Science in Christian Perspective

Stratigraphy and Paleontology
CORDELIA ERDMAN
Instructor in Geology, Wheaton College
Wheaton, Illinois

From: JASA 5 (March 1953): 3-6, 11.   Responses by:  Mr. S. C. Sinclair Dr. Wm. Tinkle Dr. J. L. Kulp

The early days of geologic investigation belong to the latter half of the 18th century. At that time nobody was paying much attention to fossils, and rocks were classified on the basis of their gross characteristics. The great controversy of the day was between the Neptunists, who believed that a receding, once world-wide ocean was responsible for forming all rocks, and the Plutonists, who maintained that many rocks had cooled from a molten state. Hutton, champion for the Plutonist school, also contended that in the case of those rocks which were composed of sediments, older beds were covered by successively younger beds. This seemingly very obvious principle is basic to all subsequent stratigraphic reasoning. It is known as the Law of Superposition.

It was not long before a second law of stratigraphy became apparent. A young English surveyor's assistant (William Smith) in 1796 began collecting fossils from the rock layers he traversed in England and Wales. As he studied these, he discovered that each layer contained its own distinctive fossils. One day when he was calling upon a cleric of the Church of England, he picked out unlabeled fossils from the man's collection and told him the locality from which they had come. The amazed churchman was quick to see that Smith had stumbled on something important, and he encouraged him to study further. As a result, there was published in 1815 the first geologic map of England; and, with even more far-reaching effects, the principle of Faunal Dissimilarity was set forth, the principle that each rock unit in a given series contains a fauna distinguishable from all others in the series.

George Cuvier, the great anatomist and paleontologist, carried on Smith's idea. He, too, recognized that each major rock unit carried a distinctive fossil assemblage. Since he believed in the fixity of species, a dogma which says that every species is a separate and direct creation, he could only explain sudden appearance of new forms in successive layers on the basis of local catastrophes followed by immigration of life from distant places. Alcide d'Orbigny continued to uphold this catastrophism as the explanation for fauna] dissimilarity, but he postulated re-creations in place of immigration. Deperet, according to R. S. Lull (1947, p. 6), quotes his statement of 1848:

. . . twenty-seven times in succession, distinct creations have come to re-people the whole earth with its plants and animals after each of the geological disturbances which destroyed everything in living nature. Such is the fact, certain but incomprehensible, which we confine ourselves to stating, without endeavoring to solve the superhuman mystery which envelops it.

Meanwhile, without worrying about any "superhuman mystery," Charles Lyell was busily investigating the rocks around Paris. He adopted and adapted Smith's rock units, arranged in order of superposition, and in 1833 he presented to the geologic world a stratigraphic column which was really the first geological timetable. As his groups or systems of rocks became identified over more extensive areas of the continent, it became increasingly evident that the principle of faunal dissimilarity was indeed a law of nature. The Catastrophist philosophy thus had reason to become more firmly entrenched. It was supported by the accumulating evidence that rock systems were separated by erosion surfaces or at least by lithologic discontinuities which indicated a fairly rapid change in the environment. Since these were synchronous with gaps in the fossil record, that is, the types of life fossilized above and below the discontinuity did not grade into one another, the belief developed that they represented "recognizable and universal dates on the geologic calendar" (Krumbein and Sloss, 1951, p. 15).

Now all of this was done before the publication of Darwin's "Origin of the Species" (1859), and although Lamarck had advanced evolutionary ideas previously, these had haddittle influence on the early stratigraphers. This means that the geologic timetable was based on objective fact alone and was not formulated to support evolutid.nary concepts, nor was it even an outgrowth of evolutionary concepts.

However, the modern period of paleontology and stratigraphy did begin with Charles Darwin, because, as Neaverson states (1928, p. 4):

In the light of evolutionary theories, the gradual increase in complexity of organization as shown by fossils passing from earlier As later rocks assumed new significance and the mutual inter dependence of paleontology and stratigraphy was more emphasized.

In other words, the scientists threw over catastrophism altogether and accepted evolution as an alternative for a phenomenon which was already well established. According to the new theory, successive fossil faunas represented not re-creations but groups which would merge into one another in a time direction except for the interruptions in the sedimentary record.

