688 THOMAS CHROWDER CHAMBERLIN 
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 
connected the present continents at remote stages in their history. - 
In the earlier 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 
