No. 210 WERE GRAND CANYON LIMESTONES DEPOSITED BY
CALM AND PLACID SEAS?
by Steven A. Austin, Ph.D.*
Lime Mud Deposits?
Shallow-water lime muds in today's tropical oceans accumulate at a
rate of one foot thickness per one thousand years. These muds are
formed by mechanical breakdown of carbonate-containing sea
creatures. Modern muds are believed by evolutionists to provide
an excellent example of how ancient lime mudstones ("micritic
limestones") were accumulated in Grand Canyon. Even some
creationists believe that the evidence from lime muds is so
convincing that one must certainly believe in long ages of slow
deposition for Grand Canyon limestones. Dan Wonderly, for
example, insists that all one has to do is compare the modern lime
muds with the texture of the Redwell Limestone of Grand Canyon to
be convinced that the Canyon strata require millions of years to
be deposited.' Wonderly claims that young-earth creationists, in a
very deliberate way, ignore or neglect these data, which prove
There are strong dissimilarities, however. Modern
shallow-water lime muds are dominated by silt-sized crystals
(approximately 20 microns in diameter) of the mineral aragonite
(most contain 60-95% aragonite, and 0 to 10% calcite) derived from
disaggregation or abrasion of skeletons of marine organisms.2
Ancient lime mudstones ("micritic limestones") are abundant in
Grand Canyon, and are dominated by clay-sized crystals (less than
4 microns in diameter) of the mineral calcite (nearly 100%
calcite and/or dolomite) with sand-size and larger skeletal (sheu)
fragments floating in the fine crystal matrix.3
Geologists emphasize the textural, mineralogical, and
chemical differences between modern lime muds and many ancient
Micritic limestones, composed essentially of calcite, have
textures quite different from those of the aragonite-dominated modern
lime muds that long had been regarded as their precursors.4 and
Modern carbonate sediments contrast sharply in their
chemistry and mineralogy with ancient carbonate rocks.5
Even the shapes of the grains are strongly discordant between the
modern and ancient lime muds:
Furthermore, the grain (crystal) size distribution and grain
(crystal) shape characteristics of modern lime-mud sediment
are very different from their lithified counterparts.6
Could some process of recrystallization have been responsible for
transforming these modern coarser-textured aragonite muds into the
finer-textured calcite muds which compose limestones? This is a
muchdisputed question. The process of recrystallization, it has
been recognized, makes larger crystals from small crystals, not
smaller crystals from larger ones. How could such a process form
the dominantly finegrained muds which now compose limestones?
Early workers on the microcrystalline calcite ("micrite") ooze of
ancient limestone argued that it formed by direct precipitation
from sea water,7 not from recrystallization or even extensive
abrasion of skeletons of marine organisms. This process, believed
to form ancient lime muds, is much different from slow processes
in modern oceans. The "lime-mud problem" has become more
apparent in recent years, as the compositions and textures of
modern lime muds and fine-grained limestones have been more
At the present time, it would be inappropriate to suppose that the
scientific evidence requires that ancient fine-grained limestones
were derived from lime muds resembling the muds being deposited
slowly in modern tropical seas. Evolutionists may make the
assumption, but the facts do not justify it. In the words of F.J.
Pettijohn, "The origin of micrite is far from clear."8
An important problem to be faced by the Bible-believing geologists
is the existence of alleged limestone "reefs."9 Critics of the
Flood theory say that many abundantly fossiliferous limestones are
organically constructed "reefs," which were accumulated slowly
along the edge of an ancient sea. The Flood, some critics say,
could not have deposited such structures, because it took
thousands of years to construct a huge waveresistant framework, as
innumerable generations of organisms chemically cemented
themselves, one on top of the other. If Grand Canyon limestones
were accumulated slowly in tranquil seas, we might expect to have
large, organically bound structures ("reefs") buried with the lime
mud. Do large, organically-bound structures occur within Grand
Canyon limestones? Can these be proven to represent in situ,
slowly accumulated sea floor?
