, along with the RATE team, is confident that a solution will be found (i.e. how to dissipate enough heat to vaporize the planet, and then devise a sound reason behind the arbitrary premise). In the meantime, however, the problem should be stated more explicitly, especially to his lay readership.

Finally, Mike Riddle cites the helium diffusion study of Dr. Russell Humphreys, which I reviewed here, as the clear scientific reason for believing in accelerated nuclear decay. A close look at Dr. Humphreys' tactics shows that he not only employed bad scientific practice, but espoused unwarranted confidence in the results. Dr. Humphreys and others have never repeated the results of this decade-old experiment, but will often remind us that real science demands replication of results.

In the meantime, hundreds of other researchers have taken advantage of helium diffusion in zircon as a means to date exhumation (uplift) events in sedimentary rocks and igneous plutons. Yet not a single one yields a 6,000-year age. Ages based on helium diffusion in zircon are commonly consistent with the conventional geologic timescale, and falsify Dr. Humphreys' hypothesis thoroughly.

Conclusion


Does radiometric dating prove the Earth is old? Well, no, in a strict philosophical sense. But it does highly corroborate the conventional understanding of Earth history and the geologic timescale. Moreover, it falsifies the young-Earth interpretation of Earth history on every point. Despite their vested efforts over several decades, members of the RATE team have not been able to explain the range of geochronological data in a young-Earth paradigm. Nor have they been able to discredit the published results of geologists. Mr. Riddle's closing comment that "radiometric dating methods are highly unreliable" is not convincing to those familiar with the process and results, because it simply does not correspond to reality.

"Inexperience is a dreadful thing..." -Aristophanes

"Rock layers folded, not fractured" — or are they?

In the last of a six-part compilation of geological evidences for the Flood, Dr. Andrew Snelling argued that the absence of brittle fractures in folded strata constituted reason to believe that the sediments were laid down in rapid succession. "When solid, hard rock is bent (or folded)," he says, "it invariably fractures and breaks because it is brittle." As an example, Dr. Snelling refers to the Tapeats Sandstone and Muav Limestone of the Grand Canyon succession, which were folded into a broad-scale monocline long after they were deposited. He claims that folding in the rocks "did not cause them to fracture and break," and so the "only logical conclusion is that the 440-million-year delay between deposition and folding never happened!" In other words, folding took place shortly after they were laid down—within the last 5,000 years—but the sediments have since had time to lithify (transform into solid rock).

A challenge to 'deep time'?

The lack of faults and fractures poses a potential problem to the conventional geological understanding of sedimentary strata. If you have driven through a mountainous region, you have likely seen folding in sedimentary layers, where solid rock appears to have been bent into tight—sometimes hairpin—curves without compromising the structural integrity of the individual layers. If these layers were deposited over thousands to millions of years, then given as much or more time to harden into solid rock, and finally bent under high stress at an even later time...well, shouldn't we see some evidence for this?

Before answering this question, I should clarify part of Dr. Snelling's reasoning. If the absence of brittle fractures in folded strata is evidence that deformation took place before the sediments had time to lithify, should the presence of brittle fractures be considered evidence of a time gap between deposition and deformation? Wouldn't Dr. Snelling's argument predict that we should only find fractures in the most recent deformation events, but not in rocks that were folded during or shortly after the Flood? I'll return to this point later.

Brittle and ductile deformation—wait...what?

If these words sound foreign to you, don't shy away. Brittle deformation simply refers to processes that break a solid—cracking a block of cement with a hammer, for example—while ductile deformation occurs when the solid stays intact, but the warping cannot be reversed. Imagine a 'strong man' bending a rod of iron: the metal never cracks or fractures, but neither does it return to its original shape (like a rubberband) when the force is withdrawn. This is ductile deformation.

Rocks can undergo both brittle and ductile deformation, depending on the physical conditions. When rocks are cold (less than ~300°C) and at low pressure (within a few miles below the surface), they tend to fracture under stress—like a block of concrete. On the other hand, rocks act more like a metal bar at higher pressure and temperature, and deform plastically.

