38 EEPORT UNITED STATES GEOLOGICAL SURVEY. 



falls, the river makes a bend, first to the east aud then a little farther 

 on, to the north, and sooa afterwards into its course to the northeast. 

 Erom the promontory, which overlooks the bend, we have a very good 

 view down the canon. (See Plate XVIII). The walls on both sides are 

 broken down a good deal, and are partially covered with forest. There 

 is much brilliant color in this part of the caiion, owing to the presence 

 of hot springs, which seem to occur in considerable numbers on the 

 slopes, more especially near the bottom on the west side. To the left, 

 beyond, we have the profile of the eastern end of the Washburn Eange, 

 with Mount Washburn at the left. About two miles below the point of 

 observation, and near the base of the Washburn Eidge, there is an es- 

 carpment of stratified rocks, which is apparently formed of volcanic 

 conglomerates. Whether these beds are underlaid by the rhyolite 

 rocks of the plateau, or by the fraginental materials that constitute the 

 core of Mount Washburn, I am quite unable to say. It was quite use- 

 less for me to go farther in the heavy storms, as nothing couhl be seen 

 with clearness beyond a very short distance, so I turned back and crossed 

 to Cascade Creek, passing around the base of the foothills of Mount 

 Washburn. The formations, wherever exposed, are of the rhyolites and 

 obsidian porphyries of the plateau. Late in the evening I found camp at 

 the summit of Washburn Pass. 



On the 29th of September I made another attempt to follow the brink 

 of the caiion from the falls to Tower Creek, but failed, the continuous 

 snow-storms making such a feat impracticable. We broke camp at the 

 mud geysers early in the morning. I had an opportunity of making 

 some examinations at Crater Hill and at the falls, and had reached Sul- 

 phur Creek at the point of its descent into the canon, when it became 

 evident that the storm would continue throughout the day and night, 

 and I sought camp at the head of the Cascade Creek meadows. The 

 snow in places was already a foot deep. On the following day we 

 crossed the range, and were delighted to find that the valley of the 

 Yellowstone was almost clear of snow. On reaching the crest of the 

 spur, which extends from Washburn down towards Tower Falls, I 

 turned to the right across the base of the conglomerate spurs that lie 

 between the branches of Antelope Creek, and reached the brink of the 

 caiion at a point nearly opposite Jasper Creek. The caiion is here quite 

 narrow and the walls steep, although not so precipitous as to prevent 

 the growth of pine forest. The caiion of Jasper Creek is also very nar- 

 row, and the geologic formations are finely exposed in its steep walls. 

 All that can be seen of the creek is a white, thread-like cascade leaping 

 over the rocks into the river. To the left of Jasper Creek, and about 

 half a mile below, is the mouth of the caiion of Agate Creek; and just 

 beyond that is the naked wall which I examined while engaged in the 

 study of Amethyst Mountain. I had some difficulty in finding a place 

 to descend the caiion wall, but finally struck a broken spur (</, Plate 

 XIX) that seemed to extend doAvn to the river without vertical cliffs. 

 In the spurs to my right and left were fine exposures of the geologic 

 formations. Four hundred feet of the upper part consists of the ordi- 

 nary gray and mottled rhyolite. Toward the top it is somewhat decom- 

 posed, and weathers down in heavy, rounded masses. Below come 

 about 40 feet of yellowish, coarse-grained rhyolite with a rude columnar 

 structure. The surfaces of the columns are rounded off' by decomposition, 

 and the tops are weathered into rudely conical points. Below this a,re 

 about 100 feet of yellowish columnar trachyte, forming a fine vertical 

 cliff. Toward the top the columns, which are generally pentagonal, 

 are from 2 to 6 feet in diameter, but towards the base there is con- 



