TRIASSIC PORTION OF SHINARUMP GROUP 103 



there was probably a considerable difference in age between the 

 silicified wood of the upper and lower parts of the group. 



Without detailed description and with no suggestion of variation 

 in character, Powell affirms the wide extension of the Shinarump 

 group in the following sentence: 



The variegated beds above and below the [Shinarump] conglomerate are seen 

 in many places on either flank of the Uinta Mountains, and from time to time 

 this horizon is brought up by faults or flexures in all the stretch of country which 

 intervenes between the Shinarump Cliffs and the Uinta Mountains. [23, p, 54]. 

 .... [With regard to the Shinarump conglomerate, Powell does acknowledge 

 that it is not easily recognizable, toward the north about twenty feet in thickness, 

 but increasing southward untfl it attains two hundred feet (23, p. 41).] 



The Shinarump as treated hy Button in 1880. — A treatment of 

 the Shinarump group very similar to that of Powell was given by 

 Dutton in 1880 in his Geology of the High Plateaus of Utah (6). 

 The range given to the group is the same, and on account of the 

 constancy of character few descriptive details are given. Dutton 

 thus introduces the discussion of the Shinarump: 



Resting everywhere upon the Carboniferous of the Plateau country is a series 

 of sandy shales, which in some respects are the most extraordinary group of strata 



in the West, and perhaps the most extraordinary in the world There are 



especially three characteristics, either one of which would render them in the highest 

 degree conspicuous, curious, and entertaining. First may be mentioned the 

 constancy with which the component members of the series preserve their char- 

 acters throughout the entire province. Wherever their proper horizon is exposed 

 they are always disclosed, and the same well-known features are presented in 

 southwestern Utah, in central Utah, around the junction of the Grand and the 

 Green, in the San Rafael Swell, and at the base of the Uinta Mountains. As 

 we pass from one of these localities to another, not a line seems to have disappeared, 



not a color to have deepened or paled The constancy is, so far as known 



to me, without a parallel in any formation in any other region (6, p. 144). 



Only slight changes in thickness and in constitution are admitted. 

 The varied coloration of different beds and the architectural forms 

 resulting from erosion are the other two marked characteristics. 



The constancy in lithologic character, the wonderful coloring, 

 and the peculiar architecture of erosional forms here emphasized, all 

 avowedly pertain to the lower part of the group, recognized by Dutton 

 two years later as belonging to the Permian. 





