8T.J0IIX.] TETON RANGE. 417 



to right and left, fomiing a prominent course in tlie walls of the amphi- 

 theatres into which this part of the range has been sculptured. A frag- 

 ment of the Niagara still crowns the crest of the huge ridge between the 

 upper main forks of the stream. About midway of the valley-course of 

 the stream, the Quebec limestones appear to view from beneath the Niag- 

 ara, and gradually rising to the east, at the upper end of the valley they 

 show in two fine escarpments separated by a band of steep talus over an 

 interdeposit of blue clay and shales, the whole making up a thickness of 200 

 to 400 feet. A similar talus slope constitutes the demarkation between the 

 upper ledge of the Quebec and the Niagara. The slope below the Que- 

 bec is broken here and there by outcropping ledges of white sandstone 

 and quartzite conglomerate, probably interstratihed with softer deposits 

 above, which make up the lower 200 feet of the sedimentary deposits. 

 The quartzites rest upon the unconformable Archajan, which latter sinks 

 beneath the valley level a short distance below the mouth of Jac-kson's 

 Canon. The Quebec limestones and underlying quartzites mount high 

 on the ridge intervening between Jackson's (Jauon and tlie Teton Canon, 

 and suddenly terminate in the cap of the Pulpit, which immediately over- 

 looks the head of the grand canon of East Teton Creek. Beyond this 

 the Archnean rises up into the culminating peaks of the range, occupying 

 a belt about five miles in width extending to the eastern foot of the 

 range. 



At the forks of the West Teton Valley the Carboniferous limestones have 

 reached a relative elevation of 2,G00 feet, where, in the heights in the south 

 angle, 1,000 to 1,500 feet of the inferior portion of the series are seen in 

 successive ledges and hidden bands, underlaid by the Niagara, Quebec, 

 and quartzite, which here exhibit one of their finest exposures. It was 

 in this vicinity Professor Bradley prosecuted his examinations, an inter- 

 esting accoimt of which is incorporated in the report for 1872. At that 

 time Professor Bratlley inferred from their relative iiosition, and i^artly 

 on account of lithological resemblances, the Niagara age of the buff-gray 

 magnesian limestone, which presents one of the most i>romineut features 

 in the magnificent exposure of this locality. As previously mentioned, 

 it was our fortune to confirm this identification by palfeontological evi- 

 dence found in connection with this horizon in the northern i>art of tlie 

 range. In 1872, Professor Bradley obtained from the inferior drab thin- 

 bedded limestones a few fragments of trilobites, representing species of 

 the genera Conocoryphc and DicellocepkaJus, from which he Avas able to 

 establish the Quebec age of these lower limestones. He found the Que- 

 bec underlaid by compact and shaly glauconitic sandstones, which in turn 

 rest upon a bed of ferruginous (piartzite, 50 to 75 feet, the whole estimated 

 at about 350 feet locally, and which were respectively comi)ared to the- 

 Knox sandstones of Tennessee and the widely distributed Potsdam. In 

 the lack of facts in the least controverting Professor Bradley's determi- 

 nations of the strati graphic equivalents of the above formations, the 

 names which he applied to them have been accepted, only habitually re- 

 ferring to the arenaceous inferior deposits, both sandstones and quart- 

 zites, under the term Potsdam, or simjily quartzite. During the brief 

 time we spent in the vicinity, the lower or Quebec limestones were found 

 to form two distinct horizons, separated by a deposit of blue clay and 

 shalv lavers, the up^jer bed the thickest, and together making a thickness 

 of 200 to 400 feet. 



A se(;tion in the south side of the West T6ton Valley to the forks, thence 



passing over the partially Quebec-cappe'd ridge between the north branch 



and Jackson's Canon to the Pulpit, and thence by Mount Hayden to the 



eastern foot of the range, along a nearly east- west line, is shown in the 



27 G S 



