328 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



gap or break appearing in this section. Near the south end of the 

 canyon the beds of the west wall are repeated by local faulting, while 

 those on the cast side show considerable crumpling and pass beneath 

 the Devonian and Carboniferous limestones that form the two arches at 

 the south end of the Avail. The general section may he briefly summar- 

 ized as follows: 



Feet. 



Carboniferous.. . 2 Quartzites and interbedded limestones ;$00 



(Limestones .> () ,w> 



Devonian Limestones and shales ""' ~' ;{0() 



( Limestones with interbedded shales flfwi 



< iambrian ) shales ]\[ Eg 



f Quartzite '.'.'.'..'.'.'.'...'.'.'.['. 100 



Emerging from the canyon these Paleozoic limestones maybe seen 

 resting at steep angles upon the gneisses and schists to the east, the 

 valley of Deep Creek having been cut along the contact. The roof-like 

 surfaces of the limestones and the square-cut bluffs and walls show in 

 Strong contrast to the spires and uniform slopes of the schists. The 

 immediate valley bottom shows a couple of hills of Paleozoic limestone 

 rising above the alluvial -ravels. To the west the faulted anticlinal of 

 Canyon Mountain brings the schists into view, but the nearer hill 

 slopes are formed of Cambrian limestones replaced farther south by 

 Devonian and Carboniferous beds, which an overthrust fault has super- 

 imposed npon the sandstones of Jurassic and Dakota Cretaceous 

 Near Brisbin an east and west ridge is formed of an anticline of Car- 

 boniferous limestones, the Mesozoic beds on its southern side passing 



beneath the da>-k-colored volcanic breccias and agglomerates that form 

 Antelope Jiutte. From here southward the sedimentary formations are 

 not seen until Cinnabar Mountain is reached near the railroad terminus. 

 The valley entered presents the most imposing scenery yet encoun- 

 tered; inclosed between the serrated crests of the Snowy Mountains 

 upon the east and the more distant peaks of the Callatin range upon 

 the west, it stretches southward some 30 miles to the Arclncan 

 gorge of Yankee Jim canyon. Eroded along the line of a -.rat fault 

 the valley has Ion- been the drainage way for the waters of the moun- 

 tainous region to the south. The site of a Neocene lake whose sedi- 

 ments only remain where protected by a basaltic lava flow, it was tilled 

 by an ice sheet that Mowed northward from the great plateau of the 

 park, and its present most striking features were imposed upon it at 

 this time. As the morainal deposits of this glacier, and the sculptur- 

 ing effected by it, form a prominent part of the geologv of this region 

 a somewhat full account is given of the glaciation of the Valley at the 

 end of this chapter. 



West of the valley the peaks of the Gallatin range rise above retreat- 

 ing slopes, dotted with groves of pines and trenched by deep and 

 narrow gorges. The range is eroded in a great accumulation of vol- 



