394: Jones — Review of Chamberlin' s Groundwork 



Introduction. 



As a groundwork for the study of "megadiastro- 

 phism," a term introduced as applying to diastrophism 

 on the large scale — continental or sub-oceanic, or even 

 applying to the earth as a whole, T. C. Chamberlin has 

 set forth in summary form in two recent papers 1 the 

 salient deductions and conclusions he has drawn from 

 his studies of the formative processes. 2 R. T. Chamber- 

 lin in a following paper 3 reviews the intimations of deep 

 deformation derived from structural cross-section studies 

 of two folded and deformed belts, the results of which 

 have been previously published. 4 



It is evident that the study in megadiastrophism is to 

 be one of the application of wedge-dynamics to continental 

 areas. To consider continental areas as the upper sur- 

 faces of deeply pointing wedges implies, of course, that 

 the earth lacks an asthenosphere or yield zone. This 

 postulate is fundamental. The issue is thus sharply 

 drawn between the two schools of thought. The basic 

 problems of diastrophism, isostasy, and vulcanism must 

 be attacked and interpreted in two diametrically opposite 

 ways by the two schools. The one school, as represented 

 by T. C. and R. T. Chamberlin, interpret these prob- 

 lems from the viewpoint of an earth which has maintained 

 perfect solidity through the formative eras and down to 

 the present; an earth, heterogeneous in its makeup both 

 laterally and in depth, in which, as R. T. Chamberlin 

 says, 5 "all thought of easy movement in the interior is 

 to be scrupulously avoided.' ' The other school, as rep- 

 resented by Daly and the late Barrell, interpret these 

 problems, on the other hand, from the viewpoint of an 



1 Groundwork for the Study of Megadiastrophism, Pt. I. Summary state- 

 ment of the groundwork already laid. T. C. Chamberlin, Jour. Geology, vol. 

 29, pp. 391-416, 1921. 



Groundwork for the Earth's Diastrophism, T. C. Chamberlin, Bull. Geol. 

 Soc. America, vol. 32, pp. 197-210, 1921. 



2 Thirteen papers in recent volumes Journal of Geology. 



3 Groundwork for the Study of Megadiastrophism, Pt. II. The Intima- 

 tion of Shell Deformation, R. T. Chamberlin, Jour. Geology, vol. 29, pp. 

 416-425, 1921. 



4 R. T. Chamberlin : The Appalachian Folds of Central Pennsylvania, Jour. 

 Geology, vol. 18, pp. 228-251, 1910. 



The Building of the Colorado Eockies, Jour. Geology, vol. 27, pp. 145- 

 164; 225-251, 1919. 



5 Jour. Geology, vol. 29, p. 421, 1921. 



