Geological Evidence for Noah's Flood?
A Rebuttal of Walter Brown's Flood Geology

Claim 1:

Many sedimentary layers can be traced over hundreds of thousands of square miles. On the other hand, river deltas, which are the most significant example of sedimentation we see today, are only a tiny fraction of that area. Liquefaction during a global flood accounts for the vast lateral expanses of layers. Current processes and eons of time do not.

Some thick and extensive sedimentary layers have remarkable purity. The St. Peter sandstone, spanning about 500,000 square miles in the central United States, is composed of almost pure quartz, similar to the sand on a white beach. It is hard to imagine how any process, other than global liquefaction, could achieve this degree of purity over such a wide area. Almost all other processes involve mixing, which destroys purity (Walt Brown).

Rebuttal

Brown claims that river deltas are the most "significant example of sedimentation we see today," and that *no* currently operating processes can produce sedimentary layers extending over thousands of square miles. This is not just wrong -- but laughably so. Sedimentation on continental shelves is producing "sedimentary layers can be traced over hundreds of thousands of square miles." Ever heard of the Gulf of Mexico, the Altantic Shelf?

There are also continental sedimentary deposits forming today that cover "hundreds of thousands of square miles." For instance, the Sahara Desert occupies about 3.3 million square miles, and about 660,000 miles of that area is covered by quartz sand deposits. This is even bigger than Brown's own example. The Congo River drainage basin, to take another example, laterally extends over 1,335,000 square miles. This depositional system is "not only vast but is also—with the exception of the sandy plateaus in the southwest—covered with a dense and ramified network of tributaries, subtributaries, and small rivers." These tributaries "meander" across a broad, flat flood plain over time, depositing fluvial sediments much like those we find in ancient fluvial systems. In fact, the Congo system is probably much bigger than most fluvial system deposits in the geologic record, such as the Chinle Formation.

The St. Peter Sandstone covers an area of about 325,000mi2, not 500,000 (Dapples, 1955. General Lithofacies Relationships of St. Peter and Simpson groups AAPG Bulletin 39:4, p. 454). Of course, this is still a very extensive deposit. Although the lithology of the St. Pete is notably 'pure' over a wide area, it is not "pure" in any absolute sense, as beds of marine limestone are present in the middle and upper parts of the formation in extreme northern and southwestern Illinois, Iowa, Arkansas, and Oklahoma. Marine fossils occur in some of these limestone beds. Outcrops from Missouri preserve trace fossils and evidence of bioturbation.

How could it have formed? During the Ordovician, there was in fact a "global flood" of sorts, one of many seperate sea-level fluctuations during the Phanerozoic. The reason the sand looks "similar to sands on a white beach" is because that's basically what it is. Sandy beachs are sandy because coastal processes and weathering destroy or suspend basically everything except quartz. When sea level rose in the Ordovician, the coastal zone moved progressively inland. As it did, it reworked whatever sediments happened to be exposed at the surface, depositing them as typical near-shore sandstones, much the same way that the Tapeats sandstone was deposited in the Grand Canyon region during the Cambrian transgression.

Looking for information, I found this interesting piece of information.

"The contact between the St. Peter Sandstone and the older sedimentary rocks upon which it rests is another major unconformity or erosion surface like the one that underlies the Pennsylvanian rocks. After deposition of the Lower Ordovician strata, crustal movements raised the mid-continent region above sea level, and a long interval (about 15 million years), occurred during which erosion cut deeply into the rocks exposed at the surface and there was widespread development of solution features (karst topography). There is evidence that a river system drained across northern Illinois from the northeast and cut deep channels into the bedrock surface. In northern Illinois and southern Wisconsin, the lower Ordovician strata were completely removed from the flanks of the Wisconsin Arch in many places. The erosion interval ended in the Middle Ordovician when the mid-continent region was lowered below sea level again and the ocean again spread over the region. The clean, well sorted sand that became the St. Peter Sandstone was deposited on the erosion surface where Lower Ordovician and Cambrian rocks were exposed. The St. Peter is generally less than 200 feet thick, but where the sand filled ancient river channels, it is locally as much as 500 feet thick" (Guide to the Geology of Buffalo Rock and Matthiessen State Parks Area, La Salle County, Illinois. ISGS, 1997).

Given that most flood theories propose that the continents remained inundated throughout the 'Paleozoic,' I wonder how such evidence (karst topography, deeply incised fluvial channels) can be explained?

