Geology and Natural History. 401 



The book is well and abundantly illustrated and is accompanied 

 by two detailed maps of the region. An introductory outline 

 which serves to give a brief summary of the different chapters is 

 included. w. e. e. 



Bulletin No. 208. Descriptive Geology of Nevada South of 

 the Fortieth Parallel and Adjacent Portions of California ; by 

 Josiah Edward Spurr. 222 pp., 8 pis., '22 figs. — One of the 

 gaps in the geologic map of the United States which has been 

 heretofore unfilled is southern Nevada. This area has now been 

 mapped in a preliminary way as part of the plan to publish a new 

 general geologic map of the United States on the scale of about 

 40 miles to the inch. Mr. Spurr has confined himself to descrip- 

 tive matter and has included in his bulletin the results of the 

 geological explorations of Wheeler (1866), Gilbert (1871) and 

 other workers. 



No. 218. The Coal Resources of the Yukon, Alaska ; by Arthur 

 J. Collier. 67 pp., 6 pis., 3 figs. — Coal of commercial impor- 

 tance is found at many places along the Yukon River. It occurs 

 in sandstones of Eocene and Upper Cretaceous age. The coal 

 thus far mined ranges from high grade lignite to " rather low 

 grade bituminous." The coal beds are sufficient to supply local 

 demands but " will probably never supply coal for exportation." 

 Fossils, many of them entirely new, were collected from fifty- 

 three localities and have been studied by Drs. Stanton and 

 Knowlton and Mr. Schuchert. 



No. 219. The Ore Deposits of Tonopah, Nevada; by J. E. 

 Spurr. 28 pp., 1 pi., 4 figs. — A detailed final report of the inter- 

 esting Tonopah region from which |4,000,000 were taken the first 

 season will be issued later, and the present bulletin gives only gen- 

 eral outlines. The rocks in the immediate vicinity of Tonopah 

 are Tertiary andesite, dacite, rhyolite and basalt with accompany- 

 ing tuffs. The veins occur in the earliest andesite, and after a 

 period of erosion were capped by later lavas. " The veins were 

 formed by ascending waters succeeding and connected with the 

 early andesite intrusion." There were four periods of hot spring 

 action accompanied by vein formation and mineralization and 

 each of these periods was consequent upon lava intrusion. The 

 ore is gold and silver in the proportion of about 1 : 100 and is 

 unusually free from base metals. 



No. 220. Mineral Analyses from the Laboratories of the U. S. 

 Geological Survey, 1880 to 1903; tabulated by F. W. Clarke, 

 chief chemist. 114 pp. — 507 analyses of minerals of over 150 dis- 

 tinct species have been collected from the laboratory records, and 

 published in one bulletin for convenient reference. 



No. 221. Bibliography and Index of North American Geology, 

 Palaeontology, Petrology and Mineralogy for the year 1902 ; by 

 F. B. Weeks. 200 pp. 



No. 222. Catalogue and Index of the Publications of the Hay- 

 den, King, Powell and Wheeler Surveys ; by L. F. Schmeckebier.. 

 208 pp. — The early surveys of the Western United States include 



