Critique of Guy Berthault's "Stratigraphy"
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Through numerous laboratory studies, French young-Earth creationist (YEC) Guy Berthault claims to have discovered sedimentation properties that dispute several stratigraphic and relative dating principles used by modern field geologists. Although Berthault's hard work is very interesting, his knowledge of the sedimentology literature and stratigraphic field methods are decades or even centuries out of date. Because of his lack of knowledge, Berthault's experiments often involve "reinventing the wheel". When compared with Berthault, YEC Austin (1994, chapter 2 only) has a better understanding of these fundamental principles.
MISREPRESENTING MODERN INTERPRETATIONS OF STENO'S PRINCIPLES
Geologists use a number of principles to decipher the origins and interrelationships of sediment and sedimentary layers. Nicolaus (Nicholas) Steno originally derived many of these ideas in the 17th century. Berthault's descriptions of Steno's principles strongly resemble English translations (in Acrobat(R) Reader) of Steno's original works rather than the more refined definitions which field geologists now use. While it's usually a good idea to refer to the original definitions of terms and principles, individuals must remember that scientific and philosophical principles often evolve over time with advances in field and laboratory research. That is, YECs need to realize that modern scientists often use updated versions of old principles, such as Occam's Razor or Steno's Law of Superposition. The updated versions may substantially differ from the embryonic ideas of the original authors. Because Berthault criticizes Steno's original ideas rather than the modified principles used by modern geologists, his arguments are largely strawperson fallacies. That is, when Berthault attacks Steno's original definitions, he is simply recognizing deficiencies that geologists discovered long ago.
The Modern Principle of Superposition
The modern Principle of Superposition simply states that unless geologic materials have been overturned, folded or moved by faults, layered sediments or sedimentary rocks tend to be older than any sediments or sedimentary rocks directly above them. In the same way, before we can place the top layer on a cake, the bottom layer must already be there.
The time separating the formation of a sediment layer and the deposition of its overlying companion may range from seconds to billions of years. Large age differences between the two layers are especially common if an erosional plane (unconformity) exists between them. For example, a series of layers may be deposited in a shallow sea. Through a decline in sea level, perhaps because of the growth of glaciers, the layers may eventually be exposed to the atmosphere. Erosion may then remove many of the layers. Later, as the glaciers melt, sea level rises and the partially eroded layers submerge, a marine sediment layer may be deposited on top of the erosional surface. As stated in this example, an underlying layer that survived erosion MAY be fairly well solidified with calcite cement before the younger overlying layer is deposited. On the other hand, contrary to Berthault's description of the Principle of Superposition, the underlying layer need not be well "solidified" before overlying layers are deposited. The material only needs to be consolidated enough to receive an overlying layer without being mixed or destroyed. For example, a dust storm may deposit a layer of sediment on a prairie. Within months, grass may extensively grow on the dust layer. Another dust storm may then occur. Although plant roots may protect the underlying layer from wind erosion, another wind-blown layer of sediment might bury the prairie grass and its underlying layer. No geologist would argue that the underlying sediment is "solidified". However, plants or moisture may prevent its destruction and allow other sediments to bury it.
In the 1960s and 1970s, long before Berthault's research, geologists knew that laminae (layers of sediment or sedimentary rock each of which is less than one centimeter thick; Boggs, 1995, p. 109) can form under a variety of conditions, which may include rapid deposition (Boggs, 1995, p. 113-115; Harms and Fahnestock, 1965; Bouma, 1962). For example, sand laminae can form under high water velocities of about one meter/second (Boggs, 1995, p. 115, 51; Blatt et al., 1980, p. 136-146).
Turbidity currents are catastrophic sediment flows which often occur on sloping ocean or deep lake floors (Boggs, 1995, p. 68). They may result from earthquakes, unstable slopes, storms, volcanism or rivers pouring floodwaters into lakes and shallow seas. Turbidites are sediment deposits which result from turbidity currents. In 1962, Bouma extensively described the layering and other properties of turbidites (Boggs, 1995, p. 73). Bouma's (1962) descriptions included an idealize cross-section of a turbidite, which is now called a Bouma sequence (Boggs, 1995, p. 73). In general, coarser and denser materials settle first followed by layers of finer-grained materials as water turbulence subsides. The "B subdivision" of the Bouma sequence consists of upper-flow regime laminae (Boggs, 1995, p. 72-73, 115), which strongly resemble Berthault's laboratory results.
