HOLMES.] GEOLOGY OF MOUNT EVARTS. 9 



a series of ridges, or hog-backs, which include a duplicate set of strata 

 produced by the foldiug back on themselves of the Upper Cretaceous 

 and Post-Cretaceous (?) rocks. (See Section F.) These strata are so ob- 

 scured by soil and vegetation that one can neither determine their exact 

 character nor say just where the axis of the fold runs. As the distance 

 is upward of three miles, aud the dip mostly quite steep, the series of 

 strata must be very large. This apparent thickness of strata makes it 

 seem probable that they comprise, besides the Middle and Upper Creta- 

 ceous, at least a part of the Post- Cretaceous or Laramie Group. 



On the eastern slope of Mount Evarts and in the valley of Black- 

 tail-deer Creek I did not observe any outcrops of the sedimentary 

 rocks, local drift and flows of lava covering everything up, but on the 

 east side of the latter valley the sedimentary rocks rise above the cover- 

 ing of lava in two or more small ridges. As will be seen by reference 

 to the map, these are nearly on the line of the fault and probably be- 

 long to the dragged strata of the south side. They are Carboniferous 

 sandstones, aud contain numerous characteristic fossils, amongst which 

 the following genera are represented: Spirifer, Athyrus, Memipronites, 

 and Prodiictus. 



On the trail near the head of the eastern branch of Black-tail-deer 

 Creek some sandstones occur which have also a vertical position, and a 

 strike almost uniform with that of the more westerly outcrojjs. East of 

 this, so far as my knowledge goes, there are no exposures of the rocks 

 of the south side of the fault. The schists .of the north side form the 

 walls of the third caiion and appear in Junction Valley and in the lower 

 part of the valley of East Fork. 



MOUNT EVARTS. 



In the angle between Gardiner Eiver and the Yellowstone is a broad 

 triangular mountain mass comprising an area of about 20 square miles, 

 which is known by people who frequent the Park as Mount Evarts. 

 This name has been attached to it since 1870. The story of Mr. Evarts' 

 adventures and suffering is well known, and the fact that his rescue 

 from a horrible death took place in a little valley just back of the sum- 

 mit of this mountain makes the name more than usually appropriate. 



To the casual observer this mountain may not seem to be one to which 

 he would be ambitious to attach his name; but I am free to say that as 

 an object of interest, either to the tourist or geologist, it has not its equal 

 in the Park, and I am quite sure that those who come once within its 

 shadow will not soon cease to remember it as one of the most striking 

 landmarks of the whole land of wonders. 



The visitor to the springs is constantly confronted by a gigantic 

 mountain wall that rises on the opposite side of Gardiner Eiver to the 

 height of 2,000 feet, and seems to close him in in a way that is almost 

 oppressive. In the morning light and up to midday this wall is in 

 shadow, and is almost a blank, but as soon as the sun reaches the 

 zenith the ridges of its deeply scored face begin to appear in relief, and 

 we have a chance to study the character of the formations aud the very 

 striking work of the erosive agents. 



From the high angular point that overlooks the junction of the East 

 Fork with the main Gardiner a broad, massive sheet of rhyolitic lava 

 extends back to the right and left across the i)lateau-like summit. 

 Fi'onting the springs this cap of rhyolite breaks off in a vertical wall 

 nearly 100 feet in height. Just opposite the springs, at the highest point 

 of the mountain, the wall terminates rather abrui)tly, the lower surface 



