XVIII EEPORT UNITED STATES GEOLOGICAL SURVEY. 



lied Beds ; on the north side the No. 1 Cretaceous sandstone forms a 

 hogback, sloping toward the cliffs. Between the crest of this hogback 

 and the cliffs there is a broad valley formed by the erosion of the soft 

 Cretaceous shales which extend to the base of the cliffs, and in some 

 places form their lower portion. The cliffs are composed mainly of 

 Cretaceous beds, rising one above another in steps until an elevation of 

 about 8,000 feet is reached. The summit is the edge of a plateau slop- 

 ing to N. N. E. This plateau is cut by the drainage flowing into the 

 White Eiver from the south. These streams rarely cut through the 

 Tertiary series. 



Coal of poor quality is found in the sandstones of the Dakota group, 

 and also in the sandstones above the Middle Cretaceous beds. Wher- 

 ever noticed it was in their seams, and of little economic importance. 



The White Eiver division was directed by G. B. Chittenden, as topog- 

 rapher, accompanied by F. M. Endlich, as geologist. 



The district assigned to this party as their field for exploration during 

 the season of 1876, comm.enced on the eastward at longitude 107^ 30', 

 joining on to the work previously done, and extended westward 30 miles 

 into Utah Territory. Its southern boundary was N. latitude 39° 38', 

 while the White Eiver formed the northern limit. In order to complete 

 to the greatest possible advantage in the short time that could be al- 

 lowed, it was determined to make the White Eiver agency headquarters, 

 and in two trips from there finish the work. About 3,800 square miles 

 comprised the area surveyed. 



In working up the topography of this district the party spent 48 days 

 of absolute field-work, made 41 main topographical stations and 16 auxil- 

 iary ones, and traveled within the district about 1,000 miles. The party 

 ascertained the courses of all the main trails, the location and quality of 

 almost all the water, which is scanty throughout, andean map with con- 

 siderable accuracy the topographical forms and all the water-courses. 

 The area is almost entirely devoid of topographical " points," and the 

 topographer is obliged to depend to a considerable degree on those far 

 to the north and south for the triangulation. The country has hereto- 

 fore been almost entirely unexplored, and was described by the nearest 

 settlers as a broken caiion country, extremely dry. It was marked on 

 the maps as a high, undulating plateau, with fresh-water lakes and 

 timber. The party saw no lakes of more than 400 yards in diameter, 

 and only two or three of these. The country is nearly all inhabitable, 

 both winter and summer, and considerable portions of it valuable j and 

 though three-quarters of it is within the Ute Indian reservation, the 

 advantage of a more accurate knowledge of its character can readily 

 be seen. 



While working in the low, broken country of southwestern Colorado, 

 last year, Mr. Chittenden made use of a light, portable plane-table, and 

 found it of great value. It appeared at that time that its value was 

 greatest in that class of country, and that in a low, rolling district, with 