Determining equivalent age.-The Christian world has long raised its eyebrows at geology. Many times one hears doubt expressed concerning the validity of the geologic timetable or concerning the validity of using fossil content to determine equivalent age of rock units. Much of this doubt grows out of a confused belief that all ideas of organic development are inherently contrary to special creation; and out of the erroneous assertion that "geologists date the fossils by the rocks and then turn around and date the rocks by the fossils." Both of these concepts have been vigorously propagated in much pseudo-scientific Christian" literature.

We have seen that the geologic timetable is based upon the two principles of stratigraphy: 1. in a normal sequence of rock layers, the oldest must be on the bottom and the youngest at the top; 2. rock units contain their own distinctive fossil assemblages. The problem is to know how to equate or compare the ages of layers occurring in geographically separated sequences: in other words, how to fit rock strata into an over-all chronology.

Many times the stratigrapher is able to compare data from two areas which are not widely separated; or he can actually trace layers from place to place: thus he can establish their time equivalence on nonpaleontologic grounds. In other cases such tracing is impossible. Then the stratigrapher depends upon similar fossil assemblages alone to make his correlation.

In comparing the rocks of two separated districts the geologist has to rely entirely on the fossils present in those rocks. Supposing the fossil assemblages to be identical, the rocks are held to be contemporaneous (or synchronous), even if they occur in such widely separated countries as England and America. (Neaverson, 1928, p. 7.)

The reasoning is this: similar fossil assemblages could only occur at approximately the same time in geologic history: therefore, rocks containing such similar assemblages must be approximately equivalent in age. The next question is, is this valid reasoning?

First of all, note that a consistent relative order of appearance of varying organisms is demonstrated in every area where the Law of Superposition can be applied. Dunbar writes:

Where the structure of the rocks is simple, the succession of faunas that occupied the region from age to age can be determined by studying the fossils of successive formations. When this succession has been confirmed by wide experience in many regions of undisturbed strata, we may be confident that different forms of life succeeded one another in this order in time on the Earth . . . The relative time of existence of a vast number of kinds of animals and plants has now been established. and their place in the geologic column has been confirmed by the cooperation of geologists the world over. This is not a theory derived a priori, but a discovery painfully and tediously worked out by the systematic study of the faunas of rock formations first carefully located in the geologic column. (Dunbar, 1949, p. 8,) (Last italics mine.)

And again: "The appearance of trilobites and dinosaurs and three-toed horses is not fortuitous and irregular" (Dunbar, 1949, p. 8). However, the fact that we can establish relative ages for the various kinds of organisms in one location, plus the fact that these same relative ages hold good in other regions, too, does not necessarily guarantee equivalent age of like kinds. Paleontologic correlation rests upon this issue, "Does any characteristic occur only once in time, or may it be repeated at successive intervals?" If a characteristic type of assemblage does occur only once, then assemblages of this type must be time equivalents. There seem to be several possible explanations for the appearance of similar fossil faunas and floras in divergent regions.

1) One may revert to catastrophism and regard the organic assemblage of each layer as a special creation of God. If there was an extensive series of worldwide catastrophes (a view not substantiated by geology), then the creation of organisms which ensued was probably (but not necessarily) a creation of like forms with world-wide distribution. This would make them of exactly the same age. If one postulates only local catastrophes, then he must say that God always re-created organisms in the same sequence (first trilobites . . . later ammonites . . . then reptiles, etc.). This would invalidate the age of equivalence of layers containing like forms.

2) One may believe that all species existed from the beginning and that recurring fossil groups merely indicate the recurrence of certain environmental conditions. In this case, fossil sequences must be due to progressive changes in environment which caused immigration of life from other areas. This, too, would invalidate age equivalence.'

3) The evolutionist says that "Different kinds of animals and plants have succeeded one another in time because life has continuously evolved; and inasmuch as organic evolution is world wide in its operation, only rocks formed during the same age could bear identical faunas" (Dunbar, 1949, p. 8).

4) One may believe that different kinds of animals and plants have succeeded one another in time because God created the great categories of organisms at successive points in time, giving to each the ability to be changed and developed within God-ordained limits. Then like assemblages represent a cross-section of time, and the degree of equivalence depends upon the rapidity of dispersal of the changing forms.