The deposition of Bouma sequences also refutes the idea that underlying layers must be well-solidified before overlying layers are deposited. In a turbidite, the layers may pile up in a matter of minutes (Baas et al., 2000). Indeed, any sediment deposited on ocean floors is expected to contain abundant water and may only have the consistency of thick pudding. The sediments may not substantially dewater and "solidify" (lithify) until they are buried at great depths. Because the underlying layers need not be well lithified to survive the immediate deposition of overlying sediments, the following statements by Berthault are nothing more than invalid strawperson arguments:
"Let's look at the first part of the definition of the principle of superposition - At the time when one of the highest stratum formed, the stratum underneath it had already acquired a solid consistence. A stratum between 50cm and one meter is considered as thick. Consequently, sub-marine drillings should encounter solid strata in the stratified oceanic sediments after a few meters. According to the report of Guy Pautot and Xavier Le Pichon entitled "Scientific results of the JOIDES programme": the first semi-consolidated sediments appeared about 300 metres (in depth)...(but) certain beds of chert (siliceous beds) have been found under only 100 metres of sediment. Stenon's [sic: Steno's] definition, therefore, relative to successive hardening, which extends greatly the total length of time of the deposit, is unsupported by the sedimentological observations mentioned above...[reference to animation omitted]." [Berhault's emphasis]
Nevertheless, surfaces of erosion (which often include flutes and other scouring features) are commonly present between various Bouma sequences (Boggs, 1995, p. 68-73, 449). That is, as a turbidite flow deposits a Bouma sequence, underlying sediments (which may include an earlier Bouma sequence) may be partially or largely eroded.
Again, the Principle of Superposition as geologists use it today says NOTHING about the underlying materials being rock solid when overlying layers are deposited. The materials only need to be consistent enough so that the deposition of overlying materials will not entirely erode and destroy them. Even if soft sediments are substantially eroded away, underlying less soft layers may be exposed, which will provide a foundation for the deposition of overlying layered sediments. Provided that the layers have not been overturned, folded or moved by later faults, the Principle of Superposition is still valid and the bottom layer is older.
The Modern Principle of Continuity
Berthault quotes the following antiquated definition of the Principle of Continuity:
"At the time when any stratum formed, either it was circumscribed on its sides by another solid body, or else it ran round the globe of the earth."
The modern description of the Principle of Continuity simply states that layers MAY extend over great lateral distances. IF so, the areal distribution of a layer may be followed and mapped. Of course, subsequent erosion may largely destroy a deposit and its original lateral extent may not be well defined.
Dr. David Plaisted and some other YECs expect the lateral extent of sedimentary layers to have been originally worldwide because of a supposed "Genesis Flood". However, geologists discarded this misconception long ago. Except for layers from a massive volcanic eruption or an asteroid impact (e.g., K-T iridium layer), individual geologic layers are not originally deposited on a worldwide scale. The deposition of individual layers is sometimes regional, but they're usually only localized. Even unusual, laterally extensive formations (such as the St. Peter Sandstone) actually consist of a series of local or regional sand deposits with distinctively different ages (Mintz, 1977, p. 31-35). Contrary to many YEC misconceptions, geologic formations usually do not have uniform ages.
When deposited, sediment layers may abut against topographic features, such as hillsides, shorelines or river channel banks. While Berthault mentions the importance of topographic barriers in limiting the lateral extent of sediment layers, he ignores another important factor. The material may simply pinch out because of a lack of sediment or inadequate transport by water or wind.
The Modern Principle of Original Horizontality
Freshly deposited sediment beds on continental shelves, sand dunes, deltas, hillsides and other slopes may dip significantly, often up to their angle of repose (for example, the foresets of deltas; Press and Siever, 2001, p. 233, 301). However, as recognized by the Principle of Original Horizontality, gravity dictates that loose sediments cannot be deposited vertically or at other steep angles.
Like his approach to the Bible, Berthault interprets the "horizontality" in this Principle too literally. He then proceeds to attack this fallacious strawperson interpretation with examples of freshly deposited sediments that are not absolutely horizontal. In reality, geologists recognized long ago that sediment layers may accumulate at orientations that are not absolutely horizontal. For example, G.K. Gilbert's fieldwork in the Pleistocene deposits of Lake Bonneville in 1885 demonstrated that foreset beds in deltas tend to slope (Boggs, 1995, p. 359-362). Cross-bedding in sand deposits is another common example involving non-horizontal deposition.
NON-UNIFORM DEPOSITIONAL RATES
Berthault also refers to outdated and erroneous statements by Charles Lyell, a 19th century geologist:
"In fact, Lyell added a fifth principle, giving as an example layers deposited in fresh water in Auvergne. Observing that the layers were less than a millimetre thick, he considered that each one was laid down annually. At this rate, the 230 meters thick deposit would have taken hundreds of thousands of years to form."
Berthault then proceeds to demolish this example of outdated Lyell uniformitarianism by demonstrating that thin layers may be rapidly deposited. Contrary to Berthault's strawperson argument, geologists now use actualism (modern uniformitarianism) and not Lyell uniformitarianism. We recognize that sediment deposition rates are rarely uniform. Under actualism, sediments may form slowly and gradually, catastrophically or from a mixture of these extremes. For example, the deposition of varves may be very consistent, but their thicknesses may vary with sunspot cycles and the Earth's orbital precession and eccentricity. As discussed above, laminar layers in turbidity currents (Bouma sequences; Boggs, 1995, p. 72-73) may form in a matter of minutes. Clearly, when individuals study a one-meter thick sandstone, they must recognize that many different origins are possible, which could range from slow sediment accumulation and erosion on a prehistoric beach to deposition in one night from an ancient hurricane. Often geologists cannot easily determine which scenario is most likely. Again, Berthault fails to understand these basic concepts and his views of stratigraphy, sedimentation and geology are clearly decades to centuries out of date.
