8 REPORT UNITED STATES GEOLOGICAL SURVEY. 



the hard metamorphic quartzites and quartzitic schists, the affinities of 

 "which puzzle me very much. It is not at all improbable that they con- 

 sist cliieHy of altered and distorted Paleozoic or even Mesozoic strata. 

 With the exception, however, of a few fragments, which are shown at * 

 in Section E, there is but slight resemblance to these formations. 



The river for a short distance above Bear Creek passes over a very 

 rough bed of dark-gray quartzites, and the water has worn deep holes 

 in the bottom and sides. Near by, on the south side, a rugged crag 

 rises from the river bank, on which an eagle has built its nest. From 

 this point, as far up as the mouth of Hell lioaring Creek, the river flows 

 over a bed of granitic rocks. 



The bluffs on the north side of the river, both east and west of Bear 

 Creek, are capped by horizontal beds of basalt, as shown in Section D. 

 These are probably remnants of sheets which once covered a great part 

 of the valley below. 



Below the mouth of Gardiner Eiver, on the south side of the Yellow- 

 stone, we have a series of vertical strata that run almost parallel with 

 the river. Such of these strata as appear above the deposits of drift 

 material are sandstones, which have a greenish color, and resemble very 

 much some of the Tertiary strata of Amethyst Mountain. At one 

 locality near the road, and perhaps a mile below Gardiner's River, I ob- 

 tained a few impressions of leaves which are considered by Professor 

 Lesquereux to indicate the Cretaceous age of the beds. This same 

 series of strata crosses the course of Gardiner River near its mouth 

 and continues along the south side of the fault-line to the valley of 

 Black-tail-deer Creek. The outcrop in a little butte that lies just above 

 the confluence of Gardiner River and the Yellowstone, and at a number 

 of points tarther up has always a vertical position. 



In tracing the displacement eastward from the mouth of Bear Creek 

 we find that a high ridge of metamorphic rock interposes itself between 

 the line of the fault and the caiiou. This ridge is broken in two or 

 three places by transverse drainage, but may be followed as far as the 

 mouth of Black-tail-deer Creek. It is com))osed principally of schists 

 that have a decided quartzitic character, and evidently belong to the 

 same series as the similar formations no' iced at the mouth of Bear Creek. 

 The general appearance of the ridge indicates a stratitied character par- 

 allel with the fold. The schists north of the riv^er are, however, discon- 

 nected with the fold, as they have a strike to the north with a steep 

 easterly dip. 



Along the depression west of the ridge of quartzitic schists just men- 

 tioned the Cretaceous and possibly part of the Post-Cretaceous strata 

 are folded back upon the strata that form the north slope of Mount 

 Evarts. At a few points rising against the schistose ridge there are 

 outcrops of gnarled limestones that are probably Paleozoic. They have 

 doubtless been dragged up in the f<iult. 



Farther on to the east we come upon a group of high, reddish hills 

 which overlook the canon to the north and Black-tail-deer Creek to 

 the east. In the southern faces of these hills the characteristic Meso- 

 zoic Red Beds appear, and the Jurassic and Lower Cretaceous forma- 

 tions outcrop along the south base. All of these formations are. vertical, 

 or nearly so. The strike makes an abrupt turn to the north around the 

 southeastern base of the hills, but soon returns to a southeasterly direc- 

 tion. Forming the summits of some of the higher points of the hills are 

 outcrops of metamorphosed and distorted strata that have evidently' 

 been involved in the fault. 



Between these hills and the highest part of Mount Evarts there are 