But not all rocks are the same. Most limestones and diatomites, for example, have high strengths, and are quite prone to brittle deformation. Mudstones and evaporites, on the other hand, have little to no strength, and will rarely fracture. Salt diapirs in the Gulf of Mexico and elsewhere demonstrate the ability of evaporites to deform plastically under pressure. The strength of rocks depends also on the type of cement holding the grains together (silica vs. calcite vs. hematite) and the degree of cementation. Consequently, a well cemented quartzite (silica grains and cement) can only escape brittle deformation at relatively high temperature and pressure. But low redox conditions (absence of oxygen), low water:rock ratios, and the presence of hydrocarbons can prevent sandstones from lithifying—even after deep burial—so it is possible to find ancient sandstone bodies that behave as a liquid (e.g. sand injectites).

In short, there are geological reasons to expect both modes of deformation in ancient rocks. The result depends on the specific history of each rock. How deeply was it buried? What was the burial temperature? Was the rock well cemented? What is the grain composition? These questions are useful to geologists, not only when interpreting the details of Earth history, but in determining, for example, whether fractures may have formed in a rock at depth. Fractures greatly enhance the permeability of rocks, and thus their ability to carry water, oil, and gas.

In fact, one apocryphal story tells of a woman that dreamed she would find oil on her property. Nobody would take up the challenge to drill on her property, however, because it was situated on the center of Michigan Basin—a structural basin where the oil would be expected to migrate away from the center. Eventually, the drilling effort was successful, because the rocks at the center had undergone brittle deformation as a result of broad-scale folding and the fractures trapped a significant amount of hydrocarbons.

The fact of the matter is...

Nearly all rocks exposed at the surface are thoroughly fractured or faulted, particularly those that have undergone deformation. Typically, the fractures occur at small scales, and so are only visible from up close (i.e. Dr. Snelling's photos could not possibly reveal whether brittle deformation took place). As before, the nature of brittle deformation depends on the rock properties and stresses involved, so one should not make generalizations from a single location (i.e. the Grand Canyon). Nonetheless, brittle deformation is a common process by which strain is released, so that sedimentary rock layers may continue to bend into all kinds of folds while preserving the bedding structure.

In addition to fracturing, however, many rocks can accomodate strain by slow recrystallization. In limestones, calcite components can dissolve under pressure (with the aid of water) and recrystallize at points of lower stress. The result is thousands of microcrystalline veins that run like fibers through the rock (styolites), which are only visible in hand sample or under the microscope. Sandstones and other clastic rocks can also deform slowly, through a similar method of recrystallization. As long as water can migrate through the rocks, it is entirely possible for rocks to bend into hairpin folds without a significant amount of fracturing.

The conventional explanation?

Dr. Snelling mentions another process in passing, and says the "conventional explanation is that under the pressure and heat of burial, the hardened sandstone and limestone layers were bent so slowly they behaved as though they were plastic and thus did not break." Of course, the citation comes from a textbook on structural geology, rather than a specific treatment of his Grand Canyon example. But he continues: "...pressure and heat would have caused detectable changes in the minerals of these rocks, tell-tale signs of metamorphism. But such metamorphic minerals or recrystallization due to such plastic behavior is not observed in these rocks."

Both the Tapeats Sandstone and Muav Limestone were deeply buried at one time (~2 miles of sediment accumulated on top of these sediments in the Grand Staircase region), but nobody would suggest that low-grade metamorphism took place (burial at these depths corresponds to ~120°C). Thus Dr. Snelling's claim that evidence is lacking constitutes a rebuttal to a question that does not exist. Nonetheless, it is fair to ask whether Dr. Snelling has even demonstrated that these rock layers were folded without undergoing brittle deformation. If there is evidence for such, it would be visible in hand sample or thin section (under the microscope), but neither are provided for us.

