352 Scientific Intelligence. 



The volume closes with Chapter viii, "Continental Structure 

 of Asia" (pp. 115-133), a chapter full of valuable suggestion 

 even though one of hypothesis. "The analysis of Asia into con- 

 tinental elements, the interpretation of successive geographic 

 conditions, the attempt to explain the arrangement of the "leitli- 

 nien," and the statement of a source of tangential thrust are 

 contributions to theory. They are, so far as I can now judge, con- 

 sistent with the known facts, but they must stand or fall quanti- 

 tatively and qualitatively by the test of the great host of facts 

 which are yet to be gathered in the wonderful continent " (p. 

 133). c. s. 



2. Patuxent Folio, No. 152, Maryland-District of Colum- 

 bia; by George Buebank Shattuck, Benjamin" Le Rot Mil- 

 ler, and Arthur Bibbins. 12 pages text, 3 page plates, 1 page 

 geological section. IT. S. Geol. Surv., 190V. — This quadrangle, 

 of a quarter of a square degree in area, has been surveyed in 

 cooperation with the Maryland Geological Survey and fuller 

 discussions of the Maryland portion are to be found in a num- 

 ber of the reports of that state. The region lies mostly on the 

 Atlantic Coastal Plain, its northeastern quarter embracing a 

 small portion of the Piedmont Plateau, here not more than two 

 hundred feet above the sea. 



The geologic formations consist of a few outcrops of Archean 

 granite-gneiss, showing through the Cretaceous of the north- 

 west, and of Tertiary and Quaternary dejjosits of the coastal 

 plain, — these later deposits being mapped as eight formations. 

 This indicates the increased degree of refinement which in recent 

 years has marked the study of the coastal plain deposits. 



J. B. 



3. Ouray Folio, No. 153, Colorado. Geography and Gen- 

 eral Geology ; by Whitman Cross and Ernest Howe. Eco- 

 nomic Geology \>y J. D. Irving and Whitman Cross. 20 pages 

 text and geologic section, 3 pages maps, 1 page illustrations. 

 IT. S. Geol. Surv., 1907. — This folio contains the geologic maps 

 and descriptions of a sixteenth of a square degree in the neigh- 

 borhood of Ouray, Colorado. The folio is of value and interest 

 not only because of the great mineral wealth of the region, but 

 because of the rugged character of the San Juan Mountains 

 within which it is situated, and the great number of sedimentary 

 and igneous formations. 



The elevation ranges from 6800 feet in the northwest corner of 

 the quadrangle to 14,020 feet near the southeast corner. The 

 dominant features in the geology are the San Juan tuffs, forming 

 the body of the mountains, and the Mancos (Cretaceous) shale of 

 the northwestern quarter. Many other formations are exposed, 

 however, which range in age from Algonkian to Recent. 



The page of illustrations which has been added to many of 

 these westei'n folios is an extremely desirable feature, supple- 

 menting the reading matter in giving a vivid conception of the 

 district. A feature of the economic portion is the presentation 



