B] TWEEN mON-DOME AND CARBONATE FAULTS. 251 



synclinal structure of Little Stray Horse Park, which is on the direct noiih- 

 ern continuation of this block, continues in modified form to the southward. 

 It is very probable, therefore, that the contact rises to the eastward before 

 reaching the Iron fault along- its entire extent, though it is impossible to say 

 at what angle. In the Agassiz, Greenback (0-53), and adjoining shafts a 

 sheet of vein material of relatively small thickness is found dipping to the 

 northeast, with White Porphyry on either side. This represents a portion 

 of the Blue Limestone which has been split off from the main body by the 

 cutting down of the "White Porphyry ; that is, the lower sheet of White Por- 

 phyry here crosses the Blue Limestone formation at a low angle, leaving 

 wedge-shaped portions of the latter above and below it overlapping each 

 other. The folding of the Little Stray LLorse syncline and subsequent 

 erosion have produced a curved line of outcrop, ajjproximately as given 

 on the majx The thin streak of blue on the south side of Stray Horse 

 gulch represents a thin sheet split off from the main body of Blue Lime- 

 stone, which to the northward thickens so as to include the whole of this 

 body on Fryer and Yankee Hills ; while here the bulk of the Blue Lime- 

 stone is separated from this thin sheet by a great thickness of White Por- 

 phyry, probably not less than COO to 800 feet. 



The Greenback shaft, after passing through Wash and Lake beds and 

 10 feet of White Porphyry, found vein material and limestone in a thick- 

 ness of f)5 feet. The Mahala (T-2) passed through 345 feet of overly- 

 ing White Porphyry, 10 feet of vein material, and 10.") feet of underlying 

 White Porphyry. The Agassiz j^assed through 40 feet of overlying White 

 Porphyry, 5 feet of shales, and 30 feet of vein material. The Gone- 

 Abroad (T-4) also found vein material, after passing through White Por- 

 phyry, at a depth of about seventy-five feet. The Robert Emmet shaft 

 (S-3), after passing through 210 feet of Wash and White Porphyry, cut 

 50 feet of vein material and passed again into White Porphyry, showing a 

 considerable thickening in the body of vein material to the northward. An 

 actual outcrop of this body of iron is found on the south side of Stray 

 Horse gulch, near the Robert Emmet tunnel (S-13). The Wolfe Tone shaft 

 (T-5), which is about five hundred feet west of the Agassiz, has beei? 



