REPORT OF PROGRESS IN THE GEOLOGICAL RESURVEY 

 OF THE CRIPPLE CREEK DISTRICT, COLORADO. 



By WALDEMAR LINDGREN and FREDERICK LESLIE RANSOME. 



IKTRODTTCTIOX. 



The Cripple Creek gold deposits were discovered in 1891. Shortly 

 afterwards, in 1894, an examination of the new district was undertaken 

 by the United States Geological Survey, Mr. Whitman Cross having 

 charge of geology and petrography and Mr. R. A. F. Penrose, jr., 

 undertaking the examination of the mines. Their report, accompanied 

 by a geological map, was published in the Sixteenth Annual Report of 

 the Geological Survey, Part II, pages 1-207, and has for the last ten 

 years served as a useful and accurate geological guide to mining 

 operations. 



With the astonishingly rapid development of the Cripple Creek 

 mines the opportunities for geological study multiplied, revealing 

 great complexity of vein phenomena and stimulating a desire for fur- 

 ther investigation, particularly with a view of obtaining some evidence 

 as to the persistence of the veins in depth. This desire found expres- 

 sion in a request by citizens of Colorado for a reexamination of the 

 district by the United States Geological Survey and in an offer of 

 cooperation, whereby the cost would be equally divided between the 

 State of Colorado and the National Survey. The necessary amount 

 having been subscribed in Cripple Creek, Colorado Springs, and Den- 

 ver, the State contribution was put in the hands of Mr. John Welling- 

 ton Finch, State geologist of Colorado, and by him disbursed. The 

 cordial thanks of the geologists in charge of the work are due to Mr. 

 Finch for his hearty and efficient cooperation. 



The reexamination began with a thorough revision of the topographic 

 map of Cripple Creek by Mr. R. T. Evans, Mr. E. M. Douglas in 

 charge. This involved a great deal of painstaking work, nearly every 

 prospect hole being located, as well as all shafts and tunnels. The 

 new map is on the scale of 1:19,495, or about 2i inches to the mile, 

 and includes practically the same area as the old map, a small strip 

 only being added on the western side, so that the total area mapped is 

 about 40 square miles. The small developments outside of this area 



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