In a recently published article entitled Fossilized Footprints—A Dinosaur Dilemma, Dr. Andrew Snelling of Answers in Genesis examines a particular set of prints, located only a few kilometers from Jerusalem, Israel, in the village of Beit Zait. The dinosaur footprints referred to by Dr. Snelling (see also the photographs from his article) were first reported by Avnimelech (1962; 1966), who described them as theropod tracks from the Middle Cenomanian (about 96-98 million years ago), possibly belonging to the genus Elaphrosaurus. This was the first fossil evidence of dinosaurs, in fact, for the Middle East region. The ~20-meter path included left and right-foot imprints, in which three toes (20-26 cm in length) were clearly visible. Based on the size of the prints, and distance between them (80 cm), the creature was estimated to be about 2 meters tall and 2.5 meters long.
Dr. Snelling argues that although preserved footprints provide an apparent challenge to Flood geology, namely that dinosaurs could not have left such prints in the course of a global catastrophe, the evidence from this case is not only consistent with the Flood model but contradicts conventional geological interpretations. In this article, I will look more closely at the conventional interpretation regarding these footprints and the rocks in which they are found, in order to analyze the strength of his challenge. Before I do this, however, let’s take a look at his argument.
A proposed dilemma
Dr. Snelling begins by noting challenges on both sides of the argument: “with the Flood waters covering the entire earth, the dinosaurs would have nowhere to walk. Even if they did, the churning waters would erode away any footprints left behind...on the other hand...if geologic change takes place slowly, surely footprints made in mud would be obliterated by wind and rain long before the prints were covered by new sediments and hardened into rock.” We’ll explore these challenges later.
It is not Dr. Snelling’s intention, however, to argue the mechanics behind the preservation of footprints. The bulk of his argument is geared toward the nature of this particular case, since the tracks were formed in dolomite. He asserts that dolomite is formed either locally in extreme environments (not suitable to dinosaurs) or regionally in hypersaline marine or lacustrine settings (like the Persian Gulf or the Dead Sea; also not suitable to dinosaurs). Thus it should surprise us to find dinosaur prints in such a peculiar rock.
Unless, of course, we allow for the possibility that chemically unique marine sediments were deposited catastrophically in waves during the Flood. In this scenario, dinosaurs (and other creatures) would be threatened for their lives, and these tracks would rather reflect their attempted escape route during intermittent calm periods. Lime sediments would be carried in from distal marine settings, and then exposed when the water receded between depositional events. Catastrophic plate tectonics are cited as the mechanism controlling these tsunami-like events, whereby it would be expected that volcanism also played a major part in the process. In fact, Cretaceous sediments in Israel are interbedded with volcanic tuff layers and localized lava flows (Segev et al., 2002; Segev, 2009) not mentioned by Dr. Snelling. The importance of volcanism, he says, is that it would elevate temperatures and add magnesium to the carbonate-saturated waters, producing large quantities of dolomite.
At first, the argument seems plausible. If the sedimentology suggests a marine environment but fossil evidence suggests otherwise, there is a direct contradiction in the conventional understanding. Furthermore, he offers a mechanism by which dolomite was laid down, and the model seems to explain the relevant data. Unfortunately, proposing a ‘plausible’ hypothesis is only the first step of scientific investigation, and there are easy ways to test the underlying assumptions here.
Back to the basics: What exactly is dolomite? And how does this relate to dinosaurs?
In case you’re not already familiar with the geologic terms, let’s take a closer look. Carbonate rocks in general (limestone, dolostone) are rocks primarily composed of minerals containing the carbonate ion (CO3). In pure calcite or aragonite, the carbonate ion is bonded to calcium (CaCO3), while in pure dolomite, the carbonate ion is bonded to an equal mixture of calcium and magnesium ([Ca,Mg]CO3). Dolomite does not precipitate under normal marine conditions (i.e. normal temperature and salinity), however, so marine sediments are typically composed of calcium carbonate (CaCO3), which is the main constituent of limestone.
Initially, this seems to present a problem. Thick sequences (sometimes miles thick) of carbonate rocks are present throughout the world, comprised of both limestone and dolostone. But if dolomite does not form in normal ocean conditions, where do thick dolomite bodies come from?
