JURA TRIAS GROUPS. 



the last mentioned region, as the area of the outcrop of all of the Jura Trias 

 beds has its topography cut up so minutely by reason of many minor dis- 

 placements and transverse lines of erosion that only a generalized represen- 

 tation could be given. 



There is an island of Shinarump beds south of Echo Park, lying at the 

 foot of the Yampa Plateau. 



VERMILION CLIFF, WHITE CLIFF, AND FLAMING GORGE GROUPS 



In this region the Vermilion Cliff and White Cliff Groups are massive 

 sandstones, and hence stand in monoclinal ridges. Sometimes the base of 

 the White Cliff Group is a series of softer beds, and two ridges are formed. 

 Elsewhere the White Cliff Group rises high over the Vermilion Cliff beds in 

 a wall which faces the axis of the Uiiita upheaval on either side. Through- 

 out this entire region the White Cliff sandstone is lighter colored than the 

 Vermilion Cliff Group and everywhere exhibits that oblique structure known 

 as false bedding. 



The Flaming Gorge Group with its limestones and sandstones is of 

 heterogeneous stratification and breaks down into comparatively low hills, , 

 which are found on the backs of the great White Cliff ridges. The area of 

 outcrop is parallel and coextensive with that of the Shinarump Group, except 

 in the region near Flaming Gorge and the district immediately south of Echo 

 Park. 



About four miles southeast from Diamond Peak there is a small outcrop 

 of the Flaming Gorge beds standing on edge, with the summit of the group 

 'facing the plateau or axis of the Uinta upheaval. 



It is an interesting fact that the bad-land sandstones of the Flaming 

 Gorge Group, both above and below the Mid-Group Limestone, are of fresh- 

 water origin. 



The following is a section of the Jura Trias groups, made in the hills 

 and cliffs west of Flaming Gorge and beginning above at the base of the 

 conglomerate which underlies the teleost shales, and extending- to the summit 



O / d 



of the Bellerophon Limestone. In this region the limits of the section can 

 be easily determined. 