Claim 2:

Sedimentary layers usually have boundaries that are sharply defined, parallel, and nearly horizontal. Thin, sharply defined layers are sometimes stacked vertically, thousands of feet deep. If each layer had been laid down thousands of years apart, erosion would have destroyed this parallelism. Again, liquefaction explains this common observation. (Walt Brown).

Rebuttal:

Take a closer look at those bedding planes. On many of them you will find tracks, trails, burrows, and borings. In other words, extensive evidence for bioturbation. These prove that, for some minimum amount of time, each bedding plane remained exposed at the sediment-water interface, with organisms burrowing through the sediment, crawling across its surface, and so forth. The borings are important becase they clearly indicate a *hardened* substrate. On other bedding planes, you might find successive layers of mudcracks, or sandstone foresets with raindrop impressions. On other bedding planes ('hardgrounds'), you will find a whole ensemble of organisms preserved *in situ.* In these cases, it can be said confidently that one layer was deposited, sedimentation stopped, the sea-floor hardened, and was then colonized by organisms which bored into the surface and *then* grew to adult size. This clearly refutes Brown's proposed scenario.

Claim 3:

Varves are extremely thin layers which evolutionists claim, without much justification, are laid down annually in lakes. By counting tens of thousands of varves, they believe elapsed time can be determined. However, since varves are so uniform, show no evidence of the slightest erosion, and are deposited over wider areas than tiny "stream deltas," they are better explained by liquefaction. PREDICTION 14: If representative corings are taken in the bottom of any large lake, they will not show laminations as thin, parallel, and extensive as the varves of the Green River formation. (Walt Brown).

Rebuttal:

Creationists are correct to question the interpetation of any given couplets as varves. Couplets have often been referred to as varves when the evidence for such a claim is lacking. Couplets cannot be designated "varves" simply because they are thin couplets. We know that algal bloom couplets, for instance, can in some cases be produced biannually. That being said, it can be said with great confidence that many couplets in the fossil record are in fact varves [see below].

However, in proposing his own explanation of the GRF couplets, Brown makes yet another claim that can be easily refuted by examining the published literature on the GRF. First of all, mere size in itself has little if anything to do with determining whether or not a sedimentary deposit in the geologic record can be explained in terms of a known depositional process. Second, varves are by definition couplets that are deposited as a result of a yearly cycle. The couplets in the Green River Formation consist of a thin lamina of organic rich kerogen, overlain by a thin lamina of carbonate. Toward the basin margins, these couplets grade into grade into algal, ostracodal, gastropodal, and bioturbated calcimicrites (Rubey, Oriel, and Tracey, 1975; Buchheim, 1994). The idea that at least some of the Green River couplets are in fact annual deposits is supported by several observations, both in the formation itself and in analogous modern lake environments. First we will discuss the evidence from the Green River Formation itself:

1. There are periodic changes in thickness of the couplets that correspond well to known climatic cycles. This is at best an unexpected consequence of the liquefaction scenario. I don't know of any hydraulic mechanisms that could produce these cyclic features. Ripepe et al. write:

"On the premise that sequential changes in varve thickness offer a proxy for climatic variations, we investigated varve thickness in three core segments from the distal lacustrine oil shales (Tipton and Laney members) of the Green River Formation, by means of an image analysis program. Of two strong bimodal periodicities one, at 4.8-5.6 years, is interpreted as an El Nino type (ENSO) phenomenon of atmospheric dynamics, while the other, at 10.4-14.7 years, is interpreted as the sunspot cycle, originally recognized in this formation by Bradley (1929,1931). Weaker periodicities may exist at ca.8 and 33 years - the latter also recognized by Bradley. Taken in conjunction with the work of Bradley (1929,1931) and of Crowley et al. (1986), this suggests that some but not all of the oil shale of the Green River Formation is truly varved and can be used to infer climatic time-series." Maurizio Ripepe, Lillian t. Roberts, and Alfred G. Fischer, Enso and Sunspot Cycles in Varved Eocene Oil Shales from Image Analysis, Journal of Sedimentary Petrology, 61:7, December, 1991, p. 1155.

See also: Alfred G. Fischer and Lillian T. Roberts, Cyclicity in the Green River Formation (Lacustrine Eocene) of Wyoming, Journal of Sedimentary Petrology, 61:7, December 1991, p.1147.