There is little in the way of geologic evidence to give credence to the grosser forms of Catastrophism. "There is no longer much general support among stratigraphers for the principle of correlation based on synchronous diastrophism" (Krumbein and Sloss, 1951, p. 308). If local catastrophes are involved (and there are many of these recorded in the rocks) there would be no need for re-creation, for the population would be reinstated by immigration. But if fossil sequences are always and only a record of successive immigration of forms which all existed from the beginning, there remains to be explained the amazing coincidence that they have always immigrated in exactly the same chronological order (considering life as a whole) or that they have immigrated in such a fashion as to build spurious sequences (considering directional change manifested within a genus or family). Also one might ask where was the source area from which all these animals came. Therefore we are left with alternatives 3) and Q: thorough-going evolution or modifiction within successively created categories. In either of these cases, closely similar faunas represent generally equivalent segments of time.

Index Fossils.-The Law of Faunal Dissimilarity deals with faunal assemblages. It is by means of such groupings of species that the "finer resolution of time-rock distinctions may be accomplished," for, as Krumbein and Sloss continue (1951, p. 306),

Of course the most sweeping criticism is that the idea of increase in complexity of life with increase of elevation is only superficially tenable.

If the approximate biozone (historical span) of a number of component species in an assemblage are known, although each biozone may be relatively long, it is probable that only in a short timerock interval can all the species be expected in the same assemblage.

For grosser distinctions recourse is had to index fossils, those forms which have a very wide geographic distribution but to have everywhere a narrow time range. Krumbein and Sloss point out (1951, p. 305): 

Time-rock correlation by index fossils would be much more confidently applied if there were many truly cosmopolitan species . . . (but) the experienced stratigraphic paleontologist can usually place the strata involved in their proper system with some assurance. At least, the fauna can be placed as either high in one system or low in the succeeding one. Since the biozones of most species persist through several ages and commonly through more than a single epoch, application of individual species to correlation of specific stages or series is rarely effective.

Dunbar, writing for the beginning student in geology, also emphasizes the possibility of determining relative age by use of index fossils:

During the last one hundred years, paleontologists in many parts of the world have cooperated in gathering such a mass of information that it is now as easy for a trained specialist to identify the relative . . . age of a fossiliferous rock formation as it is to determine the relative place of a sheet in a manuscript by its pagination. (Dunbar, 1949, p. 52).

The concept of index fossils is used extensively. However, the paleontologists would be the first to admit that in some cases hasty application may have led to invalid conclusions. Constant rechecking and revision eventually point up such inconsistencies.

Perhaps now we are in a position to examine -the charge that geologists are guilty of circular reasoning. Their actual procedure is: 1) to observe the chronological sequence of rock units in a given area, and 2) from this to determine the chronological sequence of the contained fossils. (This is "dating the fossils by the rocks"). 'Men the fossils of another area may be compared to this standard sequence and assigned a relative geologic age by applying the concept of time equivalence for index fossils or like assemblages. This is not circular reasoning. It is a piecing together of information with reference to a standard.

Present status of paleontologic correlation.-How much reliance does the stratigrapher place on this fossil evidence in his effort to determine the age equivalence (or non-equivalence) or rock units? There are actually many means of correlation other than the paleontologic one. Krumbein- and Sloss explain that (1951, p. 288) 

Normally, two or more methods are employed in the solution of any individual correlation problem and no generalization can be made as to which methods are most useful in any individual case. 'Some of the methods that may be used are: 1) tracing layers laterally; 2) lithologic identity; 3) relative position in sequence; 4) structual relationships. These methods are useful only in relatively local situations.

However, Lull describes the process of correlation thus (1931, p. 19):

Having settled the sequence of strata in a given region, fossils are sought for, especially such genera and species as are sufficiently distinctive to be considered "horizon markers." Once determined, these serve to identify the age and, therefore, correlate the rocks containing them wherever they may be found.

It was once suggested that faunal migration is such a slow process that by the time a fauna reached the opposite quarter of the globe its original centre of dispersal would be occupied by a very different faunal development . . . Later it was realized that the time needed for migration is negligible compared with the period taken by the deposition of a rock series, so that essentially similar faunas are nowadays held to be contemporaneous . , .

