128 Hillebrand and JRansome — Carnotite and Associated 



The most remarkable and interesting fact in regard to the 

 La Sal Creek deposits is their very superficial character. The 

 ore bodies are usually flat-lying streaks, a few inches thick, 

 which grade above and below into the common light-buff sand- 

 stone, and which die out and disappear when followed into the 

 hillside. In tunnels run but a few feet underground the yel- 

 low impregnation of carnotite can be seen to gradually die out, 

 to be succeeded by light-colored sandstone, snowing no appar- 

 ent trace of the mineral. It is doubtful whether any appre- 

 ciable quantity of carnotite occurs as much as 20 feet from the 

 surface, on any of the locations, although this distance is given 

 from memory and not from measurements on the ground. As 

 before stated, the impregnation has usually taken place along 

 bedding planes ; it has also proceeded along surfaces of minor 

 and superficial movement in the rocks. In one case it was 

 observed that a portion of the overlying sandstone had moved 

 upon the underlying shales, the disturbance being apparently a 

 superficial one, of a kind commonly enough observed where 

 massive beds rest on yielding shales on a steep hillside. In 

 other words, the movement appeared to be directly related to 

 the present topography. The deposition of carnotite was here 

 plainly subsequent to the movement and had taken advantage 

 of the small openings and dislocations in the shale afforded by 

 this very recent disturbance. It was reported that some of the 

 best nests of ore had been found in " slide rock," i. e., rock 

 which had slipped to same extent down the slope ; but I was 

 unable to verify this statement further than is indicated in the 

 preceding description. There can be little doubt but that the 

 deposits of carnotite on La Sal Creek are not only very super- 

 ficial in character but very recent in age. 



The Roc Creek Deposit. — The principal claim is the Copper 

 Prince, owned by J. R. Duling, on the north side of Roc 

 Creek, 3 or 4 miles above its mouth, and near the foot of the 

 Miller trail to Paradox. It is reached by this trail from Para- 

 dox Valley, or by trail from Hydraulic on the Dolores River. 

 This deposit is in the La Plata sandstone according to Dr. 

 Spencer's observations, and has been more extensively ex- 

 ploited than any other seen. The sandstone, which at this 

 point is nearly horizontal, is cut by an east and west fault, the 

 fault plane dipping north at about 70°. The amount and 

 character of the throw could not be determined. It is probably 

 less than 50 feet. The carnotite occurs in the hanging wall of 

 the fissure as small irregular branches in a loose mass of crushed 

 sandstone and also as an impregnation of some of the firmer 

 portions of the bed. No roscoelite was seen. Several small 

 tunnels have been run in on the hanging wall side of the fis- 

 sure (which itself carries no vein or ore-body), but they had 



