Geology and Natural History. 161 



no new views are advanced, but the author suggests that the 

 dome structure may, perhaps, be due to anticlinal arches in the 

 strata that originally overlaid the granites. 



The second part of the work, by Dale, is devoted to a descrip- 

 tion of the various quarries in the state and to their products. 

 In many instances their location is shown by small maps and the 

 geologic features are described in detail with the aid of diagrams. 

 In nearly all cases the result of a study of the rocks in thin 

 section are briefly given, and where available, chemical analyses 

 are added. 



While the main value of the work is on the economic side 

 and it should prove itself technically useful to those engaged in 

 the industry, there is nevertheless much of interest and impor- 

 tance to the geologist and petrographer that is not merely local, 

 but genera], in its application. l. v. p. 



3. The Mount McKinley Region, Alaska; by Alfred H. 

 Brooks. With Descriptions of the Igneous Rocks and of the 

 Bonnifield and Kantishna Districts ; by L. M. Priistdle. Prof. 

 Paper 70, IT. S. Geol. Surv., 4°, pp. 234, pis. 18, 3 maps. Washing- 

 ton, 1911. — In his preface Mr. Brooks, who has long been known 

 for his explorations and pioneer geologic work in Alaska, states 

 that the object of the volume is to give to geologists an epitome 

 of its stratigraphy, structure, and geologic history, and to furnish, 

 the prospector with a concise summary of present knowledge of 

 its mineral wealth. Available information regarding the climate, 

 vegetation, agricultural land, wild animals, and means of commu- 

 nication is added for the benefit of intending hunters and settlers. 

 It would be impossible in a brief notice to give any adequate 

 account of the large amount of information which this volume 

 contains in succinct form. It represents a compendium of the 

 labors in the field of a number of workers, chief of whom has 

 been the senior author. The results of the reconnaissances here 

 given will be of great value in the future when more detailed 

 work is undertaken. l. v. p. 



4. Bulletin of the Seism olog iced Society of America. — The 

 Fourth number of volume I, recently issued, contains among 

 other articles, one on the California earthquake of July 1, 1911, 

 by E. C. Templeto^. The shock, although not to be compared 

 with that of 1906, was the most severe that has been felt since 

 then, and was felt over an area whose maximum dimension was 

 about four hundred miles, extending from Sacramento to Los 

 Angeles. It was most severe in the region of San Francisco Bay. 

 The shock came without preliminary tremor, and consisted of 

 "two rather distinct periods of vibration, of which the first, with 

 a duration of between five and eight seconds, was the more intense. 

 After a lull of about five seconds came the second period of vibra- 

 tion, with a duration of about five seconds. The shock was 

 accompanied by a dull, rumbling sound, described as similar to 

 the roar of a distant railway train, the sound preceding the shock 

 by two or three seconds." ..." The maximum intensity occurred 