The most extensive study of Grand Canyon limestone was by McKee
and Gutschick. They admit, "Coral reefs are not known from the
Redwall Limestone."10 Concerning laminated algal structures
(stromatolites) which might form slowly in tidal flat
environments, they say, "the general scarcity or near absence of
bottom-building stromatolites suggests that places generally above
low tide are not well represented."" The cautious statements
concerning algal structures in Redwall Limestone were used by Dan
Wonderly to argue against the Flood. He uses these statements to
imply that some of the algal structures indeed represent in situ
ocean floor.12 A careful study of McKee and Gutschick's work shows
that the laminated algal structures typically show concentric
structure (oncolites), and are best interpreted as algal masses
which have been transported by rolling. These authors belieue
that the Redwall Limestone represents in situ ocean floor
deposits, but they have not proven their case with empirical
Evidence of rapid deposition and burial of fossils is found
in the Redwall Limestone. Along the Colorado River at Nautiloid
Canyon, just north of Grand Canyon, the Redwall Limestone contains
large fossils of nautiloids -squid-like marine animals that
possessed a straight shell, sometimes over two feet long. The
long, slender shells of numerous nautiloids, in Nautiloid Canyon,
have a dominant orientation, indicating that current was
operating, as fine-grained lime mud accumulated.9
Not all limestones of Grand Canyon are fine-grained. Some
contain coarse, broken fossil debris, which appears to have been
sorted by strong currents. The Redwall Limestone contains coarse,
circular disks (columnals) from the stems of crinoids-marine
animals which lived in a cup, or head,
attached to the stem. Evidently, water currents winnowed the
finer sediment away, leaving a "hash" of crinoid debris.
Occasionally, the heads of crinoids are found embedded in the
coarse, circular disks. Sometimes these occur in deposits of
inclined bedding (cross beds), which imply strong currents.
Because modern crinoid heads in today's ocean are susceptible to
rapid breakdown when these organisms die,'O we conclude that rapid
burial is needed to produce fossil crinoid heads.
Evidence of current transport of lime sediment is provided by
quartz sand grains, which are found embedded in the fine-grained
matrix of many limestones. These quartz sand grains are common in
the Kaibab Limestone of Grand Canyon. They are even known in the
Redwall Limestone. Because the quartz sand grains cannot be
precipitated from sea water, they must have been transported from
some other location. Any water current fast enough to move sand
grains would be able to move lime mud, as well. These quartz sand
grains argue that the Kaibab Limestone was accumulated from
sediment which had been transported by moving water, not simply
deposited from a slow, steady rain of carbonate mud in a calm and
1. D.E. Wonderly, God's Time-Records in Ancient Sediments
(Flint, Michigan, Crystal Press, 1977), pp. 138-140.
2. R.P. Steinen, "On the Diagenesis of Lime Mud: Scanning
Electron Microscopic Observations of Subsurface Material from
Barbadox, W.I.," Journal of Sedimentary Petrology
3. E.D. McKee and R.G. Gutschick, History of the Redwall
Limestone in Northern Arizona (Boulder, Colorado, Geological
Society of America, Memoir 114, 1969), p. 103.
4. Z. Lasemi and P.A. Sandberg, "Transformation of
Aragorite-dominated Lime Muds to Microcrystalline
Limestones," Geology 12(1984):420.
5. R.M. Garrers and F.T. Mackenzie, Euolution of Sedimentary
Rocks (New York, W.W. Norton, 1971), p. 215.
6. Steinen, op. cit. p. 1139.
7. R.L. Folk, "Practical Petrographic Classification of
Limestones," American Association of Petroleum Geologists
8. F.J. Pettijohn, Sedimentary Rocks (New York, Harper & Row,
3rd ed., 1975), p. 334.
9. S.E. Nevins, "Is the Capitan Limestone a Fossil Reef?"
Creation Research Society Quarterly, 8(1972):231-248.
10. McKee and Gutschck, op. cit., p. 557.
11. Ibid, p. 546.
12. D.E. Wonderly, Neglect of Geologic Data: Sedimentary Strata
Compared with YoungEarth Creationist Writings (Hatfield,
Pennsylvania, Interdisciplinary Biblical Research Institute,
1987), p. 17.
13. Observation of Steven A. Ausfin in Nautiloid Canyon, April
14. D.L. Meyer and K.B. Meyer, "Biostratinomy of Recent Crinoids
(Echinodermata) at Lizard Island, Great Barrier Reef,
Australia," Palaios 1(1986):294-302.