Until then (or until I am able to visit these rocks myself), I can at least point out that the Muav Limestone comprises a major aquifer in the western Grand Canyon area and hosts several springs. The rock's permeability is primarily due to faulting and connected brittle fractures (secondary porosity). Perhaps Dr. Snelling did not look close enough?

Dr. Snelling's argument works against him

Regardless of the nature of rock layers in the Grand Canyon, there are abundant example of brittle deformation in rocks elsewhere. A Google image search for "anticlinal tension fracture" will get you started without having to leave home. But next time you do find yourself hiking or driving past folded sedimentary strata, take a close look. Most rocks will contain abundant evidence for brittle deformation as a result of folding or uplift—and now you know what to look for!

I have also provided a couple pictures at the bottom of this post. These rocks represent the equivalent of the Tapeats Sandstone and Muav Limestone in northern Utah (Ogden Canyon), where the rocks have also been folded on a broad scale (during propagation of the Sevier Fold-Thrust Belt). In the picture on the left, the brittle Tintic Quartzite (silica grains and cement) has fractured throughout and even shattered in some points. On the right, anticlinal tension fractures are visible in the Maxfield Limestone (see Dr. Snelling's cartoon of how these form).

Now I will return to the question I originally asked: if the absence of brittle fractures in folded strata is evidence that deformation took place before the sediments had time to lithify, should the presence of brittle fractures be considered evidence of a time gap between deposition and deformation? I would answer yes. These sorts of fractures do not occur in unconsolidated sediment, so the rocks must have been well cemented at the time of deformation. In the Utah example, deformation must have occurred prior to the development of Lake Bonneville (the glacial-maximum equivalent of the Great Salt Lake). When was this, according to Dr. Snelling?

In an effort to provide evidence of deposition in rapid succession during the Flood (and deformation immediately thereafter), Dr. Snelling cites one of the most powerful arguments against his interpretation of geologic history. According to Dr. Snelling's view of the Flood, we should not expect to find abundant evidence of brittle deformation in these rocks, but in fact we find it everywhere. Brittle faults and fractures are testament, rather, to the deep time behind geologic processes others have come to appreciate.



Brittle deformation in Cambrian strata from Ogden Canyon, northern Utah

Tintic Quartzite, Ogden Canyon, UT

Anticlinal tension fractures in the Maxfield
Limestone, Ogden Canyon, UT

A Kingdom-oriented approach to Christian unity: balancing obedience to the Word and compassion for the man

Last week, I commented on the dispute between Ken Ham and Great Homeschool Conventions, concluding that one should not simply dismiss their opponents' words, whether through ignorance or censorship, if one wishes to remain relevant to the public discussion. I argued that Ken Ham's criticism of Dr. Enns and Biologos constituted an act of censorship (though unintentional on the part of Mr. Ham, I believe) in that he publicly attacked the respective party's integrity and commitment to God's word as authoritative, rather than dealing with the specific arguments put forth by each. I termed this kind of response 'censorship' because it effectually silences the words of others by preemptively undermining their credibility.

I am open to the possibility that I have missed where Ken Ham has dealt with Dr. Enns' arguments, or the specific challenges raised by Biologos, with regard to biblical exegesis and how to define inerrancy. Admittedly, I am not familiar with Ken Ham's books (at least those published in recent years), and I trust that he addresses the topics at length there. My impression from his blog posts and audio clips, however, is that he commonly avoids the tough questions when possible, or provides only a superficial response. Again, I would be happy to be proven wrong on this point, but even then I would still encourage Mr. Ham to employ less rhetoric for the sake of dialogue that is edifying to all.

On a related note, one commentator here has pointed out that Mr. and Mrs. Dean responded to Ken Ham by 'censoring' him from the convention, and so my accusation is one-sided. That is true, in one sense, and I'm glad the point was raised. Thus I need to qualify my accusation: Mr. and Mrs. Deans' response ("act of censorship") was qualitatively different in that they were not arguing against Mr. Ham's position. They wanted Ham's message to be heard, and invited other speakers to present it in his place. The action was disciplinary, not polemic.