It is true that dolomite forms in some ‘extreme’ environments, such as hypersaline lagoons and lakes. It is not hypothesized that large dolomite bodies formed in “oceans with unusual chemistry”, as Dr. Snelling proposes, but rather that restricted circulation to the open ocean (such as in the Persian Gulf) can raise the salinity or concentration of magnesium (both of which promote dolomite formation). Most dolomite is diagenetic, meaning that it was originally limestone that was later modified chemically during burial. This can occur through the interaction of fresh and marine water, or the mobilization of cations (like Mg2+) from clay minerals in adjacent layers (Brigaud et al., 2009). Two other important processes are hydrothermal alteration from deep, hot fluids brought up through faults and fissures (e.g. Tritlla et al., 2001; Sha et al., 2010), and microbial mediation of cations (e.g. Sadooni et al., 2010). In the former, dolomitization is localized, cuts across stratigraphic boundaries, and leaves the rocks chemically distinct with regard to stable isotopes. Thus it is very easy to identify hydrothermal dolomites in field and laboratory analyses. In the case of microbial mediation, bacteria living in anoxic pore spaces of sediments produce excess magnesium during the reduction of sulfate (i.e. magnesium is a waste product during metabolism by certain bacteria). This process can account for regionally dolomitized sediments without invoking “unusual chemistry” in the oceans, and is particularly effective in intertidal (the zone between low and high tide) and supratidal (above high tide) environments (Sadooni et al., 2010).
A minor detour. At this point, you may have the impression that limestone is a rock simply composed of calcite crystals, while dolostone is a rock composed of dolomite crystals. Limestone can be broken down into dozens of categories, however, based on the abundance, type, and origin of grains and mud. Grains can include anything from shells, microfauna (tiny shells), carbonate sand (like on a Bahaman beach), pieces of previous limestone rock, algal-bound or fecal-bound spheroids (called pisoids and peloids), coral, or even strands of calcareous algae. Calcium carbonate mud tends to fill in the gaps, but other minerals can be present as well: sulfates, clays, quartz, and more. Sedimentary and biogenic structures are common in limestone, and include cross-bedding, mudcracks, and microbial matting (in planar laminae or as in stromatolites), to name a few. Taken together, these characteristics give abundant information about the environment and energy of deposition — how deep the water was, how fast it was moving, and its chemistry. Thus by walking up a hillside composed of limestone layers, you can retrace the history of changing environmental conditions as the sediments were being deposited.
If you’ve already become bored at the thought of interpreting carbonate rocks, then I would like to reassure you that you are not alone. Many geologists share a general disdain for carbonates: they’re confusing and tend to tear holes in your clothes during field sessions. At the same time, the complexity of carbonate rocks allows us to better understand numerous variables at play. So pressing on, let’s consider the relationship of dolostone to dinosaur tracks.
Stratigraphic dolomites in the rock record: case of the carbonate platform in Israel
The tracks reported by Avnimelech (1962; 1966) are located in the Soreq Formation (Sass and Bein, 1982), which is part of the Cretaceous Judea Group. While the Judea Group consists largely of thick limestone and dolomite layers, the specific kind of limestone and dolomite varies geographically. In other words, if you trace the layer of dolomite containing dinosaur fossils to the northwest, you will find it transitions to fine-grained limestone and dolostone typical of a lagoon (in the central Israel region), then into coarse-grained limestone containing abundant rudist corals (in the Carmel region), then back into fine-grained limestone with broken shell and coral fragments (shelf break) and finally into shale (continental slope) (Buchbinder et al., 2000; Bachmann and Hirsch, 2006). In other words, there is a logical order to the interpreted environments, which represent deposition on a carbonate platform (Sass and Bein, 1982). A similar transition could be seen if you started on a beach in northeastern Australia and travelled northeast across the Great Barrier Reef.
