THE CRAGS. 6 



and ridges, attaining altitudes of from 10,000 to 11,000 feet above sea level, 

 with occasional plateaus, 2,000 feet or more above the valley bottom. 



The bold escarpment and barren upper portions of these mountains 

 permit their general structure to be made out with ease, even from a 

 distance. Thus the general structure of the eastern face of the range may 

 be seen from Bunsen Peak or Terrace Mountain. The open, park-like 

 character of the valleys and lower slopes of the mountains, the abundance 

 of grass and water, and the multitude of flowers that cover the whole, 

 country during the summer season render this one of the most picturesque 

 and delightful of mountain regions, both for the geologist and for the artist, 



THE CRAGS AND VICINITY. 



A description of the geological features of the Gallatin Range naturally 

 begins with an account of the region where the basal and lowest rocks of 

 the series are exposed. These occur in the southern and southwestern part 

 of the range, and a description of the range from these peaks northward is, 

 in general, also a description of successively later geological formations. 

 The oldest rocks of the region are crystalline schists, which are mainly 

 gneisses. These rocks form two prominent topographic features of the 

 southern end of the range. The first of these is the group of rugged peaks 

 called The Crags, together with their less elevated spurs to the south, and 

 their prolongation in the ridge trending northwest, parallel to Grayling 

 Creek. Crowfoot Ridge constitutes the second prominent mass of crystal- 

 line schists, while the low rounded hills at the head of Grayling Creek are 

 also formed of these rocks. A few inconspicuous outlying exposures of 

 schist occur to the southwest, where erosion has removed the overlying 

 sheet of rhyolitic lava. 



THE CRAGS. 



The rocky summits of The Crags and the ridges northwest are very 

 rno-o-ed and difficult to traverse on account of the loose de'bris and thick- 

 timbered slopes. But while the southern escarpment of Crowfoot Ridge is 

 equally obstructed, its summit is comparatively open and level topped, 

 showing little erosion since the removal of the sedimentary cover. The 

 lower hills between Grayling and Maple creeks are rounded and smoothed, 

 with every evidence of having been glaciated and considerably worn. 

 Throughout this area of crystalline schists, coarse and fine grained gneisses 



