HENRY'S FORK BASIN. 267 



no direct superposition, and the same beds are found farther east, near Red 

 Creek, to be quite conformable. It has ah*eady been seen, however, that 

 sufficient distinct evidence has been found at other points to estabHsh this 

 unconformity. 



On the south of the Bighorn Ridge extends a low valley of Colorado 

 Cretaceous, showing occasional outcrops of yellow clays and marls, bounded 

 on the south again by a high ridge or series of ridges forming the eastern 

 continuation of the Flaming Grorge Ridge. These ridges, immediately east 

 of Green River, are steep and narrow knife-edges of rock, formed by strata 

 standing at angles of 45° to 60°, of the same geological horizons as those 

 of Flaming Gorge Ridge, and rise to a height of over 2,000 feet above the 

 valley, but become lower farther east, where the trail to Ashley Park 

 crosses them, forming simply projecting sandstone outcrops, which bound 

 the northern edge of the plateau region, through whicli Green River has 

 cut its canon from the Horseshoe Bend to Brown's Park. 



Through the greater part of this plateau region, the red sandstones and 

 quartzites of the Weber group are found, dipj^ing at angles of 10° to 15° 

 northward. After entering Flaming Gorge, as we have seen. Green River 

 turns at right angles to cut its course through the hard siliceous limestones- 

 of the Upper Coal-Measures, in a canon nearly 2,000 feet deep, and, bending 

 again upon itself, returns to the base of the cliffs of red Triassic sandstone, 

 about a mile west of the point where it had left them, as may be seen in the 

 view represented in Plate I, where, however, the river, in its return course, 

 is hidden from view by the low intervening clay ridge in the middle dis- 

 tance. The lower beds thus exposed are quite conformable with the over- 

 lying sandstones, but their angle of dip decreases somewhat as the horizon 

 descends, until, as seen above, the Weber Quartzite is found to dip only at 

 15°. After leaving the Flaming Gorge cliffs for the second time, the Green 

 River cuts again through the Upper Coal-Measure limestones, and, in the 

 Weber Quartzite, assumes a general easterly course, approximately parallel 

 to the geological axis of the range, which, opposite Ashley Park, lies a 

 little to south, at the base of the line of cliffs just north of Mount Lena. 

 At its entrance into Brown's Park, therefore, the course of Green River is 

 nearly in the actual axis, and the main elevation of the Uinta Range south 



