196 DESCRIPTIVE GEOLOGY. 



scored by deep, narrow canons. Plate II represents a view of this eastern 

 summit region, looking westward across the canon of Lodore from its eastern 

 wall. What this portion of the range loses in height, it gains in breadth, 

 since the Owi-yn-huts and Yampa Plateaus may be considered properly to 

 form part of the Uinta Range. The former, whose summits attain an equal 

 eleyation with those of the central ridge, viz., of over 9,000 feet, is separated 

 from it by the deep valley of Brown's Park, whose walls are so steep, and 

 present such close correspondence in outline, as almost to suggest that it 

 was. formed by the sinking of a portion of the crest. 



Between the Escalante Hills, which is the name that has been used to 

 designate the central ridge east of the Green Eiver, and the Yampa Plateau, 

 lies a shallow, trough-like valley, through whose bottom the Yampa Eiver has 

 cut a narrow, winding caiion, which, though less deep, is proportionately nar- 

 rower, and has more nearly vertical walls than the canon of Lodore. Both of 

 these two canons, of which the one has a depth of 1,500 feet, the other of about 

 3,000, are practically inaccessible from above, and can only be explored 

 by boats, with which our parties were not provided. In Plate III, some- 

 thing of the respective character of these two canons is seen. This view^ is 

 taken from the northern wall of the Yampa Canon at its junction with the 

 Green Eiver, looking across the western end of the Yampa Valley in a 

 direction a little west of south. In the foregound, the Yampa Eiver, is seen 

 emerging from its narrow caiion into the little opening called, by Professor 

 Powell, Echo Park. In the middle distance, it joins the Green Eiver, which 

 comes in from the right, and the two rivers flow clue south for a short 

 distance into the Yampa Valley, and then doubling on their course round 

 a sharp knife-edge of rock, which cannot be distinguished, owing to the 

 correspondence of stratification-lines, from the walls of the cliff in the 

 background, flow westward to the north of this cliff, in the grander caiion 

 of the Green Eiver, called Whirlpool Caiion, whose southern wall is seen in 

 the upper right-hand corner of the view. 



To the eastward, the Escalante Hills sink gradually, and end in the 

 low valley of the Little Snake and Yampa Eivers. The course of the 

 latter river in this valley shows the same peculiarity as that of the Green 



