106 



GEOLOGICAL SURVEY OF THE TERRITORIES. 



■vvitli carboDate of copper in lim'estones. This corresponds to tlie loca- 

 tion of the most productive silver mines in Utah. They are almost 

 situated in limestones at the heads of the canons, and the ores are ores 

 of lead containing' silver. The minerals I obtained at Ogden are the 

 following: micaceous hematite, iron pyrites, galenite, magnetite, 

 graphite, azurite, malachite, garnets, quartz, chlorite, talc, serpentine, 

 jasper, hornblende, serpentine, and calcite. 



On the 19th of June Mr. Jackson started on a photographic trip to 

 Little Cottonwood Caiion, on which trip 1 accompanied. From Ogden 

 to Salt Lake City we took the Utah Central Eailroad, which skirts the 

 edge of the mountains. The granitic rocks extend for some distance 

 below Weber Cauou, but as we near Salt Lake City the limestones form 

 the base of the mountains, near which are a number of limekilns. The 

 limestone for the kilns seemed to be taken from tlie upper layers, prob- 

 ably because the lower ones are siliceous, as at Ogden. 



The canons which cut through the Wahsatch Range near Salt Lake 

 City are as follows, in their order from north to south: Eed Butte, Emi- 

 gration, Parley's, Mill Creek, Big Cottonwood, and Little Cottonwood. 

 At the head of the latter are some of the best silver mines to be found 

 in Utah, and among them is the famous Emma mine. Leaving Salt 

 Lake City we take the State road, and after a ride of ten miles in a 

 southeasterly direction, passing between thriving farms dotted with 

 comfortable-looking houses, we turn to the left and strike across the 

 country to the mountains. Directly before us is the highest point in 

 the Wahsatch Eange, the Twin Peaks, over 12,000 feet above sea-level. 

 As we ride along we see distinctly marked on the sides of the mount- 

 ains in front of us the water-lines of the former shore of the Great 

 Salt Lake. These old shore-lines are distinctly marked on the mount- 

 ains, ou all sides of the lake, and on the islands in the lake. We pass 

 over numerous terraces and at length reach the mouth of the canon. 

 Here there are no less than seven distinct terraces, some of them, how- 

 ever, due to the action of the Cottonwood Creek. Near the mouth of the 

 caiion there are smelting- works, to which ore is brought from the mines 



at the head of the creek. Inside the 

 caiion we find ourselves between high 

 granite-walls, rising precipitously on 

 either side of the creek. The first 

 thing to attract our attention is the 

 conspicuous bedding of these gran- 

 ites. The dip is east at an angle of 

 50° to 70°. The granite is of a light- 

 gray color, composed of white feld- 

 spar, .(orthoclase,) quartz, and black 

 mica. The bottom of the canon is 

 strewn with bowlders of granite, 

 which lie scattered over it in inextri- 

 cable confusion. In many of them 

 (Fig. 25) I noticed veins of feldspar 

 of about two inches in width crossing 

 each other at right angles. Another 

 noticeable feature in these granites 

 is the occurrence of rounded pebble-like masses, of a dark color, inclosed 

 in the gray matrix. Professor Silliman, (Silliman's Journal, vol. iii,page 

 196,) referring to these, says " These granites are probably metamorphic, 

 of coglomerates, an opinion first suggested to me by Professor W. P. 

 Blake.'' As he also further states, there is a pebble like roundness in 



Fig. 25. 



BLOCK OF GRANITE WITH FELDSPATHIC SEAMS. 



