emmons.] GLENWOOD SPRINGS TO LEADVILLE. 417 



are fine-grained ochreons material, consisting largely of basic sulphate 

 of iron, containing silver and gold, which is in general not visible to 

 the naked eye, though many fine nuggets of gold have been found. 

 There is good ground for assuming that these metals have, in part at 

 least, been leached from the ore bodies of the higher horizons in 

 solutions of persulphate of iron. 66 



The mines are mostly situated near the mining town of Clinton or 

 Battle mountain, on a shoulder of the cliffs about two miles north of 

 Red Cliff station. 



Near Red Cliff the Cambrian quartzites, which have come down to 

 the valley level, are stained by iron oxides to a pinkish color. The 

 narrow gorge continues for some miles beyond Red Cliff, and the valley 

 then widens. In the more open valley two curved ridges can be dis- 

 tinguished, which are terminal moraines marking halts in the retreat 

 of a glacier which once stretched down from the base of the Mosquito 

 range, 15 miles (24 km.) to the eastward. 



The railroad ascends gradually along the southeast wall of this val- 

 ley, from which good exposures of the Paleozoic; series up to the Upper 

 Carboniferous, with sheets of intrusive porphyry, can be seen on the 

 opposite side. 



It then bends southward up a side valley in Archean gneiss to Ten- 

 nessee pass (10,400 feet — 3,170 m.) which forms part of the Continental 

 divide separating the waters of the Pacific Ocean from those flowing 

 into the Gulf of Mexico. 



It passes the summit of the pass through a long tunnel, beneath a 

 thin sheet of Cambrian quart zite which forms the summit of the pass, 

 and descends on the other side, past exposures of Cambrian quartzite 

 and Silurian limestone on the east, into the broad Pleistocene valley, 

 known as Tennessee Park, at the head of the valley of the Arkansas. 

 At the lower end of this park it bends to the eastward across the East 

 fork of the Arkansas, up whose glacial-carved gorge may be distin- 

 guished some of the high peaks of the Mosquito range in which it 

 takes its rise. It then rises over a gently sloping mesa formed of 

 glacial lake beds to the city of Lead ville, which is situated on the edge 

 of the mesa, at the base of the western spurs of the Mosquito range. 

 451 GK L>7 



