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

slow deposition.

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

thoroughly investigated.

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

Fossil Reefs?

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


Rapid Deposition

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

placid sea.


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

Bulletin, 43(1959):8.

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.