act which
can be clearly seen,--only we know not yet how to explain it in a
mechanical way."

An example in the Highlands of Scotland was about the next to be
discovered. Here, as Dana says, "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 he
further declares, "the thrust planes _look like planes of bedding, and
were long so considered._"[42]

Sir Archibald Geikie and others had at first described these beds as
naturally conformable; and when at length they were convinced that the
fossils would not permit this explanation, Geikie gives us some very
picturesque details as to how natural they look.

The thrust planes, he says, are with much difficulty 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 hilltop. 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."

Of a similar example in Ross Shire he declares:

"Had these sections been planned for the purpose of deception, they
could not have been more skilfully devised, ... and no one coming first
to the ground would suspect that what appears to be a normal
stratigraphical sequence is not really so."[43]

[Footnote 42: "Manual," pp. 111, 534.]

[Footnote 43: _Nature_, November 13, 1884, pp. 29-35.]

Here again we have unequivocal testimony from the most competent of
observers that there is _no physical evidence whatever_ to lead any one
to say that a ponderous scale of the earth's crust was really pushed up
on top of other portions, as this makeshift theory of "thrust faults"
involves. The _fossils are here in the wrong order_, just as in the case
at Glarus; that is all. The facts seem to be a flat contradiction to the
theory of definite successive ages, and to save the theory this
explanation of a "thrust fault" is invented, though there is absolutely
no physical evidence of any disturbance of the strata.

Our next stopping place is in the Southern Appalachian Mountains of
eastern Tennessee and northern Georgia. Here we have the Carboniferous
strata dipping gently to the southeast, like an ordinary low monocline,
_under_ Cambrian or Lower Silurian, one