208 REVIEWS 



greatly the value of the book for students in America, who will find it 

 very useful for this reason. 



The alteration in the title of the second group of igneous rocks, 

 according to the classification followed in this book, namely, from that 

 of Intrusive to that of Hypabyssal, has not obviated the necessity for 

 the apology made in the introduction to this group of rocks in the 

 first edition, which is repeated in the second. The newer term is as 

 inappropriate as the former one, and the criticism made in the review 

 of the first edition holds with equal force in the present case. 



J- P. I. 



Rocks, Rock Weathering and Soils. By G. P. Merrill. 8vo. 411 

 pp., Macmillan & Company, New York, 1897. 



This admirable work brings together three subjects closely con- 

 secutive in the processes of nature but not previously associated 

 as the subject of equally elaborate treatment in their mutual rela- 

 tions. The main emphasis of the work is placed on rock weathering, 

 the description of rocks being in the main preliminary to this and that 

 of soils a natural sequence. No attempt is made to treat rocks as such 

 in an exhaustive way, nor soils as such. The discussion of weathering 

 on the other hand is made as exhaustive as the present state of science 

 will permit. The 168 pages of Parts 1 and 2 relating to minerals and 

 rocks embrace a reasonably satisfactory treatment of these themes. 

 This is as much perhaps as can be said of any attempt in this line in 

 the present unfortunate condition of the classification and nomenclature 

 of rocks and minerals. The relative fullness of treatment of the several 

 rocks is measured in a degree by their importance in the production 

 of soils. Very properly prominence is given to chemical composition, 

 since this is a prime consideration in following the transition of the 

 rocks into soils and secondary rocks. The numerous tables of analyses 

 are a valuable feature. The use of terms is conservative and many of 

 the intermediate stages in the gradation of one rock into another are 

 left without specific nomenclature. The author files a protest against 

 the tendency " which has resulted already in such monstrosities of 

 nomenclature as onachitite,monchiquite, yogosite and absarokitey 



The subject of weathering and transportation occupies the heart of 

 the book and constitutes its distinguishing feature. After a statement 

 of the principles of weathering and of the agencies involved, the special 



