December 4, 1914] 



SCIENCE 



817 



the most obtrusive and available for study; in 

 the Appalachian region and other mountain 

 districts the structural or tectonic features 

 are the more striking; in the Great Basin and 

 over the southwestern plateaus the factor of 

 aridity; in some districts, vulcanism; etc. 

 The stratigraphic and paleontologic differ- 

 ences of the several sections are quite as im- 

 portant. Some one has said that the best con- 

 versation goes on in hints, and a text-book for 

 nation-wide use must be merely suggestive on 

 many subjects. The competent college in- 

 structor must be capable of making his own 

 text-book for his own district. The tendency 

 of general text-books and treatises will be to 

 omit more and more of the elementary matter 

 as it becomes the common knowledge of edu- 

 cated people, and another class of books will 

 arise for observational and intensive study of 

 particular provinces. 



To point out minor omissions, slips or errors 

 is both ungracious and unnecessary, and few 

 are found in this book. One broad criticism 

 will be made of the references to collateral 

 literature and contemporary authors. The 

 book does not make the mistake of loading its 

 pages with a multitude of references. But 

 when they are used at all they should be dis- 

 criminating, impartial and up-to-date. Al- 

 though there are abundant references to the 

 publication of the U. S. Geological Survey and 

 to the Journal of Geology, there are compara- 

 tively few references to other literature, and 

 very few to articles of the last ten years. Yet 

 the geologic literature of the last decade is 

 large and much of it of masterly character, by 

 eminent authorities, superseding for reference 

 value much of the older writings. The geol- 

 ogists of the eastern states may feel that the 

 book has a provincial character. 



This book will be welcome to those who 

 wish a geologic philosophy based on a scien- 

 tific theory of the genesis of the globe. An 

 admirable summary is given of the three hy- 

 potheses of earth origin; the Laplacian 

 ("Nebular")) Iiockyer's meteoritie and 

 Chamberlin's planetesimal. The manner of 

 the earth's origin is the basal postulate in all 

 geophysical theories iand in most geologic 



philosophy. On very many subjects the 

 views of the geologist and his handling of 

 problems must ultimately be grounded on his 

 conception of the origin of the globe and its 

 satellite. As all geologists up to recent years, 

 and many of the more conservative at tha 

 present time, still hold to the discredited 

 hypothesis of an originally incandescent 

 globe, it will be seen that this work, like its 

 three-volume predecessor, runs counter to 

 many long-accepted theories and presents new 

 and novel explanations. 



In true scientific spirit and with some defer- 

 ence to conservatism, the authors have been 

 fair in treatment of old theories and modest 

 in presentation of the new views, usually set- 

 ting the older thought side by side with the 

 new philosophy. A few of the topics which 

 have original treatment, in consequence of the 

 new cosmogeny, are: origin and nature of the 

 deep-seated rocks ; origin of the ocean and the 

 atmosphere; origin of the sub-oceanic and 

 continental relief; diastrophism and mountain 

 structure; vulcanism; duration of life; cli- 

 matic changes; subdivision of Precambrian 

 time. Ore deposits are given a fair presenta- 

 tion under the topic " Groundwaters." The 

 chemic and biologic processes of the ocean are 

 given space instead of long description of the 

 commonplace erosional work. 



The historical portion of a text-book is the 

 most difficult to handle. Selection and con- 

 densation must be made from a vast body of 

 paleontologic fact and from uncertain or con- 

 flicting stratigraphy. And such matter is the 

 most difficult to keep up-to-date and to make 

 satisfactory to the experts. In general, this 

 matter of the book seems judicious and well 

 balanced, but the 'New York stratigraphy is 

 too old. Under the Silurian the curious mis- 

 take of Hall, Emmons and Dana in placing 

 the Oneida conglomerate beneath the Medina, 

 instead of above it, is repeated, although the 

 correction was made years ago in the New 

 York State Museum publications, and in 

 Science. 



The series of paleogeographic maps, depicting 

 the evolution of the continent, are copied with 

 some reduction from the three-volume work. 



