126 , TRANSACTIONS OF THE [jAN. 18, 



sandstones. In the vertical fissures of limestone are found silver 

 veins, some of them quite rich. The Nigger-baby, Leadville, 

 and Pony Express are notable. Above the limestone lie 300 

 feet of sandstone, and far back from the river is seen the usual 

 capping of trachyte. (See Fig. 3.) 



Trachyte extends as far as Portland. Silver ores are found in 

 the limestone as far as the trachyte extends, and on both sides 

 of the river. 



Lithologically, tliis limestone resembles a limestone found in 

 the bluffs back of Tremble Springs; it is black in color, some- 

 what slaty and arenaceous. Fossils in the Animas hills show 

 the rock to belong to the Carboniferous age. Should simi- 

 lar fossils be found in the Uncompahgre it would prove their 

 relationship, and might lead to searching for treasures on the 

 south slope of the mountains. 



Ten miles further down the river we find coal of the Creta- 

 ceous age — probably the same as that at Durango. 



Exactly where on the east the uplift of these mountains be- 

 gins, with their wonderfully prolific veins of silver, I am not, by 

 personal observations, able to say. But we shall not be far out 

 of the way, if we begin at Lake City and proceed up Henson's 

 Creek. 



Immediately we come into blue porphyry, and in a few miles 

 reach Ulay mine, celebrated for its yield, depth, and richness. 

 Continuing uj) the creek to Capitol City and Kose's Cabin, we 

 see cliffs of por])hyry on both sides. 



Open mouths of veins are all along with us. At the Cabin we 

 turn to the right hand, and rapidly ascending soon reach the 

 Frank Hougii mine, rich in silver and copper, and then the 

 summit of Engineer Mt., or, at the Cabin we turn to the left, 

 and passing by many veins of argentiferous galena, reach 

 another summit, and the nuiin pass of the mountain. Descend- 

 ing this mountain, we come into the widest divide of the San 

 Juan gi'oup. \Yq cross it at the San Juan Chief mine and be- 

 gin on Mineral Mt. the ascent of The High Trail. 



This trail is worthy of its appellation. Across San Juan 

 County and far into San Miguel, we are never below 13,000 

 ft. above tide level, and sometimes ascend a thousand feet 

 higher. We pass by the head of the west branch of the Animas 

 and the head of Po'keepsie Gulch. 



Here lies a group of rich mines; the most celebrated is the 

 Mountain Queen. The broken slab-like masses of rock look 

 as if they could reveal their original structure, if we had 

 time to study them. We see Lake Como, like an Alpine jewel, 

 lying beneath us. Passing over and around sharp peaks of 

 trachyte, we keep our course westward around the head of 



