NOVEMBEK 8, 1895.] 



SCIENCE. 



633 



Fields in West Virginia, Joseph D. Weeks, pp. 

 573-590. 



The first paper has popular interest but no 

 geological importance. The second is an excel- 

 lent summary of the country's mineral springs 

 and will be often serviceable for reference. A 

 list of the leading ones by States is included. 

 The third paper has valuable data on the 

 amount of flow in Western rivers, and on the 

 Potomac, Connecticut and Savannah in the East. 

 It will aid in the advancement of irrigation 

 in the West, and our general hypsometric 

 knowledge. The fourth paper is a most impor- 

 tant contribution to the geology and petrog- 

 raphy of the area discussed. It shows the great 

 part played by laccolites in some of the best 

 known Colorado mountains and the close paral- 

 lelism that exists among them all in the character 

 of the rocks. In the fifth paper Mr. Lindgren 

 ably discusses the interesting gold-quartz veins 

 of the Ophir district, Placer county, and draws 

 some well based conclusions as to their method 

 of origin. In the sixth paper Mr. Keith brings 

 out a vast amount of new and important knowl- 

 edge about the metamorphic and paleozoic belt 

 that passes fi-om Pennsylvania south through 

 Hagerstown and Harper's Ferry, Md., and 

 across West Virginia and Virginia to the Rap- 

 pahannock River. Besides describing the local 

 structural geology, and its development the pa- 

 per includes an important contribution to the 

 dynamic metamorphism of pre-Cambrian igne- 

 ous rocks, both jJlutonic and volcanic. In the 

 seventh paper Mr. Diller takes up the Tertiary 

 changes in that most interesting problem, the 

 recent geological history of the Pacific coast. 

 The ancient base levels are traced and many im- 

 portant conclusions are deduced, which have a 

 close connection with the auriferous gravels. 

 Mr. Turner's paper (the eighth) presents an ad- 

 mirable review of the geology of the Sierras and 

 adds greatly to our knowledge of their petrog- 

 raphy. In the first part of the ninth paper Mr. 

 Walcott describes the relations of the pre-Cam- 

 brian lava sheets to the other Algonkian ter- 

 ranes of the Grand Canyon, and gives detailed 

 sections and views. Prof. Iddings identifies 

 them as surface or submarine fiows of basalt. In 

 the tenth and eleventh papers Prof. Dale ex- 

 tends the area covered by his previously pub- 



lished work in the metamorphic belt of the New 

 York and New England border and especially in 

 the latter, clears up the geology of a mountain 

 famous alike for its geology and lovely scenery. 

 Both papers are also important contributions to 

 our knowledge of the mineralogical changes in- 

 volved in the passage of sediments into schists 

 and marbles. In the last paper Mr. Weeks de- 

 scribes, under the name of the Potomac basin, 

 the important coal field that extends from Wel- 

 lersburg, Pa., across Maryland into West Vir- 

 ginia, and that embraces the Cumberland or 

 George's Creek coal of Maryland, and the Elk 

 Garden and Upper Potomac coals of West 

 Virginia. Analyses, sections and statistics are 

 given. 



The Production of Tin in Various Parts of the 

 World. By Charles M. Rolker. Advance 

 excerpt from the Sixteenth Annual Report of 

 the Director of the U. S. Geological Survey. 

 1894-1895. Part III. Mineral Resources of 

 the United States. Calendar Year. 1894. 

 Pp. 1-88. 



It would appear from the above reference 

 that the forthcoming annual reports of the Di- 

 rector of the Survey are to have a regular depart- 

 ment devoted to Mineral Resources. This is to 

 be warmly commended, both because it affords 

 material that is of value to the general public, 

 which is after all the Survey's real constituency, 

 and because it caters to the scientific public 

 as well. Many friends of the Survey have 

 viewed with regret in recent years the small 

 prominence that this portion of its work has 

 received, and have felt that it was a mistaken 

 policy. 



Mr. Rolker gives an admirable and concise 

 review of tin ores, their geology, statistics and 

 the expense of production the world over. The 

 report covers much the same ground in many 

 respects as that treated by Professor Ed. Reyer 

 in his ' Zinn, eine geologisoh-montanistisch-his- 

 torische Monografle,' that appeared in Berlin 

 in 1881, but Mr. Rolker brings the subject down 

 to date, omits many theoretical discussions and 

 makes especially prominent those points that 

 are of importance in their practical relations. 

 The geology of cassiterite is curiously uniform, 

 wherever the mineral is found. Veins in or 



