274 Joseph Barrell. 



by the Nature of Departures from Isostasy." The final 

 part has to do with the ''Physical Conditions Control- 

 ling the Nature of the Lithosphere and Asthenosphere. " 

 It is evident that Barrell intended to publish other parts 

 in this series, for we have found among his papers the 

 manuscript for Part IX on the "Problems involved in 

 the Temperature Gradient conforming to the Curve of 

 Crustal Strength." During the winter of 1914-1915 he 

 wrote still another manuscript that appears also to have 

 been intended for this series; it is entitled "Relations 

 of Pleistocene Warping to Strength of Crust." These 

 two articles we have been advised not to publish in their 

 present form; they will, however, be of service to the 

 Geological Department of Yale University. 



Pirsson says of these papers: Barrell "finds that 

 the crust is very strong when measured by its capacity 

 to support great deltas, mountain ranges or large in- 

 ternal loads due to variations in density not in accord 

 with topography, while on the other hand the altitudes 

 of the continents as a whole or in large sections show 

 nearly perfect isostasy. The maintenance of such iso- 

 static conditions through geologic time, in spite of op- 

 posing geologic activities, is held to imply the existence 

 of a zone of undertow below the zone of compensation, 

 which is both thick and weak to shearing stresses. Geo- 

 logically, such a zone, called the asthenosphere — the shell 

 of weakness — must have important bearings, which are 

 treated in the later portions of the work," 



With this biography are printed two other papers on 

 isostasy written by Barrell for this Journal, the longer 

 one having been completed shortly before his death. This 

 paper was written in answer to certain recent adverse 

 criticism of the theory. Here Barrell gives an easily 

 readable outline of the theory of isostasy, a long pre- 

 sentation of the jDroblems connected with it, and his final 

 interpretation of the isostatic data of India, the birth- 

 place of the hypothesis. 



Genesis of the Earth. 



In 1907, Barrell was aroused into criticism by Pro- 

 fessor W. H. Pickering's paper, "The Place of Origin 

 of the Moon." This place the latter thought to be the 

 Pacific Ocean, thus giving rise to that basin, an hypoth- 