2. A 55 meter interval had a volcanic tuff above it and below it and each tuff was dated. The top of this section dates at 46.2 million years and 55 meters lower dates 47.2 million years. Taken at face value, this suggests an avergae depositional rate of about 0.055mm/year (Robert R. Remy, Stratigraphy of the Eocene Part of the Green River Formation in the South-Central Part of the Uinta Basin, Utah, U.S. Geological Survey Bulletin 1987, p. BB20). The averaged thickness of the couplets is in fact about 0.06mm. If Brown's theory is correct, this can only be an improbable coincidence.

3. The Green River formation contains mudcracks and salt casts, within the Wilkins Peak Member, sandwiched between the Tipton and the Laney members, which would not form via a liquefaction process. Several apparent Presbyornis nesting-sites, as well as the trackways of these birds, have been reported in shoreline facies within the Green River Formation (Leggitt and Buchheim, 1997; McGrew, 1980). Obviously one would not expect birds to be building nests or walking around under water.

Claim 4a:

Dead animals and plants quickly decay, are eaten, or are destroyed by the elements. (Walt Brown).

Rebuttal:

An obvious oversimplification. Whether or not dead animals and plants decay "quickly" depends entirely on the environment in which the dead plant of animal ends up. For instance, marine or fresh-water animals which die in a basin with anoxic bottom waters, decay is extremely slow and predation is virtually absent because of the lack of oxygen. The "bog people" in England and the desert mummies of Peru are still well preserved despite having died 2000 years ago.

Quick burial is of course one of the ways organisms make in into the fossil record, in in some cases it is the best explanation. This is a perfectly normal phenomena that can be observed to occur in the modern world, is well known to geologists, and does not in any way imply that Noah's flood created the geologic record. I don't think there's a geologist anywhere in the world that would deny that tsunamis, landslides, turbidity flows, floods, hurricanes, volcanic eruptions, etc. occured in the past just as they do today, occasionally resulting in the rapid burial of unlucky organisms. The point is that the quality of preservation does not necessarily demand rapid deposition, and individual cases must be examined to see what explanation is better supported.

Claim 4b:

Their preservation as fossils requires rapid burial in sediments thick enough to preserve their bodily form. This rarely happens today . . . Liquefaction provides a mechanism for the rapid burial of trillions of fossils in appropriate layers. (Walt Brown).

Rebuttal:

If Noah's flood deposited the entire geologic record in weeks or months, then we would expect *all* fossils to show evidence of rapid burial, which is certainly not the case. To take one example: conodonts. Condonts are tiny jaw-like bones about the size of a grain of sand. There are hundreds of different species named on the basis of apparatus morphology. They occur in marine deposits all over the earth from the mid-Cambrian to the late Triassic, and are one of the most widely-used zonal fossils in Paleozoic stratigraphy. There are a gazillion of these things in Paleozoic marine sediments. Despite their omnipresence in the fossil record, no one knew what the conodont animal looked like because no one had ever found an articulated condont animal before. In 1983, the articulated animal was finally discovered from the Carboniferous of Scotland. A handful of other examples have been found since, and we now know that the conodonts were tiny eel-like animals. So the fossil record of condodont "body forms" is overwhelmingly characterized by poor preservation, despite the fact that flood geology requires that *all* of the gazillions of condonts were buried extremely rapidly in the initial phases of the flood.

Finally, it is a clearly not the case that condonts --or any of the well-known zonal fossil groups, such as forams, trilobites, or ammonites-- are sorted in a sequence consistent with "liquefaction." Note that Brown simply claims that liquefaction can produce the required results -- nowhere does he attempt to explain the actual data of the fossil record in terms of this theory.

Let's consider a couple of test cases, using actual stratigraphic data, and see how well "liquefaction" fares an explanation. How does "liquefaction" explain the stratigraphic distribution of Ammonites during the Jurassic? This would be a perfect test case for the liquefaction scenario. Below is a list of the Jurassic stages and their corresponding zonal Ammonites, as observed throughout northwest Europe. Data is from Arkell (1956, p. 10-11). Arkell states that "From the Hettangian up to the Middle Kimeridgian these stages can be recognized all over the world, but after that the scheme breaks down owing to regional differentiation of faunas" (p. 8).

