abstracts: geology 453 



GEOLOGY. — The Lake Clark-Central Kuskokwim region, Alaska. 



Philip S. Smith. U. S. Geol. Survey Bull. 655. Pp. 162, with 



maps and illustrations. 1917. 

 This report describes the areal geology of the Lake Clark-Central 

 Kuskokwim region, Alaska. The region is in southwestern Alaska and 

 extends from the Pacific ]VIountains to the central part of the Yukon 

 Plateau province. The rocks are dominantly sedimentary strata of 

 Mesozoic age, but some Paleozoic limestones are also exposed. Igneous 

 rocks both of intrusive and effusive origin occur at a number of places 

 and certain of them seem to be closely associated with deposits of com- 

 mercial value, such as gold and quicksilver. Unconsolidated deposits 

 are widespread and throughout much of the region mantle the under- 

 lying bedrock. These deposits are mainly of glacial and glacio-fluvi- 

 atile origin, though lacustrine, fluviatile, and volcanic ash deposits 

 occur also. 



P. S. S. 



GEOLOGY. — The structural and ornamental stones of Minnesota. 

 Oliver Bowles. U. S Geol. Survey Bull. 663. Pp. 225, with 

 maps and illustrations. 1918. 

 In this bulletin the history of the industry is summarized, the rocks 

 of Minnesota and their constituent minerals are described, and an 

 outline of the geologic history is given. A brief account of the proper- 

 ties essential to the usefulness of stones is followed by a general dis- 

 cussion of the crystalline rocks of Minnesota. Detailed descriptions 

 of the quarries, of their products, mode of operation, equipment, owner- 

 ship, and means of transportation, form the main body of the report. 

 The stones quarried are granite, gabbro, diabase, limestone, marble, 

 sandstone, and quartzite. As a guide for prospective operators unde- 

 veloped outcrops as well as quarries are described. 



R. W. Stone. 



GEOLOGY. — A geologic reconnaissance of the Uinta Mountains, north- 

 ern Utah, with special reference to phosphate. Alfred R. Schultz. 

 U. S. Geol. Survey Bull. 690-C. Pp. 64, with maps. 1918. 

 The rocks in the Uinta Mountain region range in age from pre- 

 Cambrian to Quaternary, inclusive. The Park City formation, in which 

 the phosphate deposits occur, and the formations immediately under- 

 lying and overlying it are described so that the phosphate-bearing beds 

 and the rocks associated with them may be compared with the phos- 

 phate-bearing beds of other localities in the Rocky Mountain region. 



