Geology. 77 



tory forces in mountain growth. In front of the great range 

 are foothills of folded and uplifted Pliocene strata. Beyond 

 these to the south is the great Indo-Gangetic trough of alluvium. 



Oldham has computed the effects of these several provinces on 

 the deflections of the plumb-line under the hypothesis of isostasy 

 and compared these with the actual deflections. He finds that 

 under the central part of the range the complete isostatic flota- 

 tion would require a somewhat greater elevation than now exists 

 but that the foothill range, on the contrary, is over-elevated, 

 perhaps to the extent of about 2,000 feet. The weight of this 

 over-elevated zone is given as the cause for the depression of 

 the Indo-Gangetic trough ; the latter, from the defect of gravity, 

 is concluded to be between 15,000 and 20,000 feet deep to the 

 bottom of the alluvium, the deepest part lying near the moun- 

 tains. 



The results indicate a considerable strength of the crust,, 

 enabling a load in one place to be partly supported by the sur- 

 rounding zone. The degree of isostasy found in the Himalayan 

 system as a whole, however, Oldham takes as indicating that the 

 vertical forces of uplift are more fundamental in producing the 

 regional elevations than are the horizontal forces of compres- 

 sion. The arguments against various older hypotheses are also 

 presented. j. B. 



2. The Origin and Evolution of Life; by Henry Fairfield 

 Osborn. Pp. xxxi + 322, 136 figs. New York, 1917 (Charles 

 Scribner's Sons). — This comprehensive and abundantly embel- 

 lished book seeks to synthesize all the interrelated sciences toward 

 an explanation of the origin and evolution of life, on the theory 

 of action, reaction and interaction of energy. In these Hale 

 Lectures of the National Academy of Sciences the author takes 

 "the initial steps toward an energy conception of Evolution 

 and an energy conception of Heredity and away from the matter 

 and form conceptions which have prevailed for over a century" 

 (vii). The book is symbolic of the present trend toward a cen- 

 tralization and synthesis of related sciences. It is one of the 

 first on this new road of intellectual endeavor and is a good 

 model. That this road of evolution under the energy concept 

 will be difficult and even dangerous for the pioneer travellers is 

 a foregone conclusion. This Professor Osborn knows, and when 

 on unfamiliar ground he introduces the specialist for the part 

 and allows him to revise the compiler's statements so that all 

 may be in order in the general setting of the book. The author 

 does not "pretend to offer an explanation of the miracles of 

 adaptation and of heredity, " but he recites them "to show that 

 the germ evolution is the most incomprehensible phenomenon 

 which has yet been discovered in the universe "(vii). Further, 

 that "the causes of the evolution of life are as mysterious as 

 the law of evolution is certain "(ix). 



The first chapter of the book deals with the "preparation of 

 the earth for life" in a study of the composition of the lifeless. 



