DIASTROPHISM AND THE FORMATIVE PROCESSES 7 



old formations on any great circle of the earth. That it was large, 

 however, goes without the saying. 



But, taken at their best, the deformations in these two fields 

 are merely surficial. Such foldings as are accessible are mere 

 wrinklings of the skin of the earth body, mere hneaments of the 

 face of the earth. They have about the same relation to the 

 effective framework of the earth body as the shriveled integument 

 of an old man has to the bony skeleton that chiefly gives form to 

 his figure. 



III. The deeper deformations of the earth have been little more 

 than a field for the imagination thus far. And yet they have given 

 rise to indirect and implied evidences. There are the protrusions 

 of the continents, the sags of the sub-oceanic basins, and the general 

 configurations of the globe. There are tidal, seismic, magnetic, 

 and other dynamic lines of approach. Great light has been thrown 

 on the problems of the interior by the brilliant determination of 

 the value and nature of the body tide and the elastic rigidity of the 

 earth by Michelson and Gale on the experimental side,^ and Moulton 

 on the mathematical side.^ The seismic evidences gathered by 

 many observers indicate that the elasticity of the earth increases 

 downward faster than the density for at least a depth that involves 

 much more than half the volume of the earth. These trenchant 

 determinations bear vitally on the interpretation of the internal 

 deformation of the earth. 



The lines of approach now available for an interpretation of the 

 master-features of. the earth's surface promise at least some insight 

 of value into the earth's fundamental diastrophism. I have 

 ventured to interpret these master-features as simply the adult 

 products of a segmentation that sprang from primitive shrinkage 

 stimulated and shaped by oscillating rotation and tidal strains.^ 

 Under this view there are cogent reasons for assuming that the 

 original segments were more or less unequal and asymmetric, and 



'A. A. Michelson and H. G. Gale, "The Rigidity of the Earth," Jour, of Geo!., 

 I (i9i9),pp. 585-601. 



2 F. R. Moulton, "Theory of Tides in Pipes on a Rigid Earth," Astrophys. Jour., 

 L (i9i9),pp. 346-55. 



3 The Origin of the Earth (1916), pp. 200-224. 



