BIG EVANS ANTICLINE. 261 



each in White Porphyry on either side of what is supposed to be the ridge 

 of Blue Limestone connecting this anticline with South Evans anticline. 

 The Third Term (S 44) bore-hole, just across Evans gulch from the Gum- 

 ming & Finn smelter, passed through 170 feet of Wash -into the Lower 

 Quartzite, in which it found a small body of White Porphyry, supposed to 

 be the same as that already mentioned as found in the Lida (S-52) shaft, 

 on the other side of the anticline. The outcrop of Archean indicated on 

 the map has not been proved by any shaft, but is simply a theoretical de- 

 duction from the dip of the beds, the rock surface being buried beneath one 

 to two hundred feet of Wash. On the southwest slope of this anticline the 

 Mystic and Silver Pilot (R-8) have been sunk a short distance in the over- 

 lying Gray Porphyry. The Oolite (S-57) shaft passed through 100 feet 

 of Gray Porphyry and 15 feet of White Porphyry, reaching a considerable 

 body of vein material and chert, in which were found fossils characteristic 

 of the Blue Limestone horizon. The Sequa shaft (S-58), about eleven 

 hundred feet west of this, reached a depth of 280 feet, still in Gray Porphyry, 

 showing that the actual contact must be at a still greater depth, and thus 

 proving the southwestern dip on this side of the anticline and a synclinal 

 fold to the west. 



AREA WEST OF CARBONATE AND FRYER HILLS. 



General structure. From the foot of Carbonate and Fryer Hills extends a 

 broad, flat, mesa-like ridge, sloping at a regular angle of about two and a 

 half degrees to the Arkansas Valley. This even surface is doubtless con- 

 formable with the surface of the stratified Lake beds which underlie it, over 

 which rearranged moraine material or Wash has been spread out with com- 

 parative uniformity by the action of water. The relics of the moraines 

 which were left by the Big Evans glacier are found in the ridge which ex- 

 tends from the west end of Fryer Hill to Capitol Hill ; also, in James Ridge, 

 adjoining the mouth of Big Evans gulch, and in a smaller ridge between 

 the two, below North Leadville. No shaft has yet reached the rock sur- 

 face beneath these recent accumulations of detrital material. The outcrops 

 indicated on the map, and the basin character of the area, as shown in cross- 

 sections, are therefore, in one sense, purely theoretical. As they have been 

 determined, however, after a careful consideration of all the known facts 



