OROGENY AND EARTH’S ROTATION 
51 
f 
OROGENIC CONSEQUENCE OF A DIMINISHING 
RATE OF £\RTH’S ROTATION ^ 
By Charles Keyes 
Recent curious experiments in geotectonics appear to indicate 
in no mistakable terms that the larger relief features of our globe 
are not really the complex dynamical phenomena which they are 
commonly supposed to be, but that genetically all are merely some¬ 
what different expressions of the same simple tangential stresses. 
To this horizontally directed power, acting steadily, uniformly, 
eternally, seem ascribable both those grander surface effects such 
as the great oceanic depressions and the continental protuberances 
with their sharply elevated borders and their low, sea-level inter¬ 
iors, and those relief features of the second order which arise 
from orographic wrinkling, overthrust, intrusion of magmatic 
lavas, and volcanic activities. 
None of these phenomena now suggest that they are necessarily 
a direct outcome of contraction of the earth’s nucleus; for most 
evidences of crustal compression due to actual shrinkage prove to 
be only apparent rather than real. Vertical up-floating of orogra¬ 
phic prisms of the earth’s shell are perhaps possible and even prob¬ 
able, but not in a strictly isostatic sense in which they are fre¬ 
quently regarded. In their origin all of the phenomena enumer¬ 
ated point to their being a direct and necessary consequence of 
strains imposed upon an unequally rigid crust through mass- 
movement induced by secular retardation of the earth’s revolution. 
As such they are capable of exact numerical evaluation, and are 
reducible to formal mathematical equation. Their graphic ex¬ 
pression is the straightening and shortening of the curved radius 
of molar repose. In any rotating body the shortening of this 
1 Paper presented in outline before the Geological Society of America at the Bal¬ 
timore meeting. 