RAPIDLY DEPOSITED LAMINAR VOLCANIC DEPOSITS
Besides laminae in turbidites, volcanic pyroclastics (especially surges) may also form catastrophic laminar beds that resemble the results in Berthault's experiments (Fisher and Schmincke, 1984, p. 107-115, 191, 192, 198-206, 247-256; Schmincke et al., 1973; Carey, 1991). That is, mixtures of air, volcanic ash, coarser volcanic debris and perhaps water may violently cascade down the sides of some volcanoes and produce laminar deposits. For example, long ago Schmincke et al. (1973) discussed the presence of laminar- and cross-bedding in a pyroclastic deposit at Laacher See, Germany. Many of the features seen in pyroclastics (such as cross-bedding, antidunes and laminar features) resemble those seen in Bouma sequences (Schmincke et al., 1973; Fisher and Schmincke, 1984, p. 107-115). On the other hand, laminae and cross-beds may also slowly form in quiet, gradually changing sedimentary environments (Blatt et al., 1980, p. 133-135). Again, actualism is flexible and allows for both NATURAL catastrophic deposits and slow and gradual deposition.
In his Figure 7 under "Stratification", Berthault explains how the lateral migration of sediment particles may produce graded and dipping beds. However, this concept is not new and closely resembles the delta profile diagrams in ordinary stratigraphy and sedimentation textbooks, such as Boggs (1995, Figure 14.9, p. 504; Figure 14.12, p. 512). Also, contrary to Berthault's claims, Steno's Law of Superposition is not violated in his Figure 7B. In the VERTICAL direction, the overlying materials are still younger than (were deposited after) the underlying materials.
From his discussions of his Figures 7 and 2 ("Exxon Systematics"), Berthault seems to realize that lithologically uniform beds of sediment do not necessarily have uniform ages. Again, this concept is not new. Berthault has rediscovered the fundamental differences between rock and time correlation, which have been presented for many decades in most undergraduate historical geology textbooks (e.g., Mintz, 1977, chapter 9).
DEPOSITION OF THE TONTO GROUP
In A New Approach, Berthault attempts to "apply" his principles to explain how the Tonto Group of the Grand Canyon region could hypothetically form during "Noah's Flood". The ideas and diagrams are largely taken from Austin (1994, p. 67-70).
The Tonto Group of the Grand Canyon region consists of the Tapeats Sandstone, Bright Angel Shale and Muav Limestone. According to Berthault, geologists conclude that the formations represent at least 70 million years of deposition. Detailed reviews of the geology of these and associated formations at Young Earth Creationism and the Geology of the Grand Canyon: Part 1: The Geology of the Colorado Plateau and Van Till et al. (1988, chapter 6) demonstrate that their origins are incompatible with a rapid and violent "Genesis Flood". For example, the Bright Angel Shale contains a number of thin, but coarse-grained, conglomerates. While such features could periodically develop over geologic time, how could these gravelly layers form in the MIDDLE of Berthault's rapid "Flood-based sediment sorting process"? Furthermore, there are sections of the Bright Angel Shale where the materials become coarser rather than finer moving UPWARD in the formation. How is this consistent with the origin of "Zone 5" in Austin and Berthault's Figure 14? Fossils of brachiopods and other sessile animals are also present in the Tonto Group. How could organisms live and build burrows in such rapidly deposited sediments? Also, if "Noah's Flood" transported the brachiopods into the formations, how would relatively large brachiopods get sorted with finer grained sediments? Why aren't they with the gravels? In contrast to the oversimplified and inadequate explanations for the origin of the Tonto Group provided by YECs Berthault and Austin (1994), Strahler (1987, chapter 31) and "Young Earth Creationism and the Geology of the Grand Canyon" by Jon Woolf contain accurate and detailed descriptions of the geologic history of the Canyon.
Most of Berthault's "discoveries" are not new. Although Berthault's hard work is very interesting, he and his YEC colleagues are often unaware that geologists knew about these "discoveries" in sedimentology and field geology decades or even more than a century ago. In other cases, Berthault's ideas (such as his comprehension of Steno's Principles and uniformitarianism) are grossly outdated. Because YECs Berthault and Austin's views of the geological properties of the Tonto Group lack sufficient detail, their "Flood model" utterly fails to explain the origin of the Group.
Austin, S. A. (ed.), 1994, Grand Canyon: Monument to Catastrophe, Institute for Creation Research, Santee, CA, 92071.
Baas, J.H.; R.L. van Dam and J.E.A. Storms, 2000, "Duration of Deposition from Decelerating High-density Turbidity Currents", Sed. Geol. v. 136, p. 71-88.
Blatt, H.; G. Middleton and R. Murray, 1980, Origin of Sedimentary Rocks, 2nd edition, Prentice-Hall, Inc. Englewood Cliffs, NJ 07632.
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Theotokos Catholic Books - Creation/Evolution Section - www.theotokos.org.uk