Stratigraphic paleontologists recognize the limitations of their practice. James Gilully, past President of the Geological Society of America, in 1949 made an honest admission which sums up the situation. He said:

If several species that arose In different centers come to live in a particular area their order of superposition may be different in different parts of the area . . . When we take into account the entire fauna we never find such reversals, but the fauna as a, whole does not, of course, change so quickly as the individual species. Even in theory it will never be possible to be certain of the precise equivalence of, beds in widely separated . regions.. Paleontology . . . can never offer us a chronology capable of indefinite refinement.

It would be safe to say, that Gilully's comments reflect a growing concern within: the ranks of geolo. gists themselves. The current 'use of paleontology' in stratigraphy has been undergoing some rather telling analysis and criticism in the past few years. Witness this excerpt from a paper entitled "Geological Correlation and Paleoecology" by Robin S. Allan (Allan, 1948):

Because of the sterility, of its concepts, historical geology, which includes paleontology and stratigraphy, has become static and unproductive. Current methods of delimiting intervals of time, which are the fundamental units of historical geology, and of establishing chronology are of dubious validity. Worse than that, the criteria of correlation-the attempt to equate in time, or synchronize, the geological history of one area with that of another-are logically vulnerable. The findings of historical geology are suspect because the principles upon which they are based are either inadequate, in which case they should be reformulated, or false, in which cAse they should be discarded. Most of us refuse to discard or to reformulate, and the result is the present deplorable state of our discipline.

This undoubtedly represents an extreme position; but Allan's plea for more use of principles of sedimentation and of paleoecology in interpreting and correlating rocks is a plea which finds an echo in many other geological writings. Raymond C. Moore, writing in the same year as Dr. Allan, stated firmly that assemblages of fossils could be used as indicators of geologic time only if subsequent and antecedent assemblages were known from the same area. He writes further (Moore, 1948):

Possibly excepting correlations based on occurrence of shortlived free-floating or swimming organisms of the sea, such as graptolites and some cephalopods, or rapidly migrating land animals and plants, most intercontinental correlations of fossil species or assemblages cannot be accepted as indicating precise contemporaneity.

However, these objections pertain to refinements within the timetable. As noted earlier in this paper, geologists have reason to be satisfied concernmig the over-all sequence in which organic forms have made their appearance. But when it comes to deciding what life forms were characteristic of the smaller time units, there is far less satisfaction. The smaller the time unit, the more difficult the problem. Nevertheless, modern research in sedimentation and paleoecology will doubtless point the way toward more reliable and effective use of paleontologic methods of stratigraphic correlation.

Dunbar, Carl 0. 1949. Historical Geology. New York, John Wiley & Sons, Inc.
Gilully, James. Presidential Address, Bulletin of the Geological Society of America, Vo. 60, No. 4, 1949.
Krurabein, W. C. and L. L. Sloss. 1951. Stratigraphy and Sedimentatiom San Francisco, The W. H. Freeman & Co.
Lull, Richard S. 1931. Fossils. New York, The University Society, Inc.
1947. Organic Evolution. New York, The Macimilan Company.
Moore, Raymond C. Stratigraphical Paleontology. Bull. G.S.A., vol. V9, 1948 (April).
Neaverson, Ernest. 1929. Stilatigraphical Paleontology. London, Macmillan & Co., Ltd.

Discussion

Mr. S. C. Sinclair: Many of you folk may be wondering why the A.S.A. is divided on the extent of mutational changes. One group believes that a sequence such as the modern horse from Eohippus is possible while the other group denies that any such change could occur. The answer to this difference lies in the perspective of the two groups. One group is looking at it Paleontologically, the other group Genetically.

Fossil sequences such as the horse fit beautifully into an evolutionary trend if such a thing can be shown to exist, but circumstantial evidence of this sort can not prove the theory in the absence of more direct evidence,, such as has not been found in Genetics. Really the sort of Evolution one believes in, whether organic, theistic or threshold is decided by where one leaves God for chance. Variety from heterozygosity is not Evolution.

