BULLETIN OF THE GEOLOGICAL SOCIETY Of AMERICA 

 Vol. 7, pp. 377-398 March 23, 1896 



PLAINS OF MARINE AND SUBAERIAL DENUDATION 



BY W. M. DAVIS 



(Read before the Society December 27, 1895) 



CONTENTS 



Page 



Introduction 377 



The English school 378 



The American school 385 



Comparison of the two schools = 392 



Review of the a priori argument 393 



Statement of the a posteriori argument 395 



Consequences of subaerial denudation 395 



Consequences of marine denudation 396 



Examples of dissected uplands with adjusted drainage 397 



Introduction. 



Geologists today may be divided into two schools regarding the origin 

 of regions of comparatively smooth surface from which a large volume 

 of overlying rocks have been removed. These regions occur under two 

 conditions: First, as buried " oldlands " on which an unconformable 

 cover of later formations has been deposited, the oldlands being now more 

 or less locally revealed by the dissection or stripping of the cover ; second, 

 as uplands or plateaus whose once even surface is now. more or less 

 roughened by the erosion of valleys. 



The older school, now represented chiefly by English geologists, follows 

 the theory of Ramsay, and regards these even oldlands as plains of 

 marine denudation. The newer school, represented chiefly by American 

 geologists, but also by a number of continental European geologists, may 

 be said to follow Powell, who first emphatically called attention to the 

 possibility of producing plains by long continued subaerial denudation. 

 The present review of the question first cites a number of extracts from 

 various representatives of the two schools, and then seeks for a test by 



XLIV-BuLL. Geol. Soc. Am., Vol. 7, 1895. (377) 



