20G GEOLOGICAL SURVEY OF THE TERRITORIES. 



ofteu seen, except wlien the deep snows drive tbera out of the mount- 

 ains, and the buffalo is here entirely exterminated. 



Hollows on the northern slopes, where the snow lies late in the spring, 

 and so furnishes the requisite moisture, are mostly filled with little 

 copses of scrubby coftonwood. The higher and more rocky parts of the 

 hills bear large numbers of stunted cedars, {Juniperus occidentalis.) One 

 of these was seen, a half mile east of the fort, which measured 41 inches 

 in diameter, while only 12 feet high, a form j)robably resulting from the 

 great dryness of the atmosphere. Large pines are brought from the 

 canons in the north slopes of Mount Putnam, (formerly known as Sab- 

 lett's Peak.) 



The spur which divides Iloss's Fork from Lincoln Valley seems to be 

 the final termination of the limestone ridge which formed the eastern 

 boundary of Marsh Valley and of the upper part of the lower canon of 

 the Port Neuf, and is mainly a mouocliual ridge with strong easterly 

 dips. Its culminating point is a lofty peak, now called Mount Putnam, 

 standing about twelve miles south of Fort Hall. Its western base was 

 not examined ; but it is evident that the lower quartzite forms a large 

 portion of its lower face, followed above by from 2(]0 to 300 feet of drab, 

 thin-bedded limestone, in which no fossils were seen ; then, from 100 

 to 150 feet of compact, coarse, pebbly sandstone, nearly pure white ; 

 then several hundred feet of dark drab, i>ebbly limestone, evidently of 

 Quebec Group age, though only fragmentary fossils could be found, with 

 the exception of a single Ophileta: A covered space follows, appar- 

 ently underlaid by the continuation of the last-named limestone, and 

 then comes an outcrop of about 50 feet of compact, fine-grained, white 

 sandstone, overlaid by from 200 to 300 feet of a light-drab vesicular 

 limestone, much resembling in texture the Niagara limestone of Indiana 

 and Illinois, and probably representing either the Upper Silurian or the 

 Devonian. Neither of these beds showed fossils. Immediately above 

 come heavy beds of Carboniferous limestones, 300 feet or more in thick- 

 ness. Their lowest layers include some pretty pure limestones, some of 

 which are partly oolitic and contain great numbers of minute fossils, 

 the mass looking much like the layers of the Saint Louis limestone at 

 the famous locality of Spergeu Hill, Indiana, except that the color is a 

 dark-biuisii drab. From masses collected here, over forty species of 

 brachiopods, conchifers, gasteropods, i)entremites, corals, and bryo- 

 zoans have been separated, of which Mr. Meek has already identified 

 fourteen with well-known Spergen Hill forms. Mr. Meek informs me 

 that these are the first distinctively Spergen Hill forms yet brought 

 from the Eocky Mountains. It will be remen^bered that a few allied 

 forms from Little Cottonwood Caiion, Utah, have already been men- 

 tioned in this re})ort. These beds are followed by several hundred feet 

 of very cherty limestone, rarely containing any fossils, except a large 

 Zaphrentis {Z. Stansbiiryt,) which is very abundant in some layers. The 

 upper i)art of the series consists of mostly pure limestones, from which 

 a few specimens of SpirlJ'er, Froductufi, &c., were obtained. The rocks 

 of this series form the upper part of the western face as well as the 

 summit and eastern slope of Mount Putnam. 



Passing northward along the line of this ridge we find it much eroded 

 and, in two places, cut entirely through by small tributaries of Poss's 

 Fork. In these gaps, the lower quartzites outcrop clear through the 

 ridge, while the intermediate knobs are capped with the Quebec group 

 limestone. The strike of the beds runs a little to the east of the line of 

 the ridge, so that the Carboniferous limestones pass out from the main 

 spur and form the high knob which stands, at the south end of the main 



