REPORT OF C. A. WHITE, M. D. 



LETTEE OF TRANSMITTAL. 



Washington, D. C, November 1, 1877. 



Sir : I have tbe honor to transmit herewith my report on the geology 

 of a portion of Northwestern Colorado, it being the district that was 

 assigned to me for examination during the season of 1876. 



The amount of time I was enabled to give to the work during that 

 season was comparatively short, and my movements in the field having 

 been dependent on those of the topographical party, the results were 

 necessarily incomplete ; but having been able to devote a part of the 

 season of 1877 to the same district, I have succeeded in working out its 

 structural geology with a good degree of satisfaction. 



My method of prosecuting the work was, besides the ordinary exam- 

 ination of the rocks and the surface of the region as I traversed it, to go 

 upon the higher and more prominent points and make my field-notes and 

 sketches there. Besides visiting all the topographic stations in this way, 

 I established many note stations of my own, also. Thus the whole dis- 

 trict was examined in detail, and every feature of its geological structure 

 was seen and traced by my own eyes; which the slight accumulation of 

 Boil or debris upon the surface and the sparseness of vegetation in that 

 arid region rendered entirely practicable. 



On a subsequent page I have correlated the general section of the 

 rocks of my own district with those prepared by Powell and King, respect- 

 ively, for adjoining districts, as I understand them after a considerable 

 personal examination of the geology of those districts. 



This report is chiefly confined to the structural geology of the district, 

 which is found to possess peculiar interest; but many interesting facts 

 were also observed concerning its economic and surface geology, drift, 

 trap-outflows, &c., which are recorded on following pages. 



Very respectfully, yours, 



C. A. WHITE. 



Dr. F. V. Hayden, 



In charge of the Geological and 



Geograj^hical Survey of the Territories. 



