Geology. 607 



extending throughout North America, their dates of origin, and 

 their character are first given. Then comes a brief consideration 

 of the different theories of orogeny in their relation to the signifi- 

 cant features of the Cordillera. 



Chapter VII, the concluding essay of the volume, is by W. D. 

 Matthew and is on the Tertiary Sedimentary Record and its 

 Problems. The opening part of the chapter deals with the modes 

 of sedimentation which are involved. This is followed by a 

 discussion of the succession and correlation of the Cordilleran 

 Tertiary formations. The life record of the Tertiary, its 

 interpretation and its problems, are then taken up. This section 

 includes the place of evolution and lines of dispersal for each 

 order of mammals and the relations in time and place which are 

 held by the Cordilleran fossil Tertiary representatives. 



From this brief survey of contents it is seen that the volume 

 holds an important place in the progress of geology, elucidating 

 and evaluating the principles and relations which coordinate the 

 ever-accumulating mass of detail, and directing the further 

 progress of research which in turn makes more accurate our 

 knowledge of the past. J. b. 



2. West Virginia Geological Survey ; I. C. White, State 

 Geologist. Logan and Mingo Counties, by Ray V. Hennen and 

 David B. Reger, Assistant Geologists. Part IV, Paleontology, 

 by W. Armstrong Price, Paleontologist. Pp. 776, figures 23, 

 plates I-XV; maps I— III bound separately. Morgantown, 1914. — 

 The series of unusually complete County Reports issued by the 

 West Virginia Geological Survey has been enlarged by the publi- 

 cation of a volume devoted to Logan and Mingo counties. Like 

 its predecessors, this report contains a detailed description and 

 revision of the geologic formations (Pennsylvanian in age) ex- 

 posed, as well as a discussion of the topography, structure, and 

 paleontology. In the chapters on Economic Geology particular 

 attention is given to the outcrops and structure contours of the 

 Campbell Creek Coal bed — the celebrated " No. 2 Gass Coal " of 

 the mining engineer. h. e. g. 



3. Illinois Geological Survey; Frank W. DeWolf, Director 

 Bulletin No. 21, Lead and Zinc Deposits of Northwestern Illinois, 

 byG.H.Cox. Pp. 120, 13 figures, plates I-XXIL Urbana, 1914.— 

 The portion of Professor Cox's detailed description of the Illinois 

 lead and zinc deposits which is of most general interest is the dis- 

 cussion of ore genesis. The theory proposed, which is believed 

 to account for a variety of puzzling features, is outlined as fol- 

 lows: The ultimate source of the ores is the pre-Cambrian crys- 

 tallines of the Lake Superior region; the immediate source is the 

 Maquoketa shales on which the disseminated particles of ore were 

 originally deposited from the waters of the Ordovician sea. 

 Organic matter in the shales permitted precipitation of ore and, 

 as the shales were eroded, descending waters carried the ore par- 

 ticles downward until they came to rest in cavities of the Galena 

 limestone. h. e. g. 



