OROGENY AND EARTH’S ROTATION 
73 
Each particular terrane in the vertical section possesses a stress- 
value of its own, which differs from every other one. Unequal 
crushing strength of the various layers, their different lenticular 
shapes, and their especial juxtaposition, soon produce complica¬ 
tions. The release of compressive strain is not always at the 
same slow and secularly uniform rate. Stress is locally cumula¬ 
tive; and release of it so often relatively sudden as to produce 
rupture in the rock-mass. Thus far the thrust appears to be also 
explainable on the theory of contraction due to a cooling globe. 
Found so inadequate in other respects the contractional hypothesis 
falls short in its application to horizontal rupturing of rock-masses. 
Viewing thrust-faulting as something more than local orographic 
effect it finds most satisfactory explanation in the larger telluric 
movements. By evaluating it in terms of cummulative stress on a 
prism of heterogeneous composition the necessary release com¬ 
ponent is found in the rate of retardation of the earth’s rotation. 
Geometrically it is expressed in the differential values of the 
earth’s geometrical radius and its variant radius of molar repose. 
The straticulate structures and the deformative conditions in 
nature are capable of very close, if not exact, reproduction in the 
arts. Modern newspaper rolls as they leave the mills display 
some especially instructive tectonic potentialities. Compared with 
the enormously thick Appalachian section of alternating limestones 
and shales the paper web itself is analogous to the rigid layers 
and the films between to the shale partings. The chief distinction 
between the phenomenon in nature and in the arts is that the paper 
is relatively tremendously tough, and hence cannot readily respond 
to rupture strains as do the rock layers. Without this relief the 
entire stress is converted into producing corrugated structures. 
The roll-paper is not tightly wound; but the winding process is 
done under a certain measurable tension which is retained to a 
very marked degree long after the roll is released from the 
mandril. This actual, or potential, stress is perhaps never entirely 
relieved until the roll is finally used on the printing press. 
Contrary to all expectation the unwinding of the paper-roll on 
the press, or its slower revolution in its wrapper on a spindle, 
does not uniformly relieve the original stresses. Because of slight 
local differences in the texture of the paper, unevenness in the 
thickness of the sheet, in the direction of revolution, or in the dry- 