Are these widespread zonal fossils sorted on the basis of hydrodynamic characteristics, as Brown and other creationists propose? Not at all. They are sorted not by size or any other hydrodynamic features. Instead, they are sorted in an "apparent" (?) evolutionary sequence! Raymond Moore (1933, p. 483-484) writes

"The sutures (junction of the shell partitions with the inner wall of the shell) are only moderately curved or angulated in the simplest amminoids. This type was characteristic of the later Paleozoic rocks but some of the amminoids of the Triassic are little, if any, more advanced. An increased number of bends and angles in the suture line, accompanied by a progressive complication in pattern, marks the development of most of the Mesozoic ammonoids. In many cases the suture pattern is so intricate that it is indeed difficult to trace. The diversity is amazing, but each type of suture is constant according to genus and species. Because even slight changes in the sutures are readily determinable and with other characters permit definite recognition of specific differences, these shells are well fitted to serve as markers of stratigraphic zones and of geologic time."

Another good test case for Brown and the flood geologists is the stratigraphic distribution of graptolites in lower Paleozoic marine sediments. Graptolites were tiny colonial organisms thought to be related to the hemichordates. Their remains are particularly abundant in Ordovician and Silurian sediments. They disappear from the fossil record in the early Carboniferous, although some living pterobranch species are similar to them in some respects. Some where benthic, living attached to a substrate, and some were planktonic. Their "skeletons" were composed of a chitin-like protein, which is often found as carbonized impressions on bedding planes. The actual graptolite animals lived in tiny tubes called thecae.

The distribution of graptolites in the fossil record has been meticulously studied by biostratigraphers. Clifford Cuffey writes:

"At a more detailed level, the development of Ordovician graptolite biostratigraphy in North America provides a good case study of biostratigraphic methods based on faunal succession (Berry, 1977), and one that is independently testab le (Goldman et al., 1994; Mitchell et al., 1994). Fifteen graptolite biozones have been recognized, defined, and refined by nearly a century of detailed work. Based on superpositional order, the same succession of graptolite species and zones is recognized in New York (Ruedemann, 1904, 1908, 1912, 1925, 1947; Berry, 1962, 1963, 1970; Mitchell et al., 1994; Goldman et al., 1994), Quebec (Riva, 1969, 1974), Newfoundland (Kindle & Whittington, 1958; Whittington & Kindle, 1 963), west Texas (King, 1937; Berry, 1960; Bergstrom, 1978), Yukon (Jackson, 1964; Jackson & Lenz, 1962), and east-central Alaska (Churkin & Brabb, 1965). Moreover, isolated localities with only short stratigraphic sections can be compared with portions of the zonation defined elsewhere (Ross & Berry, 1963). No assumption of evolution was made. The fact that this same succession occurs repeatedly in different regions all over North America, and that the succession can be independently verified by anyone willing to recollect the localities, leads to the conclusion that geochronologic correlation based on biostratigraphy is valid.

"This conclusion can be independently tested. The Middle Ordovician Trenton Group and Utica Formation of New York contain three of the graptolite zones and also contain numerous K-bentonite beds (Goldman et al., 1994; Mitchell et al., 1994). Because the K-bentonite beds are volcanic ash-falls, they represent geologically instantaneous isochrons. Furthermore, trace element geochemistry of their contained volcanic glass distinguishes each K-bentonite bed, assures proper co rrelation, and establishes a geochronologic framework to which the graptolite zones can be compared (Goldman et al., 1994; Mitchell et al., 1994). Indeed, the graptolite zone boundaries are parallel with the K-bentonite beds, therefore indep endently corroborating graptolite zones as time-parallel (Goldman et al., 1994; Mitchell et al., 1994). This independently demonstrates the validity of biostratigraphy on a local scale, and corroborates its use as a method of geochronologic correlation [The Fossil Record: Evolution or "Scientific Creation"? emphasis mine].

As with the Jurassic ammonites, Brown should explain how a global flood could perfectly sort graptolites into a consistent vertical sequences over an area of thousands of square miles, despite the fact that they all would have possessed very similar hydrodynamic properties.

Claim 5:

The absence of meteorites in deep sediments is consistent only with a rapid deposition of all the sediments. (Walt Brown).