Dr. Snelling’s assertion that the lateral extent of limestone and dolostone implies that the “Judea Group was probably formed in a vast ocean sitting over the entire region” is somewhat misleading. His oversimplification overlooks the fact that a majority of carbonate rocks in Israel formed in very shallow water, and that many were frequently exposed to the air (particularly those rocks near modern Jerusalem). Thus it is premature to rule out the possibility that dinosaurs (or any other terrestrial creature) could be living in the area and leave footprints. A geographical reconstruction of the region, using interpreted depositional environments, suggests that during the Cretaceous period, much of western Israel was covered by shallow seawater that was semi-restricted from the open ocean by rudist coral reefs to the west. The shoreline ran north-south, approximately between Galilee and Jerusalem, but migrated to the east and west many times in the Cretaceous (Buchbinder et al., 2000). Sass and Katz (1982) explored the origin of dolomites comprising the Soreq Formation, and tested various models using geochemical data. Their findings suggest that the dinosaur-bearing dolomite is of diagenetic origin, in which Mg replaced Ca and Sr in existing calcite sediments during burial. They also ruled out the possibility that it was formed during intense evaporation in an arid environment (i.e. the modern Dead Sea or Arabian shore), undermining Dr. Snelling’s claim that “the best explanation [conventional geologists] can suggest is that, for some reason, a dinosaur walked across an intertidal mudflat in an arid region (where there was nothing for him to eat!).” On the contrary, numerous dinosaur fossils are found in coastal settings. I’ve personally recovered many (theropod teeth in particular) from Bryce Canyon National Park, which also records this time period along the Cretaceous Interior Seaway. Finally, there is no reason to believe that dinosaurs would be confined to humid, tropical settings. Modern reptiles are quite often the most successful fauna in the driest climates. However, clay mineralogical analyses by Gertsch et al. (2010) suggest alternating humid and semi-arid conditions in the Mediterranean region during the Cenomanian, precluding the notion of a hermit theropod.
Gratuitous assertions vs. tested hypotheses: a tale of two models
I mentioned earlier that Dr. Snelling’s proposed model seemed plausible at first, since it contained a consistent explanation of relevant data, but that the model was easy to test. The reason is that much of the data needed is already available in previously published studies. Here is my assessment.
Sedimentology
In Flood geology, catastrophic plate tectonics would provide the mechanism for sediment transport and deposition over Israel. In other words, massive earthquakes and shifting plates would drive tsunami-like currents over the continents. However, these carbonate rocks are not a disorderly mixture of lime mud, shells, and more, but form cyclic sequences that reflect drastically different depositional environments (Sass and Bein, 1982). For example, some layers contain bedding consistent with nearshore wave activity, while others contain no bedding (quiet water) or even mudcracks. Lenses of shale, chert, phosphorite, anhydrite, and quartz geodes can be found, which only form in calm waters or periods of high evaporation. This is simply contrary to what one might expect during a global catastrophe, but perfectly consistent with a model of slow deposition in a carbonate platform. Of course, one could propose that this simply reflects repeated transgression over the continent during the flood, in which case we may consider the stratigraphy.
Stratigraphy and Paleogeography
If these rocks were laid down as sediments were repeatedly washed over the continent, what would be the expected geographic distribution of lithofacies (i.e. types of limestone/dolostone)? In this model, there is no reason to expect only fine-grained shale and carbonates in the outer shelf (interbedded with chalk), coarse-grained carbonates and large-scale coral reefs in the middle shelf, and fine-grained carbonates and dolomite in the inner shelf. One would rather expect a smooth transition from coarse to fine, fine to coarse, corresponding to the energy of waves. The distribution of Cretaceous limestone and dolostone can be logically interpreted in the context of slow deposition along a shallow carbonate shelf (Sass and Bein, 1982; Lipson-Benitah et al., 1997; Buchbinder et al., 2000), but simply makes no sense in terms of catastrophic deposition.
Even assuming the possibility that the Flood model can explain the distribution of sediments here, one may still consider the sheer thickness of units. Segev (2009) reports a thickness of ~1,800 meters for Cretaceous and younger carbonate rocks in Israel. Note this does not include the vast thickness of rocks underlying these units, but still requires an average of ~5 meters per day deposition in a year-long flood (or a more reasonable estimate of 10 meters per day during the advance of the flood). At these sedimentation rates, it is simply not possible to form the many sedimentary and biogenic structures (small-scale cross bedding, evaporite lenses, microbial stabilization of thin laminae) seen throughout the section.
