300 THOMAS CHROWDER CHAMBERLIN 



the first depression of the abysmal basins was due to the superior 

 specific gravity of the basin-bottoms, this specific gravity remained 

 and participated in the next deformation. If the continental masses, 

 at the outset of continental formation, were relatively low in specific 

 gravity, this low specific gravity was handed down to later periods 

 and helped to renew deformation of the same phases in the same 

 regions. Under this view, ocean basins and continental elevations 

 tended toward self-perpetuation. It is not assumed that this prevented 

 shell crumplings, provincial warpings, or block movements of diverse 

 phases within the continental or the abysmal areas, for these might 

 obviously be necessary effects of the general deformative movements, 

 or at least inevitable incidents connected with the dynamics lying 

 back of them. 



A choice between these two conceptions is imperative to this 

 discussion, as they lie at the parting of the ways in the interpretation 

 of the larger events of geologic history. I accept the second view 

 with much confidence. It should be more fully qualified respecting 

 the incidental accompaniments just mentioned, but time does not 

 permit. 



According to this view, each great diastrophic movement tended 

 toward the rejuvenation of the continents and toward the firmer 

 establishment of the great basins. The distinction between con- 

 tinent and basin must not, however, be interpreted on the super- 

 ficial ground of the water-line, for the water-line merely shows that 

 the basin is over-full, just full, or under-full, as the case may be. 

 The average water-line undoubtedly helps to give a definite terrace 

 border to the abysmal basin, but the water-line freely abandons this 

 and often is far from coinciding with it. 



The base-leveling processes have shown that they are able to 

 lower the continents approximately to the sea-level in a fraction of 

 geologic time. The continents would therefore have long since dis- 

 appeared, if they had not been rejuvenated by renewed relative 

 elevation or the withdrawal of the sea. I am able to find no evidence 

 of lost continents. There are submerged margins, and matter has 

 been carried continent-ward from denuded borders. There are 

 some submerged dependencies and inter-continental connections. 

 There are also some rather deeply submerged ridges that probably 



