DIASTROPHISM AS BASIS OF CORRELATION 301 



connected the present continents at remote stages in their history. 

 In the eariier eras, when the differentiation of platforms and basins 

 was less advanced, ridges which have since been submerged are 

 perhaps recognizable. In the interpretation of the earlier periods, 

 these should probably be restored as continental connections. In 

 the earliest known ages, these may have been rather numerous and 

 their combined area considerable, but these seem to me to be only 

 qualifying features which, by the natural place in evolution which 

 they fill, support, rather than weaken, the general conception of a 

 systematic succession of deformations in which the offspring of each 

 is the parent of the next, and in which both continents and ocean 

 basins were progressively segregated and unified. 



I trust that many of you will agree that, in general, the relatively 

 upward movements of diastrophism have been located continuously 

 in the continents, and the broad downward movements continuously 

 in the ocean basins, and that, setting aside incidental features, the 

 dominant effect of the successive diastrophic movements has been 

 to restore the capacity of the ocean basins and to rejuvenate the con- 

 tinents. This conclusion seems to me to be strongly supported by 

 the general course of geologic history, wherein sea-transgressions and 

 sea-withdrawals have constituted master features. Perhaps our 

 firmest ground for this conviction is found in the present relations of 

 the continents and the sea basins. If heterogeneity had dominated 

 continental action in the great Tertiary diastrophisms, the results 

 should stand clearly forth today. Some continents should show 

 recent general emergence, while others should show simultaneous 

 general submergence. The dominant processes today should be 

 those of depressional progress, on the one hand, and those of ascen- 

 sional progress, on the other. As a matter of fact, all the continents 

 are strikingly alike in their general physiographic attitude toward 

 the sea. They are all surrounded by a border-belt, overflowed by 

 the sea to the nearly uniform depth of 100 fathoms. These submerged 

 tracts are all crossed by channels, implying a recent emergent state. 

 None of the continents is covered widely by recent marine deposits, 

 and yet all show some measure of these. Wide recent transgressions 

 in one part do not stand in contrast with great elevations in another. 

 Even beyond what theory might lead us to expect, when we duly 



