F. GEOGRAPHY. 263 



EXPLORATIONS UNDER DR. HAYDEN IN 1875. 



The United States Geological and Geographical Survey 

 of the Territories, under the direction of Professor Hayden, 

 during the season of 1875 continued its work of the two 

 previous seasons in Colorado, completing the southern and 

 southwestern portions, including a belt fifteen miles in width 

 of Northern New Mexico and Eastern Utah. 



The entire force of the survey was divided into seven 

 parties for special duty, four of which were assigned to spe- 

 cific areas, for the performance of topographical and geolog- 

 ical work. One party attended to the primary triangula- 

 tion, a second collected photographic views of the most in- 

 teresting scenery and ancient ruins, while a third transport- 

 ed the supplies to the various districts. 



The areas for exploration the present season were much 

 farther from the base of supplies than heretofore, rendering 

 the labor greater, and causing great loss of time in traveling 

 to and from these bases. Yet the amount of topographical 

 and geological work accomplished has not been exceeded in 

 any previous year. 



As heretofore, the starting-point was at Denver. The 

 first or southern division operated in Southeastern Colorado. 

 It was composed of A. D. Wilson, chief topographer, direct- 

 ing ; Franklin Rhoda, assistant topographer; Dr. F. M. End- 

 lich, geologist, with two packers and a cook. The district 

 surveyed by this party embraced an area of 12,400 square 

 miles. "Within these limits Mr. Wilson made one hundred 

 and forty-three stations on the more commanding peaks. 



A system of triangles was extended over the whole area, 

 while at the same time the topographical sketches and an- 

 gles were taken, barometrical readings were made at all oc- 

 cupied points, at all camps, passes, and other places of note 

 visited during the season. Many of the stations have been 

 carefully connected in height by fore and back angles of el- 

 evation and depression, to be used as a check on the baro- 

 metric heights, while the height of all located points has 

 been determined by a system of angles of depression and el- 

 evation. 



The district assigned to this division for the summer of 

 1875 joined on to the south borders of that surveyed in 



