U4: 



TRANSACTIONS OF THE 



[JAN. 18, 



perpendicular a thousand feet and more, wliile at their base lies 

 a talus of 500 feet at an angle of 45°. The canon of the Animas 

 reaches to the foot of Engineer Mt. 



Here we begin the descent of the Uncompahgre river. It cuts 

 the west foot of Engineer cleanly and boldly, making a natural 

 section of it for moi-e than twelve miles. 



Engineer is 13,791 feet above tide. Here porphyry and tra- 

 chyte rest upon upturned edges of altered stratitied rock, and the 

 line of contact can be easily seen, and the thickness of the over- 

 flow ascertained. It is some 3,000 feet or more. From the 

 summit down to Ouray is 5,331 feet. We can fall this distance 

 in about eight miles travel; more than half of it is through erup- 

 tive rock. 



Fig. 2.— Section of Mts. at Silver Link Mine. 



A. Altered rock, Quartzite; /", Porphyry, conglomeritic, blue, purple and brecciated ; 

 R, Uncompahgre river. 



From a station opposite Silver Link mine, looking east, we 

 see the altered stratified beds standing at a high angle, with 

 northern dip, and rising in cliffs from the lowest depths of the 

 caflon, 2,000 feet, and then 3,000 feet of eruptive rock piled on 

 their summits. The ridges of stratified rock are sharp and well 

 defined, the valleys narrow and not very deep. Here we have 

 the evidence that the 8an Juan Mts. existed anterior to the out- 

 flow and overflow of igneous rock. We can see where stratified 

 beds took an upward bend to form lied Abram Mt. 



A section from summit of Engineer Mt. along the old Lake 



