ESCALANTE HILLS AND YAMPA PLATEAU. 283 



mit and southern slopes are covered with the drab limestones of the Upper 

 Coal-Measures dipping 35° south. 



On the southern flanks of the ridge, toward Lily's Park, the horizontal 

 beds of the Avliite Tertiaries cover the higher Mesozoic beds, but in the 

 deeper cuts the conformable red sandstones of the Triassic are exposed. 

 At the eastern end of Lily's Park are excellent exposures of most of 

 these upper members, curving sharply around frOrn a northeasterly strike, 

 on the north side of tlie river, to north and south at the entrance of Yampa 

 Canon, bending to the southwest, south of the river, and curving again to 

 the westward south of the White River divide. This curviiig strike is 

 best marked by the upper bed of massive sandstone of the Triassic, alwaj's 

 a prominent feature in the topography ; the sandstone on the north of the 

 river is of a yellowish-buff color, but, in the ridges to the south, the usual 

 red hue predonainates. On the White River Ridge, south of Lily's Park, 

 the low divide has been worn out of the softer clay beds of the Colorado 

 group, the sandstones of the Upper Cretaceous series to the east being in 

 general concealed by the overlying Tertiaries, The re-entering curve of 

 these outcrops suggests the structure of the hills immediately to the west, 

 which is that of a double anticlinal fold enclosing the synclinal valley, 

 through which the Yampa River now flows in a deep canon. 



The high plateau tegion of the Uinta west of this meridian is one of 

 peculiar structural interest, all the details of which were not fully worked 

 out. Its general outlines might be expressed by tliree metidional sections 

 at different points: on the meridian of 108° 30', the section would be that 

 of a single anticlinal fold; on the meridian of 180° 45', two anticlinal folds 

 with an included synclinal ; while on the line of the Western edge of the east 

 half of the map would be three anticlinal folds and two included synclinal 

 folds. This general system of east and west folds has been much complicated 

 by foldings at right angles, and by dislocations, more particularly in the 

 vicinity of the Green River, all of which will be explained as far as obser- 

 vation has succeeded in unravelling them. The Escalante Hills, as we have 

 seen, represent the southern member of the broad general fold of the Uinta 

 Range. On their northern face, and in general along the plateau summit, 

 are exposed the underlying beds of the Uinta quartzite dipping about 10° 

 to the southward. The beds of the Upper Coal-Measure limestones, over- 



