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HAYFORD. 
of that particular matter — that is, by increase or decrease in 
volume of given masses. In either of these cases, or in any 
combination of them, there is permanent deformation of 
the material, a yielding to applied stresses, and we are led 
again to the idea that the earth is a failing structure. 
If the earth is now and has long been a failing structure, 
the material accessible at its surface should bear the evidence 
of that fact in recognizable form, just as the twisted mass 
of steel on the bank of the St. Lawrence bears in itself easily 
recognizable evidence that a bridge has failed near Quebec. 
The material composing the earth’s surface does bear the 
evidence, and the evidence has been described by thousands 
of men. If one consults the literature of geology, and 
especially that portion of it which sets forth directly the 
facts which have been observed, rather than the generaliza- 
tions from them, he finds everywhere descriptions of fault- 
ing, of warping of strata, of folding of strata, of overthrusts, 
of intrusions, of vulcanism, of uplift, of subsidence. All 
these are evidence of past failure, of permanent non-elastic 
yielding to applied stresses. The only parts of the earth’s 
outer crust where such evidence has not been found are ap- 
parently the parts of the land surface in which there has 
been little or no geological exploration and the ocean bottom, 
where the evidence would be extremely difficult to detect. 
Moreover, the geologic evidence shows that these yieldings 
have occurred at various epochs throughout the whole in- 
terval of time covered by the geologic record written in the 
rocks, and that the yielding, at least in some cases, has been 
gradual rather than sudden. In whatever area on any con- 
tinent a geologist works he finds this evidence, and, so far 
as I am able to judge, it appears that the more a given area 
is studied, the more conclusive is the evidence that per- 
manent deformation under stress has there taken place. 
Just as the geologist who studies cubic miles of the earth 
finds abundant evidence of past failure, so also does the 
geologist who studies cubic millimeters of rock under the 
microscope find similar evidence in the structure of the rock. 
