LETTER OF TRANSMITTAL. 



DEPARTMENT OF THE INTERIOR, 



UNITED STATES GEOLOGICAL SURVEY, 



Washington, D. C., March 27, 1905. 



SIR: I transmit herewith the manuscript of a report on the Geology of the 

 Tonopah Mining District of Nevada, by J. E. Spurr, and recommend its publication 

 as a professional paper. 



The geological problem presented in this district is one that could not have 

 been solved except by a trained petrographer, since the igneous rocks that carry 

 the vein deposits have been largely covered by practically barren flows of more 

 recent eruptives; hence the very careful and thorough study of the district made 

 by Mr. Spurr can hardly fail to be of great practical value to the miner, as 

 well as of scientific interest to the student of ore deposits. 

 Very respectfully, 



S. F. EMMONS, 



Geologist in Charge of Section of Metalliferous Deposits. 

 Hon. CHARLES D. WALCOTT, 



Director United States Geological Survey. 



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