Christian unity and fellowship amid disputes

Whether or not you agree with my assessment of the situation, I have recalled it here to raise a more important question: how should Christians approach others in the church with whom we disagree? And does our method of resolution depend on the point of disagreement? If we disagree, for example, on whether to allow musical instruments during worship, do we seek reconciliation one way, and if we disagree on the deity of Christ, do we take a wholly different approach?

Ultimately, this question is too broad for a blog post, so I merely want to make a few observations. First, consider the two examples above. I think the majority Christian response would be: "The choice to use (or not) musical instruments depends on the congregation, or might be a pastoral question; but on the deity of Christ, there is no room for discussion and compromise—any disagreement on this critical issue warrants excommunication (treating one as outside of Christian orthodoxy and/or outside of the church)."

On the one hand, we have issues that seem trivial to most observers (from within and without). What kind of songs can/should be sung in worship? Which translation of the Bible should we use? Can art can be hung in a place of worship? On the other hand are more fundamental, sharply defined doctrines, which have classically defined the Christian faith: the deity and messiahship of Christ, trinitarian monotheism, baptism and eucharist, the resurrection, justification by grace through faith. The former set of questions are typically resolved by the local eldership/pastor, while the latter are defined (e.g. Nicene Creed, Westminster Confession) and upheld (consider the recent reaction to Rob Bell) on larger, ecumenical scales.

Somewhere in the middle are topics debated quite frequently amid interdenominational exchange: the mode of baptism, covenant status of children, eschatological hope (or non-hope) for the church, role of law in Christian piety, election and the scope of the atonement, and—should I say?—creation. Many Christians effectively reach across these doctrinal boundaries (e.g. Desiring God Ministries), but the prevalence and openness of debate has the potential to wear on the human spirit and cause tension, if only intermittently.

So far, this structuring to Christian disputes may seem obvious, or even too simplistic. Well, I am guilty on both accounts. But let me move on to my second observation. All of the issues mentioned above have been used by Christian congregations, at one point or another, to break fellowship with others. Not simply to form a new congregation or denomination, but to sever dialogue and cast out. What some deem trivial quibble (or part of Christian cultural tradition, not to be bound to the conscience), others may view as a means to bring schism and condemnation.

At the same time, there is great danger in blind ecumenism. If our goal in promoting Christian unity is God's promise through his covenant, then theology matters, and though it may cause tension among us, we cannot treat the pain with apathy. For the church to survive itself, our attempts at reconciliation in doctrinal disputes must embody a healthy balance between obedience to the Word, and compassion for the man.

Easier said than done? Well, yes, but it has been done—if only once.

A kingdom-oriented approach to reconciliation

The canonical gospels, while rich in story and teachings, were not primarily written to provide an historical account, or even to establish a uniquely Christian belief system. Each gospel recapitulates the story of Israel using early 1st century events to establish that Christ is the climax to the Jewish narrative, and that through Christ, God has inaugurated his kingdom on Earth. Paul summarizes the act in saying "[God] rescued us from the domain of darkness, and transferred us to the kingdom of His beloved Son" (Col. 1:13). As the "image of the invisible God, the firstborn of all creation" (Col. 1:15), Christ represents that to which Adam and, by proxy, ourselves were called, but have failed. Elsewhere, Paul expands on this point through an early Christian hymn:

"Have this attitude in yourselves which was also in Christ Jesus, who, although He existed in the form of God, did not regard equality with God a thing to be grasped, but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men. Being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, even death on a cross." (Phil. 2:5–8)

Unlike Adam in the Genesis narrative, Christ did not "grasp" (as toward the fruit) at his "equality with God" (echoing the serpent's promise to Adam; Gen. 3:4). Moreover, he remained obedient to the Word (his own divine nature and the Father's will) unto a death that was intended to reconcile God's creation to himself—slaves to the Master; sinners to the Holy One.