Meteorites of various types are continually plunging into the earth's atmosphere from outer space, and some reach the surface. Supposedly this has occurred for billions of years with more falling in the earlier ages of earth history than in recent time. Yet no meteorites have been discovered in the deeper and supposedly very old sedimentary strata, but only in the upper, recent strata. Does this not strongly suggest that most of the sedimentary strata were laid down rapidly over a short period of time so that very few meteorites could be deposited in them? (The Creation Explanation)

Rebuttal:

Impact products, impact craters, and even actual meteorites have been found buried in "deep sediments," thus this claim is directly falsified. The evidence in this case clearly and overwhelming refutes the creationists. To take one, well known example. At the K-T boundary, there is a) an 180km wide crater of exactly the right age, b) impact generated products such as melt sperules, microdiamonds, and shocked minerals are found in well over 100 K-T boundaries, in both continental and marine sediments (Glen, W. 1994. The Mass Extinction Debates. Stanford Unoversity Press, p. 9), and c) an actual small chunk of the probable meteorite itself recovered from an ocean core of the K-T boundary (Kyte, F.T. 1998. A meteorite from the Cretaceous/ Tertiary boundary. Nature 396: 237-239).

Though the K-T is probably the best studied impact event, there are many more examples, and still more subsurface examples will surely be discovered in the future. Examples that immediately come to mind are the Ries Crater in Germany (24km), the Siljan Crater in Sweden (55km), the Manicouagan Crater in Quebec (~199km), the Vredefort Crater in South Africa (`140km), and the Sudbury Crater in Ontario (`200km!). These are just a few of the craters that have been well-studied. Grieve and Robertson (The Terrestrial Cratering Record, Icarus, Vol.38, No.2. 1979, pp.212-229) list dozens of Phanerozoic impact craters. A more recent list can be found here. And this represents only the continental record of impact; we can be confident that this represents only a small portion of the total number of impacts which actually occured, since craters are much less likely to be preserved or even located in ocean basins. I was surprised to find that an impact crater has been discovered in Middlesboro, KY, about an hour from my home in Louisville. See also:

Koeberl, C., Reimold, W. U., and Brandt, D., 1996b, Red Wing Creek structure, North Dakota: Petrographical and geochemical studies, and confirmation of impact origin. Meteoritics and Planetary Science, v. 31, 335-342.

Koeberl, C., Poag, C.W., Reimold, W.U., and Brandt, D., 1996c, Impact origin of Chesapeake Bay structure and the source of North American tektites: Science, v. 271, p. 1263-1266.

Pilkington, M., and Grieve, R. A. F., 1992, The geophysical signature of terrestrial impact craters: Reviews of Geophysics, v. 30, p. 161-181.

Poag, C. W., Powars, Poppe, L. J., and Mixon, R. B., 1994, Meteoroid mayhem in Ole Virginny: Source of the North American tektite strewn field: Geology, v. 22, p. 691-694.

H. B. Sawatzky, Astroblemes in Williston Basin, Bulletin American Association Petroleum Geologists, April 1975, p. 694-710.

J. G. Spray et al., 1998. Evidence for a late Triassic multiple impact event on Earth. Nature 392, 171 - 173

P. M. Vincent, and A. Beauvilain, The Circular Structure of Gweni-Fada, Ennedi: A New Meteorite Impact Crater in Northern Chad, Compt. Rend. Ser. 2, Sect. A. v. 323(1996):12:987-997

There are several additional confirmed examples of impact products such as tectite strewn fields, shocked minerals, and even actual meteorite material in the fossil record, again directly contradicting the creationist assertion. Here are just a few sources describing such finds:

P. Claeys. 1994. Microtektite-like Impact Glass associated with the Fransnian-Famennian Boundary Mass Extinction, Earth Planetary Science Letters. 122:3-4 , p 303-315.

Clymer, A. K., D. M. Bice, A. Montanari. 1995. Shocked quartz in the Late Eocene: bolide impact evidence from Massignano, Italy. 4th International Workshop on Impact and Evolution of Planet Earth, pp. 60.

B.P.Glass and C. Koeberl. 1999. ODP Hole 689B spherules and upper Eocene microtektite and clinopyroxene-bearing spherule strewn fields. Meteoritics & Planetary Science 34.

Henderson, E. P., and Cooke, C. W., 1942. The Sardis (Georgia) meteorite. Proc. U.S. National Museum, 92:141-150.

Izett, G. A., Cobban, W. A., Obradovich, J. D., and Kunk, M. J., 1993, The Manson impact structure: ⁴⁰Ar-³⁹Ar age and its distal impact ejecta in the Pierre shale in southeastern South Dakota: Science, v. 262, p. 729-732.

