The GeoChristian

The Earth. Christianity. They go together.

Six bad arguments from Answers in Genesis (Part 3)

This is part three of a six-part series examining supposed evidences for a global flood that have recently appeared on the Answers in Genesis web site.
The people at AiG are my brothers and sisters in Christ, and I share their love for the Lord Jesus Christ, their respect for the Bible as the Word of God, and their desire to see people come to faith in Christ. However, I view their arguments for a young Earth and geological catastrophism as unnecessary Biblically, bad apologetics, and a serious obstacle to the evangelism of scientists.
Unfortunately, few people in our churches or Christian education system have the geological background to critically analyze these arguments. The result is that people read articles like these from AiG, find them to be rather impressive, and believe that these present sound arguments in defense of the Bible. The opposite, however, is true. A vast majority of Christian geologists find the arguments for a young-Earth and the geologic work of the Flood to be untenable. It is my strong opinion that the young-Earth arguments of organizations like AiG have no place in our churches and Christian education system.
Part one examined the young-Earth creationist (YEC) argument that fossils at high elevations are proof of a global flood.
Part two examines the YEC argument that sedimentary rocks that contain dense accumulations of fossils can best be described by the action of Noah’s Flood.
Part three — this article
Part four looks at the YEC claim that long-distance transport of sand grains can only be explained by Noah’s flood.
Part five looks at unconformities and the boundaries between geological formations. The young-Earth crowd claims that there is no evidence for weathering and erosion between layers, which is simply not true.
Part six looks at whether or not layers must be soft rather than lithified in order to fold. Laboratory and field evidence indicate that solid rocks really can fold.
Credit: USGS

Stratigraphy of Grand Canyon National Park showing the position of the Tapeats Sandstone and Redwall Limestone.Credit: USGS

Flood evidence number three” from Answers in Genesis is called “Transcontinental Rock Layers.” In this article, young-Earth creationist Andrew Snelling describes sedimentary rock layers that cover large areas of continents, and tries to show that the vast extent of these layers is evidence for a global flood.

His first example is the Tapeats Sandstone, which forms the base of the Paleozoic record in the Grand Canyon in Arizona. This formation is of Cambrian age, and sits unconformably above Precambrian sediments of the Grand Canyon Group. The main part of the Tapeats is composed of a very clean quartz sandstone. Almost all of the mineral grains in this sandstone are well-rounded quartz; there are very few grains with different composition, and there is very little clay in between the grains. This is typical of a well-worked sandy beach or eolian (wind-blown sand) environment.

Sandstones analogous to the Tapeats Sandstone form a continuous layer at the base of the Cambrian sediments in much of North America. In Montana this layer is known as the Flathead Sandstone, in Colorado it is the Sawatch Sandstone, in the Midwest it is the St. Simon Sandstone, and in New York it is the Potsdam Sandstone.

Snelling discusses the Tapeats Sandstone as follows:

The lowermost sedimentary layers in Grand Canyon are the Tapeats Sandstone, belonging to the Sauk Megasequence. It and its equivalents (those layers comprised of the same materials) cover much of the USA (Figure 3). We can hardly imagine what forces were necessary to deposit such a vast, continent- wide series of deposits. Yet at the base of this sequence are huge boulders (Figure 4) and sand beds deposited by storms (Figure 5). Both are evidence that massive forces deposited these sediment layers rapidly and violently right across the entire USA. Slow-and-gradual (present-day uniformitarian) processes cannot account for this evidence, but the global catastrophic Genesis Flood surely can.

Snelling actually understates the extent of these very similar basal Cambrian sandstones. Derek Ager, in his influential book The Nature of the Stratigraphical Record describes this as a feature of global, not just continental, proportions:

Even more remarkable than the basal Ordovician quartzite is the one that is found, almost all over the world, at the bottom of the Cambrian. […] Perhaps all that it is safe to say in this context is that very commonly around the world one finds an unfossiliferous quartzite conformably below fossiliferous Lower Cambrian and unconformably above a great variety of Precambrian rocks. This is true wherever one sees the base of the Cambrian in Britain, it is true in east Greenland, it is true in the Canadian Rockies and it is true in South Australia. In fact it is even more remarkable than this, in that it is not only the quartzite, but the whole deepening succession that tends to turn up almost everywhere; i.e. a basal conglomerate, followed by marine shales and thin limestones. In the northern Rockies one can even recognize at this level the “Pipe Rock’ of the Scottish Highlands–a bed full of borings known as Skolithos.

(Ager, The Nature of the Stratigraphical Record, 2nd edition, p.11).

[a few explanations: 1. For our purposes here, quartzite is a very-well cemented or slightly metamorphosed sandstone. 2. Skolithos is a trace fossil interpreted as worm borings or tubes]

The standard geological explanation of these Cambrian sandstones is that they were deposited in a shallow marine to intertidal environment. The Skolithos worm borings are consistent with this explanation, as are the variety of sedimentary structures (e.g. cross bedding) that are found in these units.