Biostratigraphy and geochronology
Though I wish to save the details of fossil correlation to another article, it is worth pointing out that carbonate rocks in this region can be correlated over long distances by species of microfauna — namely, foraminifera and calcareous algae. These fossils are extremely small, only visible under a microscope, and their ordered succession can not be explained by hydrodynamic sorting, potential to escape danger, or original environment (these organisms simply float around in the surface ocean). How is it, then, that the same order of species can be found in southern Israel that can be found in northern Israel (Lipson-Benitah et al., 1997) that can be found in Morocco (Gertsch et al., 2010)? Again, this is consistent with conventional models of slow deposition over a carbonate platform, but can not be explained by rapid, catastrophic deposition.
Consider also that layers of volcanic tuff are present throughout carbonate sequences in Israel. These volcanic rocks have been dated using K-Ar and 40Ar/39Ar methods (Segev et al., 2002; Segev, 2009), yielding internally consistent and concordant ages between 140 and 82 million years (the expected range, based solely on biostratigraphy). This means that the results are reproducible and that ages become progressively younger toward the top. Regardless of whether you accept these ages, it is difficult to explain why stratigraphic layers correlated on species of microfauna also yield similar radiometric ages, outside of the conventional model. But wait, there is more!
Chemostratigraphy and ocean chemistry
The ratio of stable isotopes from elements like carbon, oxygen and strontium in carbonate rocks can be used as proxies for seawater chemistry at the time of deposition (e.g. Saltzman et al., 1998). Thus significant changes in these ratios over time are interpreted to represent major oceanographic events in Earth history (e.g. Kump and Arthur, 1999). One such event occured in the Cenomanian, associated with the Oceanic Anoxic Event 2 (Ando et al., 2009), and is recorded in carbonate rocks from the Mediterranean region (Gertsch et al., 2010). Why is this important? Stratigraphic layers of carbonate rocks that are correlated based on index fossils and radiometric dates also contain similar trends in carbon and strontium-isotope ratios. How does one explain this phenomenon in the Flood model? Isotopic ratios should reflect the sediment source (i.e. the chemistry of the ocean during deposition of the original sediments) or the process of diagenesis (chemical alteration after burial), but overall trends are independent of lithology (rock type) and degree of diagenesis (e.g. limestone vs. dolostone). In other words, there is no reason to expect a positive spike in carbon isotopes to be present in one kind of limestone from northern Israel, dolostone from central Israel, another kind of limestone from Morocco, and limestone from the bottom of the Pacific Ocean, unless we interpret their deposition in the conventional framework: these rocks were deposited slowly in their respective depositional environments, and the isotope ratios reflect seawater chemistry at that time. On the contrary, the Flood model would predict a relatively homogenous distribution, or a strong correlation to rock type (reflecting the sediment source).
On a final note, Dr. Snelling proposes that magnesium and hot water added from submarine volcanism during the flood may have promoted the deposition of dolomite. However, we have already seen that dolomites in this region are geographically confined to the most inland part of the section (i.e. furthest from submarine volcanism). Furthermore, although some lava flows and volcanic tuffs are interbedded with dolomite, others are surrounded by calcite-rich limestone and chalk (Segev, 2009). A final test would lie in a stable-isotope analysis of the dolomites. If the formation of dolomite was driven by hot, volcanically derived fluids, we should expect carbon and oxygen isotope ratios to be very low (Tritlla et al., 2001; Brigaud et al., 2009; Young et al., 2009; Sha et al., 2010), strontium concentrations to be relatively high, and 87Sr/86Sr ratios to be significantly lower (reflecting a mantle source, as opposed to continental one; e.g. Aldo et al., 2009). However, none of these factors characterize dolomites from the Soreq Formation (Sass and Katz, 1982) or other dolomites of the region (Stein et al., 2002). Isotope ratios in carbon, oxygen, and strontium are consistent with marine limestones from this period, and show no sign of influence from hydrothermal or volcanic fluids. In fact, the only deviations are found in altered dolomite lenses containing higher strontium isotope ratios, which reflects a terrestrial water source (in this case, a lagoon during the Pliocene; Stein et al., 2002).