Kerr, Richard A., 1996. A piece of the dinosaur killer found? Science, v. 271, 29 March 1996, p. 1806.

Koeberl, C., and Shirey, S. B., 1993, Detection of a meteoritic component in Ivory Coast tektites with rhenium-osmium isotopes: Science, v. 261, p. 595-598.

Koeberl, C., Masaitis, V. L., Langenhorst, F., Stöffler, D., Schrauder, M., Lengauer, C., Gilmour, I., and Hough, R. M., 1995, Diamonds from the Popigai impact structure, Russia: Lunar and Planetary Science, v. XXVI, p. 777-778.

Leroux, H., Reimold, W. U., and Doukhan, J. C., 1994, A T.E.M. investigation of shock metamorphism in quartz from the Vredefort dome, South Africa: Tectonophysics, v. 230, p. 223-239.

Leroux, H., J. E. Warme, and J. C. Doukhan. 1995. Shocked quartz in the Alamo breccia, southern Nevada: evidence for a Devonian impact event. Geology. vol. 23, pp. 1003-1006.

Nyström, J. O., Lindström, M., and Wickman, F. S. 1988. Discovery of a second Ordovician meteorite using chromite as a tracer. Nature, 336:572-574.

Schmitz, B., Lindstrom, M., Asaro, F., and Tassinari, M.. 1996. Geochemistry of meteorite-rich marine limestone strata and fossil meteorites from the Lower Ordovician at Kinnekulle, Sweden. Earth and Planetary Science Letters. volume 145, pp. 31-48.

P. Thorslund, F. E. Wickman and J. O. Nystrom, 1984. The Ordovician Chondrite from Brunflo, Central Sweden, I, General Description and Primary Minerals, Lithos, 17, p. 87.

W. Wei, 1995. How Many Impact-Generated Microspherule Layers in the Upper Eocene? Palaeogeography, Palaeoclimatology, Palaeoecology. 114:1, pp. 101-110.

Yudin, I. A., 1971. Relict structures of stony meteorites in a Mesozoic formation of the central Urals. Meteoritics, 6: 99-103.

Impact products have also been found in very old sediments of Proterozoic and Archaean age.

Shoemaker, E.M., Shoemaker, C.S.. The Proterozoic impact record of Australia. AGSO J. Aust. Geol. Geophys. 16 (1996) 379-398.

Glikson, A.Y., 1999. Oceanic mega-impacts and crustal evolution. Geology, 27:387-341.

Byerly, G. R., Lowe, D. R., 1994. Spinels from Archaean impact spherules: Geochim. et Cosmochim. Acta, 58:3469-3486.

Shukolayukov, A., Kyte, F.T., Lugmair, G.W. and Lowe, D.R., 1998. The oldest impact deposits on Earth - first confirmation of an extraterrestrial component (abstract), Cambridge meeting on Impacts and the Early Earth.

Simonson, B.M., 1992. Geological evidence for an early Precambrian microtektite strewn field in the Hamersley Basin of Western Australia. Geol. Soc. Am. Bull., 104, 829-839.

Simonson, B.M. & Hassler, S.W., 1997. Revised correlations in the early Precambrian Hamersley Basin based on a horizon of resedimented impact spherules. Aust. J. Earth Sci., 44, 37-48.

Discovery of a layer of probable impact melt spherules in the Late Archaean Jeerinah Formation, Fortescue Group, Western Australia. B. M. Simonson, D. Davies and S. W. Hassler. Australian Journal of Earth Sciences 47 (2), 315-325. Geological Society of Australia.

Glikson, A.Y., 1996, Mega-impacts and mantle melting episodes: tests of possible correlations. Australian Geological Survey Organisation Journal,16/4:587-608.

So in fact one could safely abandon Noah's flood as an explanation for the geologic record on the basis of impact phenomena alone, since there is no known mechanism that could concentrate so many bolide impacts into the mere weeks or months of the flood. And even if there were such a mechanism, it would be downright laughable to assert that Noah and family could surivive such an interval of heavy bombardment.

