ELKHEAD MOUNTAINS. 175 



its bed marking approximately the line of contact between the volcanic and 

 Archaean rocks. Below the meadows, it runs for a short distance in a deep 

 rocky canon, which opens out into a broad valley largely covered with 

 recent detrital material. To the east of this valley rise the densely-wooded 

 spurs of the Park Range. Its western slopes are covered by the gently- 

 inclined trachyte flows of Steves Ridge. In the deeper cuts, made by streams 

 flowing from this ridge, are disclosed a few indistinct outcrops of fine-grained, 

 gray, calcareous sandstones, containing minute black grains like magnetite, 

 which are evidently of Cretaceous age, but afford no clue to the horizon they 

 occupy in that formation. Some remnants are also found of a light-gray 

 trachytic tuif, enclosing fragments both of trachyte and of Archaean gneiss. 



Toward the northern end of Steves Ridge, a red, striped hornbleildic 

 gneiss, which has already been described, is found directly underlying the 

 benches of the more basic trachytes already mentioned. The same 

 red gneiss, enclosed in beds of dark-green hornblendic gneiss, is found 

 exposed at the north base of Camel Peak, just below the bend of the 

 river. It here forms a little rocky knoll overhanging the south bank of 

 the stream, and to the north passes under the horizontal beds of soft 

 sandy and clayey material, forming the plateau country to the north. Its 

 strike is here north 30° west, with a dip of 45° to the southwest. A con- 

 tinuation of this outlying portion of the Archaean body is found at the forks 

 of Battle Creek, where the beds form the face of the included spur, having 

 a nearly east and west strike, with a dip of 45° to the south. 



On the low dividing ridge between the head of Slater's and of Steves 

 Fork, and in a narrow gap at the mouth of the fatter stream, is found a 

 trachyte of somewhat distinct mineralogical character from those previously 

 described, which, from its position, as well as from the external habit of the 

 rock, would seem to represent an older eruption, or at least one which 

 cooled at a greater depth below the surface. At the mouth of Slater's Fork, 

 it forms a narrow ledge, only exposed by the deeper cuts of the stream-bed, 

 and is capped by friable white sandstones, themselves in turn covered by 

 flows of basalt. It is a reddish or greenish-gray, compact rock, having at 

 times almost the texture of an older diorite or porphyry, which, in a crypto- 

 crystalline felsitic groundmass, shows an unusual development of brown 



