38 GEOLOGICAL SURVEY OF THE TEREITORIES. 



four feet in thickuess. There were three periods of effusion : first, the 

 outpouring of igneous matter over the granitoid rocks ; secondly, the de- 

 position in water of about four feet of volcanic sediment ; and thirdly, an 

 effusion of igneous matter again like tlie first. After leaving the canon, we 

 come out into an expansion of the valley, about ten miles in length and an 

 average of two to four miles in width. This area is surrounded on all 

 sides by ranges of mountains, but covered with a thickness of several 

 hundred feet of modern Tertiary beds. As exposed along the channel of 

 the streams we have at the base 50 to 80 feet of yellowish- white and creamy 

 laminated marls ; then 100 feet of cream-colored marly sandstone j and 

 overlying this an indefinite thickness of gray sandstone and puddin g-stone. 

 These modern beds jut up against the rotten granites on the south side, 

 inclining toward them about 3°. They seem to be entirely influenced 

 by the ranges on the east and north sides. The weathering is of the 

 same architectural character as the well-known " bad lands." As we 

 leave the Sweet Water and come on to the Stinking Water, the bluffs 

 of Tertiary are quite high, 80 to 100 feet, comi)osed of alternate layers 

 of sandstone and fine marl. The sandstone layers are quite hard, and 

 in the process of weathering project like shelves, giving to the verti- 

 cal bluffs a singularly rugged appearance. On the east side of the valley 

 the range of mountains is the same as .those about the sources of Black- 

 tailed Deer Greek, and are composed of limestones and quartzites of Car- 

 boniferous age. The inclination would show that this valley formed a lake 

 basin, with the granites on the west side as a shore-line, and a monoclinal 

 limestone ridge as the shore-line on the east. This valley is well 

 watered, the soil is fertile, and the grazing excellent, and already most 

 of it is occupied by farmers and stock-raisers. The elevation is 5,300 

 to 5,400 feet, and inclosed, as it is, on all sides by mountains, must be 

 protected from the extremes of cold. On the west side of the Stinking 

 Water, just above the canon, is one of the largest springs thus far 

 noticed on the route. It must have been in operation for ages, for there 

 are beds of limestone 80 to 100 feet in thickness precipitated from the 

 water. The water at this time issues out of a basin about 150 feet above 

 the Stinking Water, and covers the sides of the hills with the sediment. 

 The rock varies in texture from a compact white limestone to a soft spongy 

 mass. A snow-white efflorescence — soda, i)erhaps — covers the surface 

 in some places. The older deposits of this spring form the most beau- 

 tiful white limestone, which would be most excellent for building purposes 

 or for burning into lime. The beds dip west 10° to 20°. This is a 

 most remarkable dei)osifc, though a local one. The basis or underlying 

 rocks are quartzites and granites, inclining east 40° to 50°. Overlying 

 them, further down the stream, in the caSon, are limestones with well- 

 marked Carboniferous fossils. About five miles below the junction of 

 the Sweet Water branch with the Stinking Water, the latter stream 

 passes through a gorge or caiion, and, as we descend the streain between 

 the narrow, rugged walls, we have on the left or west side a group of 

 quartzites of various textures, which had not been observed previously. 

 They are composed of an aggregate of crystals of quartz, brown and rusty 

 drab-brown color, inclining east at a high angle. On the right or east side 

 are the overhanging projecting edges of beds of massive quartzite, rising 

 800 to 1,000 feet above the bed of the creek. The streams here pass 

 through a gorge between the ridges inclining in the same direction, which 

 I have called a monoclinal interval. We here find exposed one of the 

 remarkable series of quartzitic strata mentioned above, rising to the sum- 

 mits of the east side of the canon, huge cubic blocks of which have fallen 

 down and are strewed through the gorge. Underneath is an immense 



