306 DESCEIPTIVE GEOLOGY. 



toward the centre of the range, the red striped sandstones of the upper 

 Weber Quartzite are crossed, whose angle rapidly flattens out to 15° and 

 10° south. An analysis of a specimen of these sandstones, of a deep-red 

 color, with stripes of a darker coloring, about an eighth of an inch apart, 

 and composed mostly of rounded grains of quartz, was made by Mr. B. E. 

 Brewster, with the following result: 



Silica , 97.636 



Magnesia V 



Ferric oxide > 1.780 



Alumina j 



Ignition , 0.584 



100.000 



From Point Carbon, a comprehensive view of the southern spurs was 

 obtained, and the general structure easily studied. In the region between 

 the east and west branches of the Duchesne Fork, there is seen to be a 

 re-entering curve in the strata toward the axis of the range, in consequence 

 of which the steeper dips extend to a greater depth in the Weber Quartzite 

 series ; these beds can be seen lying at low angles high up on the dividing 

 ridge near the head of the canon, but bending down to the southward in 

 conformity with the steep angles of the Mesozoic beds, without any appre- 

 ciable break or want of continuity. 



The red sandstones of the Triassic can be seen extending high up on 

 the ridge, and forming the summit for some distance above the lake, their 

 strike being to the north of west; in the valley beyond, to the westward, as 

 will be seen in the description of Map III, they change in strike again, 

 bending outward with a strike to the south of west. Unfortunately, there 

 was a long interval between the time of observation of the two branches of 

 the Duchesne, the western having been visited in 1869 and the latter in 

 1871, and their correlation, with reference to the correspondence of beds, is 

 not as satisfactory as could be wished. 



