HOLMES.] THE EAST GALLATIN MOUNTAINS. 23 



end is flat or undulating and is covered by a dense pine forest. There 

 are no exposures of rock iintil we rise above the general level of the 

 plateau and encounter the granite. Alluvial drift, with probably more 

 or less glacial drift, covers a large area all around the east and south 

 bases. 



On the morning of the 8th Mr. Gannett and I set out to ascend the 

 southern summit of the range, which is only inferior in elevation to 

 Electric Peak, being 10,100 feet in height. This peak, or what we sup- 

 pose to be this peak, has been spoken of occasionally by visitors as 

 Mount Madison, but on what authority or for what reason it is not 

 known. Mr. Gannett having first ascended it and determined its height 

 and geographic position, proposed to give it the name of the writer, 

 and by that name it will appear on his maps. 



At an elevation of 8,000 feet we emerged from the forest and came 

 out into a parked zone that skirts the lower slopes. Here there are 

 fine upland pastures to which the wild game of the country resorts. 

 Herds of elk were frequently encountered, and the country is literally 

 cut up by their trails. At an elevation of 8,700 feet we reached an out- 

 crop of reddish feldspathic granite. This rock is very compact and 

 massive, and forms a low rounded bench which may be traced around 

 the base of the mountain, and which on the map will give a crescent- 

 shaped area, circling the south base and- separating the Silurian rocks 

 of the range above from the drift zone that occupies the immediate 

 base. Eesting on the granite is a bed of about 200 feet in thickness of 

 hornblendic trachyte, which has been intruded as a broad sheet be- 

 tween the granite and Paleozoic strata above. The ascent of a very 

 steep declivity of some 500 feet brought us to the point of a narrow 

 fiat-topped promontory projecting to the southeast from the main peak. 

 In the steep face of the promontory there are some 300 or 400 feet of 

 dark gray laminated but much indurated limestones. They contain no 

 recognizable fossils. These limestones form a well-marked escarpment 

 that exends around the base of the range, sinking with a dip of 2° to 5^ 

 to the level of the drift plain on the south slope. 



From the promontory we passed up over heavy snow fields and up a 

 sharxD crest, and at an elevation of 10,200 feet reached a sharj) conical 

 point, a southeast outlier of Mount Holmes. Between this point and 

 the main summit there is a depression of a few hundred feet. The ex- 

 posed strata are limestones, siliceous limestones, and quartzites, with a 

 few seams of indurated trachyte. Between the granites and the summit 

 the rocks exposed have a thickness of upwards of 1,500 feet. In the 

 middle part of the section there is a pretty heavy series of fossiliferous 

 limestones, from which I obtained two species of Orthis, Reliolites {?), 

 Lingulepis, and Trilobites, the two latter occurring in great numbers. 

 Good specimens are hard to obtain on account of the very firm texture 

 of the rock. 



There are occasionally beds of dark fetid limestone, and throughout 

 the whole series more or less calcite in pockets. That the formations 

 exposed in this mountain are chiefly Silurian is proved by the fossil re- 

 mains, and that they are probably all of this age, from the granite to 

 the summit of Mount Holmes, seems probable from the very uniform 

 character of the strata. 



The day being exceedingly cold I had to refrain from prolonged exam- 

 ination as well as from the usual sketching. Topographically the peak 

 is simple, but scenically rather imposing, occupying, as it does, the ex- 

 treme i)oint of the range and overlooking a grand sweep of low country 

 bordering the Madison. The sides of the mountain are comparatively 



