482 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



the expeditions of the survey during the season of 1872, and the collec- 

 tions from the Teton region and vicinity of Fort Hall, made by Professor 

 Bradley, afforded Mr. Meek the means of establishing this identity 

 on paleontological evidence. But in their lithological peculiarities we 

 possess an almost equally sure means of recognizing these deposits, and, 

 in the absence of fossils at many localities, it becomes of great import- 

 ance to pay close attention to the local phases under which these rocks 

 appear in remote sections of the district. They are believed to be uni- 

 formly developed as two distinct limestone deposits, which may be dis- 

 tinguished by the pro visional terms upper and loicer Quebec limestones. 



Lower Quebec limestone. — In the Mount Putnam ridge, at Station II, 

 the lower Quebec limestone, showing a thickness probably between 200 

 and 300 feet, is made up apparently of three limestone beds. The lower 

 is a dark gray, even-bedded limestone, overlaid by a rough-weathered 

 buff limestone somewhat resembling the Niagara, the upper bed showing 

 a thin-bedded, dark-gray, brecciated limestone. No fossils were found 

 in these beds. In the Teton Range, especially in the sides of West 

 Teton Creek Valley, this lower ledge shows in an exposed thickness of 

 50 feet, or more, an even thin-bedded, rusty drab impure limestone, with 

 purer dark-drab layers, traversed by calcspar seams, and containing 

 minute crystals of iron, to the presence of which is doubtless due the 

 brown-stained appearance of the rock in the extensive mural exposures 

 here and elsewhere found. In the Gros Ventre Mountains the ledge 

 exhibits much the same lithological characters above cited. But at 

 Buffalo Fork Peak, where it shows an exposed thickness of 50 to 75 feet, 

 it consists of bluish and dark-drab, brecciated, thin-bedded, rough- weath- 

 ered limestone, the lower portion brown-gray and dirty-yellow stained, 

 also destitute of fossils. It will have been observed that the horizon 

 presents marked contrasts in the eastern and southwestern areas of its 

 exposure, both as regards its lithology and the comparative duration of 

 the conditions favorable for the accumulation of its component materials, 

 which in the latter quarter allowed the deposition of a thickness of 

 calcareous sediments more than double that which obtained in the Tetons 

 and to the east. 



In the T6ton Range the intermediate or passage beds between the 

 upper and lower Quebec limestones were at no point visited revealed, 

 the slope, usually short, between the two almost invariably showing a 

 steep debris-covered talus ; as was also the case in the Gros Ventre Range. 

 But in the Buffalo Fork Peak the component strata of this horizon are 

 well displayed, presenting below yellowish areno-micaceous clays, with 

 indurated layers charged with a small orbiculoid shell and thin layers of 

 dirty-drab limestone, on ihe weathered surfaces of which are crowded the 

 fragmentary remains of Trilobites and other fossils ; among others there 

 have been identified the genera Gonocoryplie and JDicilhceplialus. The 

 upper portion of the deposit is here composed of bluish-drab shales and 

 brownish-gray shaly sandstone, the latter probably corresponding to the 

 indurated arenaceous layers with the orbiculoid shell above mentioned. 

 The deposit at this locality probably reaches a thickness of between 100 

 and 200 feet, and the fact of its satisfactory exposure is due to its posi- 

 tion in the crest of the elevated ridge culminating in Buffalo Fork Peak. 

 The supposed equivalent horizon in the Mount Putnam ridge north of 

 Ross Fork, at Station II, is occupied by a heavy ledge of conglomeritic 

 quartzite, which shows in exceedingly rough- weathered exposures 40 to 

 50 feet in vertical extent, but it is probably thicker, the space above and 

 below 7 , together with its outcrop, reaching 100 to 150 feet. The charac- 

 ter of the associated deposits immediately above and below was not as- 



