10 GEOLOGICAL SURVEY OF THE TERRITORIES. 



party of prospectors, the "Baker's party", had reached a section of 

 country that was said to abound in silver and gold. After enduring 

 many hardships, a portion of the men succeeded in again reaching set- 

 tlements, while others were killed by the Indians. Ten years later, the 

 mining-region was brought into public notice a second time, more par- 

 ticularly by the discovery and working of the " Little Giant" mine. 

 Since then, many prospectors and capitalists have examined the indi- 

 cations of ore, and active mining has taken the place of mere prelimi- 

 nary examination. In 1873, the tract of land supposed to contain all 

 or nearly all of the metalliferous lodes was purchased from the Ute In- 

 dians by the United States Government. It was therefore one of the 

 main objects of the San Juan division to inquire into the geological and 

 mineralogical characteristics of these lodes, with a view to obtain some 

 idea regarding their relations and value. A report thereon will be 

 found in the fourth chapter of the geological report of F. M. Endlich. 



In every respect, the country surveyed was found to be of such extra- 

 ordinary interest, and the demand for information with regard thereto 

 was so apparent, that it was deemed advisable to publish at once a por- 

 tion of the results obtained. Bulletin No. 3, of the second series, 1875, 

 contains a drainage-map of the country ; a report by A. D. Wilson, re- 

 ferring to routes, roads, grades, etc. ; one by F. M. Endlich on the mines; 

 and an itinerary, together with hypsometric data, by F. Ehoda. All 

 will be incorporated in the subjoined report in their respective places. 



While Colorado has furnished so many districts of rugged mountain 

 country, the one surveyed by this party during 1874 surpassed all. In 

 consequence of this character, it was not possible to complete so large 

 an area as was first intended, and about five thousand two hundred 

 square miles were surveyed. Of these, three thousand two hundred 

 were plotted during the winter following, and the geological report con- 

 fines itself to them. The remainder will be' attached to the work of 

 1875, thus obviating the necessity of mapping an isolated area. 



From the report and sketches accompanying, it will be seen that the 

 district was one of unusual character, containing phenomena of great 

 geological importance. Enormous quantities of volcanic rocks were 

 found to form the highest peaks, reaching an altitude of 14,280 feet 

 above sea-level, while many unique features of detail were noted in the 

 same formation. Metamorphics and sedimentaries were also observed, 

 the former rising to very considerable altitudes. As might be expected 

 in a country so favorable to the formation of water-courses, the head- 

 waters of several large streams were discovered and mapped. Among 

 the most prominent are those of the Bio Grande, Bio Animas, Bio 

 Dolores, Bio San Miguel, Bio Piedra, and the Uncompahgre. Ethno- 

 logically, the southern section was found to present interesting data. 



Through co-operation of the geological work with that of Mr. Wil- 

 son, the topographer, it became possible to render a geological map 

 that represents the horizontal distribution of the various formations 

 and their members, while sections display the vertical arrangement. 