Claim 6:

In the Grand Canyon, the Precambrian-Cambrian interface is an almost flat, horizontal surface that is exposed for 26 miles above the Colorado River. The layers above the Precambrian-Cambrian interface are generally horizontal, but the layers below are tipped at large angles, and their tipped edges are beveled off horizontally. It appears that, as slippage began during the compression event, the layers below the slippage plane continued to compress to the point where they buckled. The sliding sedimentary block above the slippage plane beveled off the layers that were being increasingly tipped. (Walt Brown).

Rebuttal:

If I understand Walt Brown's scenario correctly, and I very well may not, he is saying that the block-faulting of the Grand Canyon Supergroup is the result of *compression* at the beginning of the flood. Actually, the block faulting is the result of crustal extension, not compression!

"The Grand Canyon Supergroup records at least two distinct periods of intracratonic extension and sedimentation in the late Mesoproterozoic and Neoproterozoic. New ⁴⁰Ar/³⁹Ar age determinations indicate that the Mesoproterozoic Unkar Group was deposited between ca. 1.2 and 1.1 Ga. Basins in which the Unkar Group was deposited and the related northwest-striking faults were created by northeast-southwest extension, which was contemporaneous with regional northwest-southeast “Grenville” contraction. New U-Pb data indicate that the Neoproterozoic Chuar Group was deposited between 800 and 742 Ma. Sedimentary and tectonic studies show that Chuar deposition took place during east-west extension and resulting normal slip across the Butte fault. This event is interpreted to be an intracratonic response to the breakup of Rodinia and initiation of the Cordilleran rift margin" (J. M. Timmons et al., Proterozoic multistage extension recorded in the Grand Canyon Supergroup and establishment of northwest- and north-trending tectonic grains in the southwestern United States. GSA Bulletin: Vol. 113, No. 2, pp. 163–181; See also: Karl E. Karlstrom et al., Chuar Group of the Grand Canyon: Record of breakup of Rodinia, associated change in the global carbon cycle, and ecosystem expansion by 740 Ma. Geology: Vol. 28, No. 7, pp. 619–622.).

The block-fault structural style of the GCS is basically identical to extensional structures in the Basin and Range province and on the Atlantic margins (Sears, p. 80). And although the Precambrian surface was extensively weathered and mostly displayed low relief (simply geometry of the blocks shows that up to 12,000ft was removed in some places), it was not *literally* 'beveled' as Brown implies! [The illustration on Brown's page shows a literally flat surface] In fact, ridges or hogbacks of Shinumo Quartzite still rose up to 600ft above the land surface (p. 79). Here is how Middleton and Elliot describe the "Precambrian-Cambrian interface" of the Grand Canyon region:

"The surface upon which the Tonto Group accumulated was quite irregular. It was characterized by a rolling topography of resistant bedrock hills and lowlands. The Precambrian bedrock was weathered extensively in places and eroded during long periods of subarial exposure. . . There are numerous places in the Canyon where the Tapeats Sandstone thins across or pinches out against these Precambrian highs. Where the Tapeats pinches out, the Bright Angel Shale overlies the Precambrian surface" (p. 86).

They go on to note that the Precambrian bedrock shows signs of extensive chemical weathering (Sharp, R.P. Ep-Archaen and Ep-Algonkian Erosion Surfaces, Grand Canyon, Arizona. GSA Bulletin, vol. 51, pp. 1235-1270. 1940). This is an important point because it shows that block-faulting in the Grand Canyon region did not *immediately* precede the flood (Cambrian transgression). This regolith, which is up to 50ft thick in places, indicates that the block-fault mountains were eroded subarially for a long period of time before being buried by Cambrian sediments. This is fully expected given that there was an estimated 200my or so between the block faulting/extension event and the Cambrian transgression.

I should also point out that the Precambrian strata in the Grand Canyon region show evidence of many *successive* tectonic influences, both compressive and extensional. In the Vishnu Complex underlying the GCS, there is evidence of at least two distinct episodes of compression and pluton emplacement. This occurred, and the surface of the Vishnu was deeply eroded, before the first GCS sediments were deposited. The 12,000ft GCS accumulated on a subsiding continental margin, which apparently persisted for a long time. Towards the end of the Precambrian, the Grand Canyon region experienced extensional tectonics, and this resulted in the block faulting of the Precambrian formations. This is thought to have occurred during a rifting event about 200my before the Cambrian, but the timing of the event is not well constrained. These block fault structures are seen along the Atlantic margins as well, were they were generated by rifting/extensional tectonics as the Atlantic basin opened in the mesozoic.

[To be continued . . .]