A certain taxonomist I know, though he knew the disfavor of Lamarckism yet was so impressed with the ingenious manner in which animals are adapted to the environmental niche they fill, could not help but feel that some mechanism for specifically adapting them to their environment must exist. I agree with him that adaptations do not look like haphazard mutations but show the hand of almighty God; and I believe the Bible bears me out that basic species patterns are the design of God. Job 39:13-17, 5-6 and 40;15,19.

I believe I have in my mind about what I would consider a hybrid difference between two individuals and a species difference. Dr. Larnmerts feels he can classify plants on this basis, and that, confusion as to what is or is not a species difference is merely lack of experience. Hybrid differences usually involve the presence or absence of single genes, whereas species differences typically involve a different gene pattern as well as one or more different genes. Though most of the genes are shared in common, their integration in -a successful individual in a given environment constitutes their uniqueness. For example the aquatic spider differs in several essential ways from a similar terrestrial spider. 'Me water repellent hairs that hold the bubble of air over its abdomen must be of the right rigidity, of just the right number per square inch, growing on just the right part of the body, and of the right shape with a hook on the tip of just the right size and angle. The more complicated things such as instinctand physiological fitness must also be right.

If changes such as bunodont teeth and hind feet bearing three hooved toes to hypsodont teeth and monodactyls are possible, then changes such as a low receding forehead to a high sharp one, heavy protruding jaw to a flat vertical one, fang-like interlocking canines to even dentition, and stooped posture to an erect one are theoretically possible, fossil sequence or no fossil sequence. If changes such as these can be definitely proved then we must look further than genetics for a mechanism. Why not let us admit that God is responsible for these changes, if such can be proved, and if it's God, it's not Evolution. The lack of a fossil sequence is a pretty flimsy defense for the faith of God's precious ones. And why quote Simpson as an authority when Evolution is his alternative to faith in the God of Creation?

I don't believe we fully appreciate the effect this theory has had, not alone on biology students but on philosophy and theology and practically every area of human thought. The apostle Paul said that if meat cause my brother to stumble then I will eat no meat. So may we say that if My Evolution cause my brother to stumble then I will have nothing to do with this philosophy of chance.

An area needing further study is the distribution of organisms in time (geologically) and space (geographically). Could it be possible that a pattern of plant and animal life was established in one or several areas and subsequently spread in all directions considering ecological barriers? If so a lag in distribution might cause apparent sequences in the earth's strata. Another factor, mentioned by Dr. Kulp, A.S.A. Journal, 1-3, 23 (1949), is that necessary for soil preparation for forest growth. Certain characteristic changes in plant life would occur beginning with bramble bushes, possibly, on up to the evergreens that require shelter for proper rooting. With these floral changes would go the animal changes characteristic of them. These changes might also look like geologic sequences.

Dr. Wm. Tinkle: I wish to say that this paper by Miss Erdman is a fair statement of the position of the standard geologist. However, the standard geologist is an evolutionist. I appreciate this paper very much for there is a great deal of truth in it; however, in some respects I must be very critical. 

Regarding index fossils, in order for a certain species of fossil to be a good index, somebody must tell us when that species started (created or evolved) and also when it became extinct, at least in relation to other species and preferably in relation to time. Suppose that we take a special species of trilobite as an index for a certain formation. Then a new forma tion of rocks is searched out and we flnd that species of trilobite there. What is the conclusion? The new formation is the same age as the old since they have the same fossils. Are there not also two other possibili ties ? Perhaps this species of trilobite could have lived earlier or later than previously indicated. There is still another choice. This species of trilobite may have lived in a wider region than we had formerly thought. Again, is the geologist omniscient? What about early geologists? Smith was not educated. Lyle was educated but in law. Sedgwick was trained in Latin and Greek.

Dr. J. L. Kulp: I don't believe we would expect the early geologists to have had training since it was not possible to obtain such training. But no present geolo gist accepts the index fossils because anyone else says so. The rocks are still there. You can still find the same sets of fossils and since the early work of the men you have mentioned, thousands of trained men have gone across the face of the earth wherever the stratigraphic section outcrops appear and have found sequences wherever the outcrop is not deformed. And I should add that only about one per cent is deformed and there is always considerable evidence of it.

Taking the total fossil picture the broad outline of life is clear and undebatable and this is exactly the sequence which is described in Scripture. This makes it distinct from any other early cosmology.