"[41]
[Footnote 41: "Der Bau der Schweizeralpen," p. 17.]
The favorite method of explaining these conditions has slightly changed
within recent years, as already remarked. For whereas the classic
example at Glarus was at first spoken of as a double fold-in from both
sides toward the Sernf Valley, this is now universally spoken of as a
"thrust fault," with the rocks all pushed one way. Incidentally it may
be noted that this very fact that what was long regarded as two
completely overturned folds is now spoken of as one flat-lying thrust
fault, is _prima facie_ evidence that there is here _no physical proof_
of any real overturning of the strata, such as we do find on a very
small scale in true folded rocks. The latter can usually be measured in
yards, feet, or inches; while in this example at Glarus the area
involved would be measured in many miles, and in some very similar
examples to be presently mentioned from America the measurement could
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_.
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