BETWEEN WESTON AND MIKE FAULTS. 233 



Head of California gulch. At the head of California gulch, on the north, 

 the Ohio Bonanza tunnel (not on map) runs in at the surface of a fragment 

 of Blue Limestone which has been left above the White Porphyry; still 

 higher up, the Snowbird shows a sandstone completely impregnated with 

 pyrite and surrounded by Pyritiferous Porphyry, which is supposed to be 

 a detached fragment of Weber Shales. On the south side the Tinker 

 (E 43) shaft has penetrated the White Porphyry to the underlying lime- 

 stone. The Belle Vernon shaft was sunk through 80 feet of Wash and 150 

 feet of White Porphyry without reaching it. 



The occurrence of Wash here in California gulch is significant, as 

 showing that the Iowa gulch glacier must at one time have filled the 

 valley to the height of the saddle east of Printer Boy Hill and a part of its 

 moraine material must have been pushed over into the head of California 

 gulch, or else that a portion of the glacier actually extended over the ridge. 

 In the lower part of the gulch there is no evidence of glacial action. 



Pyritiferous Porphyry. On the south side of Green Mountain, overlooking 

 Iowa gulch, is the Alta tunnel, which runs 30 feet through Wash, 63 feet 

 through White Porphyry, and 192 feet into the overlying body of Pyri- 

 tiferous Porphyry, here dipping northeastward, while the North Star shaft 

 (E 23), just above it, is sunk in Pyritiferous Porphyry. The rock here, 

 though characteristic, does not contain much pyrite, except at the end of 

 the Alta tunnel, where it is associated witli stains of galena. Little SchuyL 

 kill shaft, in the south head of California gulch, has been sunk through 

 Pyritiferous Porphyry into the underlying White Porphyry, while the 

 Ella and adjoining (F-38) tunnels are run in Pyritiferous Porphyry. All 

 these shafts are just below the Weston fault, and the Pyritiferous Porphyry 

 belongs to the main sheet which covers the greater part of the slopes of 

 Breece Hill, and which corresponds with the lowest sheet east of the fault, 

 viz, that found just above Idaho Park. 



In California gulch, as already stated, there is a still lower body of 

 Pyritiferous Porphyry, whose rock, though not absolutely identical with 

 the other, resembles it closely enough to form a part of the same body, 

 and which comes at different points in contact now with the Blue Limestone 

 and now with the White Limestone. It is therefore supposed to be cutting 



