18 .1. D. DANA — A.REAS OF CONTINENTAL PROGRESS. 



and, nevertheless, the orographic movements affected more or less the whole 

 belt. 



The later areas of rock-making, those of the Eocene Tertiary, which also 

 wen areas of profound subsidence, were bounded by the mountains which 

 had just before been made and put into combination with the Archaean 

 ranges. 



Ajb to rock-making within the Great Valley and the Great Basin regions, 

 and the relations of the various local subsiding troughs in the latter, more 

 facts are needed for any general conclusions. 



Prom this review of the system of progress in a case of continent-making 

 we learn that the areas of rock-making were defined for the most part in 

 Archaean time : that their confines were old Archaean ranges, or else later 

 uplifts made in accordance with the Archaean system ; that <m the Atlantic 

 border the Cambrian and Lower Silurian formations were united to the 

 Archaean so as to widen the Archaean or protaxial boundary range : and we 

 have reason to conclude also that areas were rock-making bo far and so lone 

 as they were subsiding troughs. 



It is also seen that the larger part of the work of marine waters was done 

 within interior continental seas without contributions of rock-material from 

 outside or aid from the ocean's waves or currents, either those of the Atlantic 

 or Pacific, for the most part, therefore, the growth of the continent, so far 

 a- througb marine waters, may he said to have been endogenous. It began 



to he exogenous on the Atlantic Bide in tin Creta< us era, these beds there, 



and tin' Tertiary also, being of sea-border origin; yet vastly the larger part 

 of the Cretaceous rocks of the continent, although marine, were made in 

 interior seas. 



>n the far east Paleozoic and Mesozoic area, including much of Nova 

 5 >tia and Eastern New Brunswick, had its outside Archaean boundary, and 

 was a trough of Archaean confines, not the margin of the open Bea. The 

 open Bea is a harsh region for rock-making, and only limestone-making 

 through coral growths and the associated life appears to succeed well in the 

 face of the heavy breakers. 



It is of the highest interest t" find, in such a review of events marking off 

 tin- growth of tin- continent, that the grander lineaments were well defined, 

 and the grander movements initiated, in \i< early headlining. Surely, there 

 can In- no mistake in tic conclusion that tin' continent ha- ever been a unit 

 in its system and law- of development ; or the wider conclusion that all the 

 continents " have had their law- of gr »wth involving consequent features, as 

 much a- organic structures." * 



* 



