286 REVIEWS 



long and from 3 to 4 miles wide. For a distance of 45 miles its depth 

 is between 575 and 900 feet below sea-level. The origin of the troughs is 

 a subject which still requires further careful work. The author does 

 not accept glacial erosion, drift deposition, or preglacial and interglacial 

 stream erosion as the sole agents of the trough-making, but advances the 

 opinion that each one, and in some cases all, of these have been causes of 

 some of the troughs. 



In Pleistocene times there were two glacial epochs, the Admiralty and 

 the Vashon, with an interglacial epoch known as the Puyallup. The 

 glacial invasions were both from the north. In the interglacial epoch 

 there was an uplift of the region about 1,000 feet above the present 

 level which was followed by stream erosion to submaturity stage. In 

 postglacial times there has been submergence of 250 to 280 feet below 

 present level and re-emergence. 



2. The bibliography mentioned above is an expansion of the bibliog- 

 raphy of Washington geology published by the Survey in 1910, and 

 includes all publications up to date with an introduction of geographical 

 material. It is provided with a full subject index. 



3. The mining district covered by the third report is about 30 miles 

 northwest from Spokane. The ore is argentiferous galena in quartz 

 veins. Pay ore has been found in few places, and the output is very 

 small. 



T. T. Q. 



1. Report of the Topographic and Geologic Survey Commission of 



Pennsylvania, 1910-1912. By Richard R. Hise. Pp. 102, 

 pis. 21, figs. 23, maps 5. 



2. Graphite Deposits of Pennsylvania. By Benjamin L. Miller. 



Topographic and Geologic Survey of Pennsylvania. Report 

 6. 1912. Pp. 143, pis. 17, map I. 



1. The first of these reports includes a bibliography of the publica- 

 tions of the state and of the United States Geological Survey relating to 

 Pennsylvania. Other appendices are: "Preliminary Report on the 

 York Valley Limestone Belt," by M. L. Jandorf; "Geological Origin 

 of the Freshwater Fauna in Pennsylvania," by Dr. A. E. Ortmann; 

 "A Peridotite Dike in Fayette and Greene Counties," by Lloyd B. 

 Smith; "The Mineral Production of Pennsylvania," by R. R. Hise. 



2. The report on graphite includes a general discussion of the history, 

 properties, occurrence, and origin of graphite, with a full statement of its 



