BIG GAME EIDGE. 189 



elevation of 9,600 feet above sea level, and is the culminating point of the 

 southern end of the ridge. Its interest lies mainly in the conglomerates, 

 which form the upper 400 feet and which rest upon the mountain in much 

 the same way as they do upon Pinyon Peak. The gravels are in every 

 way identical, and belong without doubt to the same horizon. Abrupt 

 walls of this conglomerate face east and north, offering good exposures 

 across coarse gravels with polished and crushed pebbles held firmly together 

 by sands. They rest directly upon Laramie sandstones, which dip to the 

 east at low angles, and near the base of the ridge abut unconformably 

 against Madison limestone lying along the east side of the Snake River fault. 



Isolated patches of Pinyon Peak beds, left by erosion, rest upon sand- 

 stones west of Gravel Peak. They lie at different elevations, but their 

 position may be due to a series of small parallel faults found along that side 

 of the ridge. The block of sandstone north of Gravel Peak Ridge and due 

 east of Pinyon Peak presents a northward continuation of the same Creta- 

 ceous strata. The ridge trends a few degrees east of north and west of 

 south, with beds dipping at low angles to the east. Beds typical of the 

 upper portion of the Laramie make up the entire ridge. The sandstones 

 are rustv brown in color, with numerous thin layers of ferruginous material 

 interbedded with friable white sands. Clay bands and thin, shaly, impure 

 sandstone with evidence of cross bedding characterize both slopes. 



Fragmental and imperfect plant remains lie scattered over the surface, 

 and certain strata seem to carry a considerable amount of carbonaceous 

 material. Specimens of leaves and twigs were collected, indicating a vig- 

 orous flora, but all too imperfect to permit of specific identification. Over 

 the top of the ridge are strewn smoothly polished quartzite pebbles derived 

 from the Pinyon Peak conglomerate, but no beds of the same were found 

 in place. North of the pass from Wolverine Creek to Fox Creek the ridge 

 still shows the lithological habit of the Laramie sandstones. At the north 

 end the massive white beds dip from 5° to 10° SE.; in fact, all the beds in 

 this region dip to the southeast. 



The line of demarcation between the Montana and Laramie formations 

 is drawn along the southeastern slopes of Mount Hancock, as will be seen 

 by reference to the map. 



The basal rocks of the Laramie, as thus defined, trend in a general 

 northeasterly direction. Starting at the south base of Mount Hancock, 



