REPORT 



OF 



F. M. ENDLICH, S. N. D. 



TVashingtoNj D. C.J June 1, 1874. 



Sir : I have the honor herewith to submit my report for 1873. As 

 directed, the mines of Gilpin, Clear Creek, and Boulder Counties were 

 first visited by me, with the view to study their geological and minera- 

 logical relations, as well those referring to the ore-veins as a whole 

 as those they bear to the surrounding rocks. In almost every instance 

 where time and the condition of the mine permitted it, a personal 

 examination of the conditions under ground was made, and the report 

 confines itself chiefly to those lodes and mines that have been thus vis- 

 ited. On July 3, I took \he field as the geologist of the San Luis di- 

 vision, returning from it to Denver on Ociober 5. I:i}"early 7,600 square 

 miles were surveyed topographically and geologically during that time, 

 and the results of the examinations relating to the geognostic and geo- 

 logical features of the country are laid before yoti in the subjoined 

 report. It is evident that on a survey of this kind, where a large area 

 must be traversed in a comparatively short time, geological research 

 cannot be carried on in as much detail as might appear desirable to the 

 investigator. By working in perfect unison, however, with the topog- 

 rapher, the geologist will be able to form a correct idea of the hori- 

 zontal and vertical distribution of formations in a very short time. 



Four chapters and an appendix comprise the annexed report. The 

 first chapter treats of the mining-regions ; and I beg leave to submit it 

 merely as a preliminary report, in the hope that at some fnture day I 

 may be enabled to make more thorough and extensive examinations. 

 The three following chapters are devoted to the geology and geognosy 

 of the district assigned to the San Luis division. In the appendix, " Min- 

 eralogical notes" and a "^^ Catalogue of the minerals of Colorado" are con- 

 tained. 



At this place, I wish to express my sincere thanks to Mr. A. D. Wil- 

 son and Mr. G. B. Chittenden, the topographers of the party, for their 

 hearty good-will and co-operation during the field-season, and to the 

 latter for the kindness with which he supplied me during the winter 

 with the illustrations nece.ssary for the report. 



To Prof. F. L. Schirmer, of Denver, and Mr. A. von Schultz, Mr. J. 

 Alden Smith, and Mr. Smart, of Central, Col., I am greatly indebted for 

 courtesies shown me. 



Hoping that the report may meet your requirements, I have the honor 

 to remain, your obedient servant, 



FEEDEEIC M. ENDLICH. 



Dr. F. V. Hayden, 

 Geologist-in-Charge, 



United States Geological and GeograpJiical 



Survey of the Territories. 



