GEOLOGICAL SUEVEY OF THE TEKEITOKIES. 17 



head of it is located the celebrated Emma Mine. The walls on either 

 side rise to the height of 200 to 300 feet. We have at the base the 

 beautiful gray massive syenite, which is employed in the coustructiou of 

 the Mormon Temple, and resembles our best Quincy granite. Upon 

 this rests a series of feldspathic gneissic strata, and upon these were 

 deposited the lower quartzites uuconformably. The dip of the gneiss is 

 south or southeast, while the quartzites incline north or east of north. 

 The order of superposition is most clearly shown by these wonderful 

 gorges. But as examples of erosion they excite wonder. 



The evidence of drift or glacial action is everywhere seen on a 

 grand scale. The sides of the caiions are worn and furrowed by the 

 masses of snow and ice that have slidden down for centuries. The 

 waters gathering and freezing in the fissures on the sides and margins 

 of the caiions pry off, as it were, immense masses of rock, which fall 

 down into the valley below. Masses, 50 to 100 feet in diameter, block 

 up the pathway. ]!S[ear the entrance of the caiion from the valley the 

 amount of drift-material which has been swept down from above is pro- 

 digious, showing the results of forces not now in operation. As we pass 

 along the west side of the range, we shall lind a vast thickness of the 

 sedimentary rocks, ranging through the Silurian, Carboniferous, Triassic, 

 Jurassic, and Tertiary, inclining from the mountains toward the plains, 

 showing the original anticlinal structure of the entire range. 



In City Creek CaGou, just in the rear of Salt Lake City, we find near 

 the head, all the older rocks, up to the Jurassic inclusive, standing nearly 

 A'ertical, or inclining at a high angle, with the conglomerates of the 

 Wahsatch group, jutting against the Jurassic beds, also inclining at a 

 moderate angle. I have never yet observed any rocks on the west side 

 of the Wahsatch Eange filling up the interval between the Jurassic 

 limestone and the Wahsatch conglomerates. We know, however, that 

 south of Utah Lake, the interval is filled up more or less by the coal- 

 group, which seems to be, from the evidence of the fossils, the same as 

 that so well shown at Coalville on the east side of the Wahsatch. We 

 see by this fact that the conglomerates, although not conspicuous at 

 the present time, on the east side of the valley, did, ho\vever, extend over 

 the range into the valley, and may, for aught we know at the present 

 time, extend far across the valley, for they are shown with a great thick- 

 ness on the west side from City Creek Caiion for several miles to the 

 northward. 



From among the Tertiary clays and conglomerates north of the city 

 near the Hot Springs and above, the dark steel-gray limestones of the 

 Carboniferous period crop out in numerous places. About ten miles 

 north_of Salt Lake City all this immense mass of sedimentary beds, at 

 least 10,000 feet in thickness, has been swept away, leaving the gneissic 

 nucleus bare with the modei^n drift which underlies the terrace jutting 

 against the sides. From Farmington to Vfeber Canon, a distance of 

 about twenty-five miles, the beds of the little streams which flow in 

 gi-eat numbers and carve out deep caiions in the sides of the mountains, 

 furnish no trace of any unchanged rocks. 



Standing upon some high point and casting the eye northward along 

 the range, the very granitoid nucleus would appear to have been worn 

 away, and the east side of the anticlinal to appear with the upturned 

 edges of the strata cropping out -toward the valley near Ogden. This 

 monoclinal condition of the range continues northward beyond Corinne, 

 and in the intervals are some very fine exhibitions of the strata. Here 

 and there the granitic rocks appear from beneath the quartzites, Ixit not 

 continuously. If we take the position that this wonderfully picturesque 

 2 G- s 