Theology in practice

What makes the gospels so vital to the life of the church is that they reveal to us not only what Jesus said and did, but who he was and how he felt. Jesus loved his own (John 13:1), even when they were blind to the obvious truth. Through compassion, he revealed the will of God to those that just didn't get it (Mark 10:21). Whether in breaking cultural boundaries (John 4:1–26), or following the road to cavalry, Jesus' compassion for man was such that he faced humiliation on every possible level. He forfeited reputation and reward for the sake of reconciling others to God. But he also wept at the face of death (John 11:35), elucidating the fragility of the human heart. Finally, he succumbed to frustrations with the outright mockery of God's temple (Matt. 21:12), revealing an uncompromising commitment to God's commandments and glory. All in all, the gospels provide a 'kingdom-oriented approach' to Christian unity through the character and person of Jesus.

We will, inevitably, fall short of this expectation when actually dealing with others in the church (or outside). Our interaction is complicated by the fact that each of us is not only fallible, but actually inclined toward reinforcing our own pride and reputation. The poetic words of Alexander Pushkin are very appropriate here: "The illusion that exalts us is dearer to us than ten thousand truths." Unfortunately, it is not always obvious when we lie to ourselves to protect our vested interests. John Calvin's sentiment regarding the first commandment was nearly identical, when he said "the human heart is a perpetual factory of idols."

To compensate for our intellectual frailty and proclivity to idolatry, we cannot afford to shut out the words of others, even when we think the truth is obvious. Accused dissidents of Christian orthodoxy should not "be marked out and avoided," as one blogger put it. Out of respect for the truth, and the hope of God's kingdom, we must face the issue head on—both academically, in open dialogue, and privately, through prayer—as Jesus did toward the Pharisees and as Paul did toward Peter and the Galatians.

When we approach others in theological dispute, we must be willing to place the spiritual well-being of our 'opponent' above our own reputation. This means that in calling others to orthodoxy, we should be eager to call ourselves to the same. Moreover, if our call to orthodoxy is not driven by compassion for the Word and the man alike, then we risk the danger of lapsing into Pharisaism. We may possess a great light, but in keeping it to ourselves, we become dead inside (Matt. 23:27). To put it crudely, we are like a 6-year-old who just told his entire first-grade class that Santa is not real—we may be right, but to what end?

Controversy over creation

There are many Christians who purport that belief in a 6-day creation should make or break fellowship. To them, it falls in that set of fundamental doctrines, on which there can be no compromise. Others, like Ken Ham, are passionate about this doctrine and warn others not to compromise, but are at least willing to openly discuss their reasons behind doing so. I was surprised by Mr. Ham's comments about Dr. Enns, partly because he has long been committed to open dialogue. I hope that despite recent events, he may remain committed to such.

Overall, I am more grateful now for others that are willing to engage in discussion—not simply to make their case but for the sake of truth and the hope of the kingdom. Despite my lengthy criticism of Roger Patterson's published work, I sincerely believe he maintains a healthy balance between obedience to the Word and compassion for others, and so I welcome his comments here. On a similar note, I am encouraged by posts like this one from Dr. Jay Wile (and again here). There, he demonstrates how we can still learn from those with whom we disagree.

Beginning and ending with Christ for the sake of the church

I will end my discussion anecdotally. Last week, I was listening to N.T. Wright's presentations at the Wheaton Theology Conference from last year. In his discussion on Paul, Dr. Wright lamented that in modern Pauline scholarship, very little is said about Paul's theology of the church. Whether or not you agree with Wright's view on Paul, this stinging point must be dealt with: Paul writes much about justification, election, the cross, etc., but his letters are everywhere saturated with the church and Christian unity. Even where he addresses justification at length (e.g. Romans, Galatians), it is done in the context of Christian unity.

Now I understand better a bit of pastoral advice I once heard: "Unless we are constantly reforming our ecclesiology, the rest is for naught." On that note, I hope you will consider my thoughts on resolving divisive controversies within the church (or how my abstract picture can better be put into practice). I am eager to hear your feedback, as well, for this post is hardly meant to be assertive and overbearing.