Conclusion
Dr. Snelling raises several valid challenges to the preservation of dinosaur footprints in dolomite and the conventional interpretation of these rocks. At the same time, he tries to offer an internally consistent model that seems to explain these data in light of Flood geology. However, a closer examination of his model reveals that numerous impossibilities and contradictions undermine the initial plausibility and consistency perceived by his readers. Though I understand the article is aimed toward a general audience, I suspect that Dr. Snelling himself is not entirely familiar with the complexity of issues regarding the interpretation of carbonate rocks. A brief and limited review of existing scientific literature also revealed that many of the issues raised in his article have been thoroughly addressed (in far more detail, in fact, than I’ve been able to convey here). Furthermore, Dr. Snelling seems unaware of, or unwilling to engage in, the range of stratigraphic and geochemical methods used to test the hypotheses produced by his model. Existing data was available and sufficient to test the current Flood model, which was falsified on every account. The same data are consistent with the hypothesis that sediments from the Soreq Formation (Judea Group) were deposited across a shallow carbonate platform that covered much of Israel during the Cenomanian stage (Cretaceous period). Thus a significant challenge remains to Flood geologists to account for these footprints, as well as the rocks in which they were found.
References Cited:
Ando, A., Nakano, T., Kaiho, K., Kobayasha, T., Kokado, E., Khim, B., 2009, Onset of seawater 87Sr/86Sr excursion prior to Cenomanian-Turonian Oceanic Anoxic Event 2? New Late Cretaceous strontium isotope curve from the central Pacific Ocean: Journal of Foraminiferal Research, v. 39, p. 322-334.
Avinemelech, M., 1962, Dinosaur tracks in the lower Cenomanian of Jerusalem: Nature, v. 196, p. 264.
Avnimelech, M.A, 1966, Dinosaur tracks in the Judean Hills: Proceedings of the Israel Academy of Science and Humanities, Section of Sciences, v. 8, 19 p.
Bachmann, M., and Hirsch, F., 2006, Lower Cretaceous carbonate platform of the eastern Levant (Galilee and the Golan Heights): stratigraphy and second-order sea-level change: Cretaceous Research, v. 27, p. 487-512.
Brigaud, B., Durlet, C., Deconinck, J., Vincent, B., Thierry, J., Trouiller, A., 2009, The origin and timing of multiphase cementation in carbonates: Impact of regional scale geodynamic events on the Middle Jurassic Limestones diagenesis (Paris Basin, France): Sedimentary Geology, v. 222, p. 161-180.
Buchbinder, B., Benjamini, C., Lipson-Benitah, S., 2000, Sequence development of Late Cenomanian–Turonian carbonate ramps, platforms and basins in Israel: Cretaceous Research, v. 21, p. 813-843.
Gertsch, B., Adatte, T., Keller, G., Tantawy, A.A.A.M., Berner, Z., Mort, H.P., Fleitmann, D., 2010, Middle and late Cenomanian oceanic anoxic events in shallow and deeper shelf environments of western Morocco: Sedimentology, v. 57, p. 1430-1462.
Kump, L.R., and Arthur, M.A., 1999, Interpreting carbon-isotope excursions; carbonates and organic matter: Chemical Geology, v. 161, p. 181-198.
Lipson-Benitah, S., Almogi-Labin, A., Sass, E., 1997, Cenomanian biostratigraphy and
palaeoenvironments in the northwest Carmel region, northern Israel: Cretaceous Research, v. 18, p. 469-491.
Sadooni, F.N., Howari, F., El-Saiy, A., 2010, Microbial dolomites from carbonate-evaporite sediments of the coastal sabkha of Abu Dhabi and their exploration implications: Journal of Petroleum Geology, v. 33, p. 289-298.
Saltzman, M.R., Runnegar, B., Lohmann, K.C., 1998, Carbon isotope stratigraphy of Upper Cambrian (Steptoean Stage) sequences of the eastern Great Basin; record of a global oceanographic event: Geological Society of America Bulletin, v. 110, p. 285-297.
Sass, E., and Bein, A., 1982, The Cretaceous carbonate platform in Israel: Cretaceous Research, v. 3, p. 135-144.
Sass, E., and Katz, A., 1982, The origin of platform dolomites: new evidence: American Journal of Science, v. 282, p. 1184-1213.
