DYNAMICAL GEOLOGY 
81 
position more than two miles beneath the surface of the ocean. 
Despite the removal of its former great positive load the net 
results of regional vertical movement is notably negative. 
Procedure is the same in all four orographic cycles. Removal 
of a load through erosion is not accompanied by further upraising. 
Rolling the oceanic waters over the tract follows regional unload¬ 
ing. Maximum sedimental loading of the area is immediately 
succeeded by great uplifting. Every stage is met by phenomena 
diametrically opposed to those which isostasy logically and vitally 
demands. The isostatic hypothesis fails utterly to sustain itself 
before such an array of critical geological testimony. Geologically 
the crustal span of isostatic compensation seems not to hold for a 
cordilleran tract so wide as the state of Colorado. 
Isostatic hypothesis receives its strongest support from mathe¬ 
matics, albeit strictly theoretical. Exceeding fine certainly grinds 
the mill of mathematics. Yet, what comes out of such mill de¬ 
pends very largely upon what is fed into it. So that, concerning 
earth problems, there is, perhaps, often little to choose between 
rough guess of geologist and most painstaking calculation of 
mathematician. 
In view of recent comprehensive observation in the Rockies, 
bearing critically, it seems, upon the very foundations of isostasy, 
it appears that the mathematical equations will have to be radically 
modified in order properly to satisfy the necessary consequences 
lately derived directly from the field, or else they will have to be 
given up as purely fictitious. 
It is not at all strange that the Rocky Cordillera should on the 
one hand, so strongly belie the verity of isostasy, and, on the other 
hand, should point so conclusively to the strictly telluric nature of 
its genesis, and indeed of orogeny in general. 
Referring characteristic mountain tectonics, with which we are 
best acquainted, to the secular diminution in rate of the earth’s 
rotation, all the principal orographic features are readily and 
satisfactorily reproduced in the laboratory. At best, then, moun¬ 
tain genesis appears to be merely feeble expression of the larger 
telluric properties of our globe. Kijyes. 
Changing Sphericity of Our Barth. Strictly global aspects of 
our planet seldom appeal to earth students to the full extent which 
