4 GEOEGE FERDINAND BECKER— MERRILL IMw,0,Bs tvo"xxJ; 



Soon after his appointment Doctor Becker made a reconnaissance of the San Francisco, 

 Utah, Eureka, Nevada, and Bodin, Calif., mining districts, with a view to laying out the work 

 rather than of completing the examination of any single district. Owing to a change in the 

 plans of the director, Becker personally undertook the study of the mines of the region, though 

 at a later date (1884) those of Eureka were examined and reported upon by Mr. J. S. Curtis, 

 acting as his assistant. 



Early in 1880 Becker was instructed by the director of the survey to take, in addition to 

 his survey duties, the office of a special agent of the Tenth Census (this without extra remu- 

 neration) and to assist in the compilation of statistics and technical information as to the precious 

 metal industries of the country. The district assigned included Idaho, Utah, Arizona, and the 

 country to the west of them. To S. F. Emmons was assigned the area of the Rocky Mountains. 

 This investigation extended throughout the census year. 



The results of this work were published as Volume XIII of the census reports, entitled 

 "Statistics and Technology of the Precious Metals," by Geo. F. Becker and S. F. Emmons. It 

 contained chapters on the geology of the Western States and Territories, statistics of production, 

 and a very large amount of information on most of the important features of hydraulic mining, 

 deep mining, quartz milling, etc., with brief but adequate discussions. This report, so far as 

 statistics of production are concerned, is now out of date, but the technical information for the 

 most part retains its value. 



Becker here took occasion to discuss the four ore belts of the Pacific slopes and thought to 

 show that each coincides with a well-marked zone along which relative upheaval has occurred. 

 This fact by itself he thought demonstrated that a relation existed between the great movements 

 which interest geologists and the accumulation of ore deposits which form the basis of the 

 mining industry. 



In March of 1880 Becker had been also instructed on the part of the survey to make a 

 reexamination of the Comstock lode. Messrs. F. von Richtofen, Clarence King, and J. A. 

 Church had each written reports upon the extraordinary deposit, but many features of the 

 occurrence were not satisfactorily elucidated. The importance of the occurrence and the fine 

 opportunity for study seemed to justify a fresh and more elaborate investigation. 



The work, which was carried on at the same time with the census investigation, was com- 

 pleted in two years, the report forming Monograph III (1882) of the survey series. Besides full 

 descriptions of the ore bodies and their occurrence, it contained a discussion of the rocks, show- 

 ing that the lava propylite, supposed to be the chief rock of the district, consisted in reality of 

 better-known eruptives in a peculiar state of decomposition. This, at the time, was an important 

 petrographic discovery, and particularly so in view of the work of Zirkel on the rocks of the 

 fortieth parallel survey. Examination of supposed propylites from all the other regions from 

 which geologists had collected them in the United States showed that they were all of a character 

 similar to that of the Comstock. Trachyte was shown to be absent, contrary to previously 

 expressed opinions. The heat of the lode was shown to be due to hot water, rising along the 

 vein from great depths, and deriving its heat from a source not less than 5 miles from the surface. 

 The complex "distributed faults" or "step faults" of the locality were elucidated, and it was 

 shown on mechanical principles how such were formed. Suggestions were given as to the most 

 probable position of undetected ore bodies. 



While many of the ideas put forward in this report have been the subject of controversy, it 

 may safely be said to mark a new era in geological investigations in America. No previous 

 investigations, by any survey, had been undertaken on so broad a basis. No known and avail- 

 able means of investigation were left untouched and untried. That Becker fully realized the 

 possibilities of the opportunity offered is shown by the selection of assistants, among whom 

 were the physicists, Carl Barus and William Hallock, and the then young and rising petrologist, 

 J. P. Iddings. The appearance of this monograph placed Becker in the front rank among 

 American geological investigators. 



