SOUTHERN END OF THE SNOWY RANGE. 205 



The valley of Lamar River, which terminates the range on this side, 

 is of even greater antiquity, and, as will be shown in Part I, it was 

 once the principal drainage of this entire region. Isolated patches of 

 the sedimentary rocks occur in the lower part of the valley, where denuda- 

 tion has removed their covering of volcanic breccias. Soda Butte Creek, 

 which has been assumed to represent the southeastern boundary of the 

 Snowy Range, presents one of the most impressive mountain valleys to be 

 found within the limits of the Park. The illustration (PI. XXVI) of 

 Baronet Peak shows the general character of this valley and the rugged 

 aspect of the high peaks which tower above it on either side. Farther up 

 the stream, at the confluence of Pebble Creek, the sedimentary rocks occur 

 in the valley bottom. Above this, in the upper valley near the mining 

 settlement of Cook City, the valley walls present bold limestone cliffs, over 

 which numerous streams, draining the higher volcanic slopes, fall in a 

 succession of cascades that are of great beauty. The white cliffs of sedi- 

 mentary rocks stand out in bold relief from the somber volcanic slopes, and 

 their steep walls, presenting an unbroken cliff often extending for miles 

 along the sides of the valley, offer few opportunities of asceut. 



SEDIMENTARY ROCKS. 



Any attempt to describe the sedimentary rocks of that small portion of 

 the Snowy Range found within the limits of the Park must be at best a 

 fragmentary sketch of the Snowy Range itself. Of the sedimentary series, 

 only the Paleozoic rocks occur within the limits of this area, nor do these 

 rocks present any very marked differences from those of the same ao-e 

 occurring in the other ranges of the region. The lowest beds exposed are 

 those of the Flathead formation. Above these the Gallatin limestones, 

 which are, within this region, so frequently seen in long lines of cliffs, are 

 well exposed and cover considerable areas. The Silurian, known within 

 this region as the Jefferson formation, presents the best differentiation of 

 this horizon found within the limits of the Park. Above these shallow- 

 water deposits are the massive limestones and thinly bedded shales of the 

 Three Forks formation, in which Devonian fossils have been found. The 

 highest sedimentary rocks which occur within this region are those of 

 the Madison limestone. 