Segev, A., Sass, E., Ron, H., Lang, B., Kolodny, Y., McWilliams, M., 2002, Stratigraphic, geochronologic, and paleomagnetic constraints on Late Cretaceous volcanism in northern Israel: Israel Journal of Earth Sciences, v. 51, p. 297-309.
Segev, A., 2009, 40Ar/39Ar and K–Ar geochronology of Berriasian–Hauterivian and Cenomanian tectonomagmatic events in northern Israel: implications for regional stratigraphy: Cretaceous Research, v. 30, p. 810-828.
Sha, M.M., Nader, F.H., Dewit, J., Swennen, R., Garcia, D., 2010, Fault-related hydrothermal dolomites in Cretaceous carbonates (Cantabria, northern Spain): Results of petrographic, geochemical and petrophysical studies: Geological Society of France Bulletin, v. 181, p. 391-407.
Stein, M., Agnon, A., Katz, A., Starinsky, A., 2002, Strontium isotopes in discordant dolomite bodies of the Judea Group, Dead Sea Basin: Israel Journal of Earth Sciences, v. 51, p. 219-224.
Tritlla, J., Cardellach, E., Sharp, Z.D., 2001, Origin of vein hydrothermal carbonates in triassic limestones of the Espad´an Ranges (Iberian Chain, E Spain): Chemical Geology, v. 172, p. 291-305.
Young, S.A., Saltzman, M.R., Foland, K.A., Linder, J.S., Kump, L.R., 2009, A major drop in seawater 87Sr/86Sr during the Middle Ordovician (Darriwilian): Links to volcanism and climate?: Geology, v. 37, p. 951-954.
Postscript — on the preservation of animal tracks
Footprints from many creatures can be found throughout the fossil record, and the interpretation is typically very straightforward: some animal walked across a layered substrate (like mud, soil, ash, sand, etc.) when it was semi-soft, leaving an imprint. The weight of the animal disturbed the underlying layers, and the disturbance became preserved as more sediments were deposited over the top and the sequence was hardened into rock. Given the number of animals that have existed over Earth history (regardless of how old you believe it to be), footprints are relatively rare, however, as Dr. Snelling rightly predicts they should be. Why is this? Because other environmental factors are at odds with delicate footprints during the preservation process. If you want to test this, take a walk along the beach, and then reverse your path, trying to retrace your steps. Can you? More than likely, they will have been washed away by the constant wave action. Even in more stable environments (e.g. a lake shore, floodplain, desert), your tracks are only a small rainstorm away from being erased. Hence you can quickly appreciate the delicate conditions under which footprints might be preserved.
Before we move on, however, let us consider whether it is necessary to assume that all footprints would be “obliterated by wind and rain long before the prints were covered by new sediments and hardened into rock.” This reasoning seems valid, but is rooted in an oversimplification of the process. Footprints are not only preserved when they are exposed long enough to be slowly covered in sediments, while staying completely safe from wind and rain. The weight of the animal makes a depression in the underlying layers (even in only a few mm/cm deep), compacting them at the same time. This makes the imprint less susceptible to modification by wind and rain, particularly in moist, fine-grained sediments like mud and ash. In coastal environments, preservation can also be improved by cements that form early on from salts present in the water (especially carbonates and sulfates). Years later, the prints may no longer be recognizable at the surface, but are still present only a few centimeters below. Once the sediment is buried, turned into rock, uplifted, and weathered, the print will be exposed as a resistant pattern in the rock.
Note: If you’d like to try this in an experiment at home, fill an oven-safe container with salt water (add salt and baking soda to tap water). Fill the container halfway by slowly adding (and alternating) dry mud, clay, and/or fine sand until you have a distinct sequence of sediments. Let the concoction stand for a few days, remove the excess water on top, and then set the container outside, where it is subject to normal wind, sunshine, and rain. After it has set for a few more days, make an impression with your hand/foot. Leave the container for as long as you wish, so that it is exposed to normal weather conditions. When your patience runs out, place the container in the oven at 200-250°F for several hours, or until it is dry throughout. After it cools, you should be able to brush away the sediments, revealing the imprint in each layer. You’ll find that the experiment works better if the sediments are occasionally recharged with salt water (such as in a coastal environment), or in a semi-arid environment with regular rainstorms amid longer periods of dry heat. Enjoy!
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