PROCEEDINGS 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY 



HELD AT PHILADELPHIA 

 FOR PROMOTING USEFUL KNOWLEDGE 



Vol. LIV September, 1915 No. 219 



SYMPOSIUM ON THE EARTH: ITS FIGURE, DIMEN- 

 SIONS AND THE CONSTITUTION OF ITS 

 INTERIOR. 



I. 



THE INTERIOR OF THE EARTH FROM THE VIEWPOINT 



OF GEOLOGY.i 



By T. C. CHAMBERLIN. 

 (Read April 24, 191 5.) 



For some time past there has been a marked drift of geologic 

 opinion from the older tenet of a molten earth toward the convic- 

 tion that the earth is essentially solid. This has been quite as much 

 due to the contributions of kindred sciences as to the growth of 

 geologic evidence, but this has made its important and concurrent 

 contributions. 



The great granitic embossments that constitute the most dis- 

 tinctive feature of the oldest known terranes were formerly re- 

 garded as solidified portions of a primitive molten earth and seemed 

 to serve as witnesses of the verity of the former liquid state. A 

 few years ago, however, it was determined — almost simultaneously 

 in several countries where critical studies on these formations were 



1 The discussion of this topic at the session of the Society was without 

 manuscript or notes and this paper, prepared some weeks later, is less a 

 reproduction of the original discussion than a substitute for it. 



PROC. AMER. PHIL. SOC., LIV. 219 S, PRINTED SEPT. 4, I915. 



