DIASTROPHISM AS BASIS OF CORRELATION 299 



the edge of the oceanic waters, whether they agree with the edge of 

 the abysmal basins or not, form the chief Hne of demarkation between 

 the great erosions and the great depositions the world over. It is 

 not the only line of such demarkation, to be sure, for degradation 

 gives place to aggradation at many other local horizons, but in this 

 discussion let us agree to deal only with factors of the larger order 

 and to neglect incidentals; let us deal with body deformation, rather 

 than local or provincial warpings. We all recognize further that the 

 sea-level is not only a dividing plane between two great divisions of 

 physical agencies, but between two great biological divisions. 



To this list of agreements, there are two other propositions which 

 we cannot add quite so unhesitatingly, because we need to weigh them 

 well, and if we cannot all agree respecting them, we must agree to 

 differ, for they are fundamental to the further discussion. These 

 relate to the effects of body deformation on the relations of land and 

 sea. 



If deformation were confined to the abysmal bottoms and were 

 compensatory, no effect would be felt on the relations of land and 

 sea. If deformation were confined wholly to the interior of the 

 continents, it would be similarly ineffectual. Deformations so 

 limited are, however, likely to be only provincial, and fall outside 

 our discussion. 



There remain two conceptions of general or body deformation 

 between which choice must be made. In the one, the deformations 

 are supposed to be indifferent to their predecessors, and to disregard 

 the configurations produced by previous deformations. Their suc- 

 cessive effects upon continental outlines and basin capacities are 

 thus heterogeneous and the combined results irregular and uncertain. 

 It is not clear to me how they can be made a very trustworthy basis 

 of systematic correlation. The submergent phase of one continent 

 or fraction of a continent may, in this case, be contemporaneous with 

 the emergent phase of another continent or fraction of a continent, 

 and the progress of events on one continent is as likely to be contrasted 

 with those of another continent as to fall in with them co-ordinatelv. 



According to the other view, deformations are inheritances, one 

 of which follows another in due dynamical kinship. The succession 

 is therefore homogeneous and the results co-ordinate. If, for example, 



