CHAPTER V

TURNED UPSIDE DOWN

How many of us have ever seen a mountain fall? Not very many. And yet events even more wonderful than this have frequently occurred in the past, as we are confidently assured by the leaders in geological science. Thus, in speaking of a certain region in the Alps, Dana[24] says that "one of the overthrust folds has put the beds upside down over an area of 450 square miles."

It is well worth our while to try to understand this statement. Our first and most natural inquiry is, What is it that leads scientists to think so? The details of this particular case are not very accessible, and so we are driven to reasoning from analogy from the known methods and constructions employed in this science. We must agree that none of the authorities who report this circumstance can testify as eye-witnesses of this marvellous event: they were not there on the spot when old Mother Earth turned this huge calcareous and silicious pancake. And yet there must be some kind of evidence by which these eminent men have arrived at this conclusion. What kind of evidence can it be?

We cannot imagine any physical evidence which could even remotely suggest such an idea. In fact from the universal custom of making the contained fossils the supreme test of the age of a rock deposit, we are perfectly safe in concluding that it is =solely because the fossils occur here in the reverse of the accepted order=, that we have this astounding picture of an immense mountain mass having been put "upside down over an area of 450 square miles." The "older" fossils are evidently here on top, while the "younger" ones are underneath, and of course some explanation must be given of this flat contradiction of the life succession theory.

But let us retrace our steps somewhat, and pick up the thread of our argument. We have already found quite serious reason to question the accuracy of this life succession theory: but there is still another way of testing its rationality. If certain fossils are not necessarily older than certain others, it might reasonably be expected that we would now and then find them reversed as to position, i.e., with the "younger" below and the "older" above. Accordingly we have the following very necessary caution from Prof. Nicholson:[25]

"It may even be said that in any case where there should appear to be a clear and decisive discordance between the physical and the palaeontological (fossil) evidence as to the age of a given series of beds, it is the former that is to be distrusted rather than the latter."

To meet all ordinary cases of this character, where the differences involve only a few formations representing a few "ages" or a few million years, the theory of pioneer "colonies" was invented by Barrande in 1852.

But for extreme cases, say where Silurian or Cambrian fossils occur =above= Jurassic, Cretaceous or Tertiary, there is in such a predicament always an anxious search made for faults and displacements; or gigantic "thrust-faults" or "overthrust folds," like the example already quoted from Dana, are described in picturesque language, many miles in extent--inventions which, as I have already suggested of a similar expedient to explain away evidence, deserve to rank with the famous "epicycles" of Ptolemy, and will do so some day.

Here is Geikie's highly instructive statement regarding the same conditions:--

"We may even demonstrate that in some mountainous ground, the strata have been turned completely upside down, _if_ we can show that the fossils in what are now the uppermost layers =ought properly= to lie underneath those in the beds below them."[26]

Some day, I fancy, a statement like this will be regarded as a literary curiosity.

There are plenty of examples under this head, though two or three ought to be as good as a dozen. In the part of Alberta east of the Rockies already referred to, is a section of country of about fourteen square miles at least--and we know not how much more--where Cambrian fossils are found =above= Cretaceous, and the inevitable "thrust fault" is thus described by one of the officers of the Canadian Geological Survey. He has just been speaking of "a series" of these "gigantic thrust faults":--

"One of the largest and most important of these occurs along the eastern base of the chain, and brings the Cambrian limestones of the Castle Mountain group over the Cretaceous of the foot hills. This fault has a vertical displacement of more than 15,000 feet (? three miles), and an estimated horizontal displacement of the Cambrian beds of about seven miles in an easterly section. The actually observed overlap amounts to nearly two miles. The angle of inclination of its plane to the horizon is =very low=, and in consequence of this its outcrop follows a very sinuous line along the base of the mountains, =and acts exactly like the line of contact of two nearly horizontal formations=.

"The best places for examining this fault are at the gaps of the Bow and of the south fork of the Ghost River. At the former place the Cretaceous shales form the floor of the bay which the Bow has cut in the eastern wall of the range, and rise to a considerable height in the surrounding slopes. Their line of contact with the massive gray limestones of the overlying Castle Mountain group is well seen near the entrance of the gap in the hills to the north. The fault plane here is nearly horizontal, and the two formations, viewed from the valley, =appear to succeed one another conformably=."[27]

But what an amazing condition of affairs is this. Here are great mountainous masses of rock, very similar in mechanical and mineral make-up to thousands of examples elsewhere. The line of bedding between them "acts exactly like the line of contact of two nearly horizontal formations," and in a natural section cut out by a river the two "appear to succeed one another conformably." And yet we are asked to believe that all this is merely an optical illusion. The rocks could not possibly have been deposited in this way, for the lower ones contain "Benton fossils" (Cretaceous), and the upper ones are Cambrian, and almost the whole geological series and untold millions of years occurred =after= the upper one, and =before= the lower one was formed. Solely on the strength of the infallibility of a theory invented a hundred years ago in a little corner of Western Europe, which "promulgated, as respecting the world, a scheme collected from that province," and assumed that over all the world the rocks must always follow the order there observed, we are here asked to deny the positive evidence of our senses =because= these rocks do not follow this accepted order. I must confess that I cannot see the force of such a method of reasoning. It is carrying the argument several degrees beyond the reasoning of the three little green peas in the little green pod, as narrated in the exquisite fable of Eugene Field. These wise little fellows noticed that their little world was all green, and they themselves green likewise, and they shrewdly concluded from this that the whole universe must also be green. But we are not told of their travelling abroad and persisting in a systematic attempt to explain all subsequently observed facts in terms of their theory.

