ON CONTINENTAL FRAGMENTATION AND THE GEO- 

 LOGIC BEARING OF THE MOON'S SURFICIAL FEA- 

 TURES ' 



By Joseph Barbell 2 



[With three plates] 



EDITORIAL PREFACE 



Considerable delay in editing parts of Professor Barren's unpublished work 

 has been unavoidable ; and as some of the articles, including the one presented 

 herewith, are of a highly speculative nature, a portion of their original interest 

 has been lost with recent progress in various fields of study. If the author 

 were living to-day. without douJit lie would make changes in tliis paper before 

 giving it to the printer. Accordingly there has been some hesitation in offering 

 the article to the public at this date. It is felt, however, that the central 

 hypothesis, stated and developed with Barren's characteristic breadth of vision, 

 is still valuable in the field of philosophical geology. Moreover, in fairness 

 to him. the full statement of his views on ocean basins should appear, as 

 preliminary brief outlines of tliese views have not been universally understood 

 and consequently have received invalid criticism. 



During his last years Barren's advanced teaching and some of his writings 



were colored with his thinking on problems of the relation between continents 



and ocean basins. His well-known studies in isostasy led naturally to an inquiry 



into the possible mechanism of continental fragmentation, a process for which 



he saw the evidence in geologic history as well as in certain tectonic features 



of the present. In 1918 he published an outline of his views in a short section 



of an article entitled " The Origin of the Earth, "^ attributing the inception 



and enlargement of ocean basins chiefly to the rise of basaltic magmas from 



the subcrust. This short preliminary treatment, and also a later summary by 



t Schuchert,* stated all essential points of the hypothesis, but without explanatory 



I detail. The proposed mechanism has been criticized on the ground that vertical 



[ intrusion can only transfer matter from one part nf the lithosphere to another, 



I without alterhig the average density and so disturbing isostatic balance. The 



i fallacy of this objection will be evident to the reader of this paper, as one 



I of Bari-ell's fundamental postulates places the source of the great basic 



I intrusions below the level of isostatic compensation. On this assumption the 



1 Reprinted, by permission, from American Journal of Science, Vol. XIII, No. 70, April, 

 I 1027. 



= Thls article is part of an unpublislied manuscript completed in the summer of 1917 



I and entitled " Tlie Genesis of the Earth," a portion of which was published by Barrell 



under the title " The Origin of the Earth " as ch. 1 in The Kvohition of the Earth and Its 



Inhabitants (Yale University Press, 1018). It has been editorially revised by Dr. C. R. 



Long-well. — C'h.\rles Schuchert. 



' Ch. I in The Evolution of the Earth and Its Inhabitants, especially pp. 39-43. 

 * Pirsson and Schuchert, Textbook of Geology, Pt. II, revised edition, p. 132, 1924. 



283 



