st. johx.] TETON RANGE. 417 



to right and left, forming a prominent course in the 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 tipper 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 demarkati on between the 

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

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

 and quartzite conglomerate, probably interstratified with softer deposits 

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

 The quartzites rest upon the unconformable Archaean, which latter sinks 

 beneath the valley level a short distance below the mouth of Jackson's 

 Cation. The Quebec limestones and underlying quartzites mount high 

 on the ridge intervening between Jackson's Canon and the 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 Archaean 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 2,600 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 Magara, Quebec, 

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

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

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

 time Professor Bradley inferred from their relative position, and partly 

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

 magnesian limestone, which presents one of the most prominent 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 part of the 

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

 bedded limestones a few fragments of trilobites, representing species of 

 the genera Conocoryphe and Dicellocephalus, from which he was 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 quartzite, 50 to 75 feet, the whole estimated 

 at about 350 feet locally, and which were respectively compared 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 stratigraphic 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 simply 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 upper bed the thickest, and together making a thickness 

 of 200 to 400 feet. 



A section in the south side of the West Teton Valley to the forks, thence 



passing over the partially Quebec-capped 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 as 



