GEOLOGICAL SURVEY OF THE TERRITORIES. 97 



at any other point along the railroad from Laramie Station to Green 

 Eiver. The entire series of rocks are exposed here, from the syenites to 

 the Cretaceous, inclusive. The railroad passes through an anticlinal 

 opening. 



On the south side of the road are a series of variegated gray, brown, 

 and reddish siliceous rocks inclining southwest about 3° to lO^. Rest- 

 ing upon them is a very hard bluish limestone which is undoubtedly Car- 

 boniferous, though I was unable to find any fossils in this region. 



On the north side of the road the ridges of upheaval strike off toward 

 the northwest, rising to a height of 1,200 to 1,500 feet above the road. 

 If we examine these ridges with care we shall find that the red syenite 

 is exposed in a number of places, and we have the opportunity here of 

 studying the relations which the unchanged rock sustains to the meta- 

 morphic. 



The syenitic beds dip 70° about southeast, while the unchanged beds 

 rest upon them in nearly a horizontal position. The layers which rest 

 directly on the syenite are a beautiful pudding-stone made up of rounded 

 quartz pebbles and feldspar; above are layers of fine siliceous rock with 

 thin intercalations of clay. The whole series have the position and 

 appearance of Potsdam sandstone, and I am inclined to believe that we 

 have here a representation of the Lower Silurian period. In all cases 

 these rocks repose on the upturned edges of the syenite; sometimes 

 nearly horizontal, again inclining 5° to 10°. In one or two localities 

 these Lower Silurian beds are lifted up 1,000 feet or more, nearly horizon- 

 tally, while on the sides of the mountain the beds are broken off so as to 

 incline 50° to 60°, or nearly vertical. 



The siliceous rocks make most excellent building-stone, and are much 

 used by the railroad company. They reach a thickness of 500 to 800 

 feet. There is every variety of tidal stratification, mud workings, wave 

 and ripple marks, &c. On these siliceous beds rests the blue limestone, 

 30 to 40 feet thick, and above are variegated sandstones and the red beds 

 in the distance. 



From the tops of these ridges one can see numbers of synclinal and 

 monoclinal valleys ; I mean by monoclinal valleys the intervals between 

 upheaved ridges where the beds in each ridge dip in the same direction. 

 There is one here which stretches far to the northwest, three to five 

 miles in width, and so smoothed by erosion that it forms a level grassy 

 prairie. 



In all these upheaved ridges the rocks afford wonderful proofs of ero- 

 sion. The Silurian (?) beds exhibit the combined action of water and ice 

 in a more powerful manner than the more recent beds, even. 



Everywhere, however, the evidences of erosion during the Drift period 

 are on a gigantic scale. Some of the bed's are smoothed off as if they 

 had been planed ; others are furrowed. 



There is a fine sulphur spring here which gives the name to the station. 

 The water issues from under the bed of blue limestone. The water is 

 clear and possesses medicinal properties. 



About four miles west of Eawling's Springs the Tertiary beds begin to 

 overlap ; but in the distance, on either side, are lofty ridges which are 

 composed of Cretaceous, and perhaps rocks of even older date. 



South of Separation, 15 miles, there is a ridge that is at least 1,000 

 feet high, which is certainly formed of Lower Cretaceous, and probably 

 also of that great thickness of sandstones and clays which holds a posi- 

 tion between the transition beds Ko. 1 (?) and the brick-red beds. 



IS'ear Separation, about ten miles west of Eawling's Springs, a coal 

 mine has been opened with a bed of coal 11 feet in thickness. I am in- 

 7 H 



