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.