260 Joseph Barrell. 



low these lines. He also did much to build up the sci- 

 ence of paleoclimatology, and in paleogeography he 

 established principles for discerning the shore-lines of 

 the seas and the extent and elevation of the ancient 

 lands that were furnishing the sediments. Had he lived 

 longer, he would have done much more, and an unusual 

 opportunity for stimulating others would have come to 

 him as chairman of the new Committee on Sedimenta- 

 tion in the National Research Council. 



Probably Barrell 's most philosophic and most diffi- 

 cult work relates to isostasy. About one-sixth of his 

 publications have to do with the strength of the earth's 

 crust. He states that "The larger features of the 

 earth's surface are sustained in solid flotation," and 

 "the subcrustal shell is subjected to but little else than 

 hydrostatic pressure." Isostatic balance is, however, 

 not every^^here in adjustment, for "the outer crust is 

 very strong, capable of supporting individual mountains, 

 limited mountain ranges, and erosion features of cor- 

 responding magmtude. " 



The length of geologic time was another problem that 

 deeply interested Barrell. In his "Rhythms and the 

 Measurements of Geologic Time," he came to the con- 

 clusion that through the rhythmic oscillations of the 

 terrestrial processes which the earth has undergone, its 

 age is many times greater than even geologists in general 

 have imagined — in fact, that it is of the order of about 

 1,500 million years. 



Another line of research which occupied Barrell was 

 the origin and genesis of the earth, and here he extended 

 in modified form the Chamberlin-Moulton planetesimal 

 hj^Dothesis, i. e., that the planets and their moons arose 

 out of the sun during a time of induced tidal disruption. 

 Some of his best work was to develop along this line. 



While an undergraduate student at Lehigh, he be- 

 came interested in the physiography^ of the highlands of 

 New Jersey and Pennsylvania. He had studied Da\T.s's 

 works, but on account of the peculiarities of the rivers 

 that flow through the ridges and the many mnd-gaps 

 in the region with which he was familiar, he concluded 

 that much of the area must have been beneath the sea 

 and been covered by sedimentary deposits. This was 

 in opposition to the prevalent view that the present 

 rivers were incised in the "Cretaceous peneplain." 



