Reviews. 



Elements of Geology. By Joseph Le Conte. Revised and partly 

 rewritten by Herman Le Roy Fairchild. Fifth edition. 

 New York: D. Appleton & Co. Pp. xii+667. 



FoK a quarter of a century Le Conte's Geology has been largely 

 used as a text-book in colleges, and as a work for the general reader. 

 The high standing which the author had as a geologist and as a teacher, 

 the literary excellence of his writings, and the even balancing of the 

 divisions of the subject have all conspired to make Le Conte's text- 

 book a popular one. Students and teachers of geology will be pleased 

 to know that the book has lately been revised and in part rewritten by 

 Professor H. L. Fairchild, head of the department of geology at the 

 University of Rochester and for a long time secretary of the Geological 

 Society of America. 



In its general appearance, form, and style very few or no alterations 

 in the book have been made. Advancing knowledge has required, of 

 course, that many changes be made in the text, some of them of minor 

 import and scarcely noticeable in a casual examination, while other 

 changes are profound and indicate radical departures from what has 

 heretofore been taught. Among the latter may be noted the substitu- 

 tion of the planetesimal theory of Chamberlin to account for the origin 

 of the earth, instead of the Laplacian hypothesis that has been so long 

 accepted. 



The paging of the new edition practically conforms to that of the 

 previous one. This has been done largely by a judicious withdrawal 

 of some paragraphs and sections, and the addition of new ones that 

 correspond in length. Many new cuts have been added, and a number 

 of the sketches and drawings in the previous edition have given way to 

 photographs. A few of the graphical illustrations or mathematical 

 diagrams have been omitted. In the chapter on metamorphic rocks a 

 number of changes have been made. Some additional varieties of 

 these rocks have been described, the section on the origin of granite 

 has been omitted, and the theory of metamorphism has been rewritten. 

 In the historical division some new figures have been added, and 

 changes in classification have been made to conform to later researches. 



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