best be made in degrees of latitude and longitude or in arcs of the
earth's circumference. In these larger examples it is manifestly
impossible that there should be any physical evidence sufficient to
indicate a huge earth movement of this character, especially when, as is
usually the case, both the upper and the lower strata are _quite
uninjured in appearance_. No; the fossils are here in the wrong order,
that is all. And so, to save the long established doctrines of a very
definite order of successive life-forms, this theory of a "thrust fault"
is offered as the best available explanation. As Dr. Albert Heim himself
once expressed it very naively in a letter to the present writer, that
the strata over these large areas are in a position manifestly at direct
disagreement with the received order of the fossils, "is a fact 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