GEOLOGICAL SURVEY OF THE TERRITORIES. 37 



bedding wliich may be called shelving, or a splitting into layers of greater 

 or less thickness, depending on the compactness of the material. Some- 

 times the modern basalt caps the qaartzites, of which we have several 

 exami)les on our way to the main valley of the Stinking Water. Still 

 farther down we find a branch of the Stinking Water called Sweet 

 Water, cutting directly through a mass of variegated porphyries, like 

 those in Wild Oat Canon, forming the Sweet Water Canon. The great 

 variety of colors which these rocks present, the height and abruptness 

 of the walls, and the style of weathering on the summits, give to the 

 scenery in this region a weird kind of grandeur and beauty. At the 

 base of the walls is a vast quantity of debris, composed of the frag- 

 ments of porphyry. The sides of the porphyritic walls show a regular 

 bedding like strata, in layers from an inch to a foot or more in thickness. 

 At the lower end of the canon, the gneissic beds appear beneath the por- 

 phyries, showing the character of their connection admirably. The 

 former rest upon the upturned edges of the quartzites, asifthey hadbeen 

 poured out in a fluid condition, filling up all the irregularities of the 

 surface. 



The geological character of this immediate region may be expressed 

 simply as very modern basalt, capping rocks of different ages, A^hich 

 may be in the vicinity of the point of effusion. We then have a group 

 of modern Tertiary beds, probably Pliocene, filling up the valleys and 

 irregularities of the surface everywhere, except on the summits of the 

 highest mountains. During the latter portion of the Tertiary age, the 

 entire northwest seems to have been a fresh-water lake, with vast 

 numbers of mountain elevations occupying a greater or less area, not 

 unlike some of our inland lakes at the present time, on a small scale, 

 with the more elevated points and mountain ranges rising above the 

 surrounding waters. These modern deposits have been elevated also to 

 a certain extent, as there is in many instances an inclination of the 

 strata from 1° to 5^. These cover the porphyries which were effused at 

 a period far back in the past, subsequent to the deposition of the former 

 rocks described, but hov>^ much further back into the past I found no 

 evidence to determine. I have as yet been able to find the porphy- 

 ries only in connection with the gneissic rocks. The forces which 

 operated to lift the gneissic rocks must have acted long prior to those 

 great elevatory movements which affected the sedimentary strata, and 

 although the porphyries seemed to have flowed out over the gneiss 

 since the strata have been elevated to their present position, it is noc 

 possible for me to give the x)recise geological period w^hen these events 

 occurred. Usually either lower Silurian sandstone or Carbouiferous 

 limestone rests upon the metamorphic rocks. In a few instances the 

 inclination of the Paleozoic beds above conform wath the granite 

 rocks below in such a way that I have been led to believe it possible 

 that the dynamic movements that affected both groups were synchronous. 

 But in most instances there is a greater or less want of conformity 

 between the metamorphic rocks below and the sedimentary beds of 

 any age that may rest upon them. The next group of rocks is com- 

 posed of stratified gneiss of every possible texture and composition, 

 from the most durable compact feldspathic quartzite to rotten micaceous 

 schist, warped and folded in everyway. After passing down the Sweet 

 Water CaGon about five miles, we come out into an oi)en valley, or a 

 sort of expansion. Tiie porphyries, which were previously horizontal in 

 their position, here show a dip of 20^, and about midway in the wall-like 

 front there is an apparent di\'ision by a bed of volcanic sandstones about 