The Madison Limestone at Gates of the Mountains, Montana. The Madison Limestone is equivalent to the Redwall Limestone of the Grand Canyon. Credit: Richard I. Gibson

Snelling also uses the Redwall Limestone of the Grand Canyon as a example of a sedimentary rock unit that covers a very large area:

Another layer in Grand Canyon is the Lower Carboniferous (Mississippian) Redwall Limestone. This belongs to the Kaskaskia Megasequence of North America. So the same limestones appear in many places across North America, as far as Tennessee and Pennsylvania. These limestones also appear in the exact same position in the strata sequences, and they have the exact same fossils and other features in them.

Unfortunately, these limestones have been given different names in other locations because the geologists saw only what they were working on locally and didn’t realize that other geologists were studying essentially the same limestone beds in other places. Even more remarkable, the same Carboniferous limestone beds also appear thousands of miles east in England, containing the same fossils and other features.

Again, Snelling is understating the extent of these Mississippian Limestones. Similar limestones can be found not only throughout the American and Canadian West, but up to Alaska, into the Midwest, and in continental Europe and the Himalayas (Ager, pp. 7-8).

Snelling’s conclusion is that the only way to explain extensive layers like these is by invoking Noah’s Flood. He states that these layers could have only been deposited rapidly in a very short time. But there are a number of problems with Snelling’s explanation of these sediments:

    1. Snelling, like other young-Earth creationists, uses the wide extent of these units as evidence for large-scale, or even global-scale processes. I think that the opposite may be true: that the scale of these units works against the catastrophist explanation. For example, the fact that much of the North American continent (as well as large portions of other continents) is covered by the Cambrian Tapeats Sandstone and its equivalents means that all of the other Flood sediments—let’s say the rest of the Paleozoic and Mesozoic—had to already be in suspension in the waters above the pure-sand Tapeats:


  1. While all of these sediments were in suspension, according to the AiG/Snelling model, there could have been no mixing of sediments of different ages. There was no mixing of Ordovician with Silurian, or Paleozoic with Mesozoic.
  2. Likewise, there could have been no mixing of sediments from different sedimentary environments. Reef sediments (complete with intact ecological zonation: fore reef, back reef, breaker zone, etc.) couldn’t have mixed with beach sediments, deep water sediments couldn’t have mixed with intertidal sediments, and marine sediments couldn’t have mixed with non-marine sediments.
  3. Additionally, there could never have been any kind of turbulence that would place rock units out of order. The sequence isn’t Cambrian-Ordovician-Silurian-Devonian in one place, and Cambrian-Devonian-Silurian-Ordovician in another place.
  4. The boulder and cobble-bearing layers (conglomerates) of the Tapeats and its equivalents tend to be near what seem to be islands that stuck up above the sea, and the size of the grains decreases with increasing distance from the source areas. The rock types of the grains matches that of the islands. These are, therefore, local features; not the result of a global flood. The conglomerate layers likely originated during storms. (Additionally, the conglomerate layers don’t always occur at the base of the Cambrian sandstones as Snelling states).
  5. Snelling really gives no evidence in his article that these various units were deposited rapidly over large areas. He gives a few examples of rapid deposition on a smaller scale, such as the preservation of supposed water-laid dunes in the Coconino Sandstone (which most geologists interpret as wind deposits, not water deposits), but provides no evidence that catastrophism is the dominant means of deposition of any of the rock units he describes. Local deposition may be catastrophic for a short period of time, as in storm conglomerates, but it is a wild extrapolation to say that the entire geologic column was deposited rapidly, and there is plenty of evidence that it wasn’t.

The standard geological explanation of the Cambrian sandstones is that the sand was first blown around on the barren continental surface. This lead to exceptional rounding of the grains, distinctive microscopic textures on the sand grains, and a winnowing of virtually all clay. Eventually the sand was blown into shallow seas that covered large portions of the continents. Here the sand was reworked by various currents, as indicated by ripple and dune features (sedimentary structures) preserved in the sandstone. Actual deposition did not occur over the entire continent at once, but shifted as sea levels rose throughout the time of deposition. This explanation works well, is consistent with a variety of field and experimental data, and doesn’t require that all post-Tapeats sediments already be in suspension while the Tapeats and its equivalents were being deposited.

Remember: the Bible doesn’t say that the sedimentary rock record was laid down by Noah’s Flood. Organizations like Answers in Genesis do a considerable amount of arm waving and wild extrapolation in order to make the rocks fit their model, but this is completely unnecessary.

Up next: Flood Evidence #4: Sand Transported Cross Country.

With love for the body of Christ.

May 19, 2009 Posted by | Age of the Earth, Apologetics, Creation in the Bible, Geology, Origins, Young-Earth creationism | , , , , | 8 Comments