This government Report last quoted from says that in the eastern part of Tennessee the Appalachian Chain "presents an almost identical structure," and refers to a similar state of things in the Highlands of Scotland. Dana, in the last edition of his "Manual" (p. 369), refers to this report, and reproduces some of its plates showing some of the structures referred to; and on another page, in speaking of this similar example in Scotland, says that "a mass of the oldest crystalline rocks, many miles in length from north to south, was thrust at least ten miles westward over younger rocks, part of the latter fossiliferous"; and further declares that "the thrust planes look like planes of bedding, and were long so considered."[28]

Geikie quite naturally devotes several pages in his "Text-Book" to a description of these conditions in the Highlands; but from one of his first reports on these observations, published in _Nature_[29] we get some much more suggestive details. The thrust-planes, he says, are difficult to be "distinguished from ordinary stratification planes, like which they have been plicated, faulted, and denuded. Here and there, as a result of denudation, a portion of one of them =appears capping a hill-top=. One almost refuses to believe that the little outlier on the summit does not lie normally on the rocks below it, but on a nearly horizontal fault by which it has been moved into its place."

Speaking of some similar conditions in Ross Shire, which he himself had previously described as naturally conformable, he declares:--

"=Had these sections been planned for the purpose of deception= they could not have been more skillfully devised ... and no one coming first to this ground would suspect that what appears to be a normal stratigraphical sequence is not really so."

"When a geologist finds" things in this condition, he says, "he may be excused if he begins to wonder =whether he himself is not really standing on his head=."

But I would only weary the reader by attempting to pursue this subject further. Those who wish to do so will find many additional examples in the larger works of Dana, LeConte, Prestwich, and Geikie, to say nothing of the more detailed statements buried in numerous Government Reports and special monographs in German and French.

From the very same set of beds different observers try to explain these puzzles in very different ways. Some, like Helm, will describe gigantic overthrust folds, and will draw immense arcs of circles several miles high in the air, as the place where the rocks must once have been. Others, like Rothpletz, from an examination of the very same rocks, will cut the mountain up into sections with imaginary fault-planes, and will tell how, in the district about Glarus for example, an enormous mass of mountains "travelled from east to west a distance of about twenty-five miles from the Rhine valley to the Linth," or how the "Rhatikon Mountain mass travelled from Montafon valley to the Rhine valley, about nineteen miles from east to west."[30]

With regard to some at least of these conditions in the Alps, Geikie virtually admits that these incredible and self-contradictory earth-movements are necessitated by and described from fossil evidence only, for he says:--

"... the strata could scarcely be supposed to have been really inverted, save for the evidence (_sic_) as to their true order of succession supplied by their included fossils." "... portions of Carboniferous strata appear as if regularly interbedded among Jurassic rocks, and indeed could not be separated save after a study of their enclosed organic remains."[31]

In fact, we are perfectly safe in concluding in all similar cases that we may encounter in the literature of the science that it is the reversed order of the fossils which constitutes the whole evidence; for, as I have said, we can imagine no possible physical evidence competent to form a foundation for such ideas, nor do I know of anything save the exigencies of this venerable theory of life succession, for which otherwise competent observers will thus freely sacrifice their common sense. When the dividing line between two sets of strata "acts exactly like the line of contact between two nearly horizontal formations," so much so that in a natural section cut out by a river the two "appear to succeed one another conformably," a calm judicial mind, divested of all theoretical prejudice, instead of talking about these conditions having been planned by nature "for the purpose of deception," will find no difficulty at all in believing that these rocks were really laid down in the =reverse order= in which we now find them, with the "younger" below and the "older" above, and only one under the hypnotic spell of a preconceived theory would at the suggestion of such a fact begin "to wonder whether he himself is not really standing on his head."

FOOTNOTES:

[24] "Manual," p. 367.

[25] "Ancient Life-History of the Earth," p. 40.

[26] "Text-Book," p. 837, Ed. of 1903.

[27] "Annual Report," New Series, Vol. II., Part D, pp. 33-34.

[28] pp. 111, 534.

[29] Nov. 13, 1884, pp. 29-35.

[30] See _Nature_, Jan. 24, 1901, p. 294.

[31] "Text-Book," p. 678.