LITTLE STRAY HOESE SYNCLINE. 495 



In the description which follows, the mines will be grouped according 

 to the main features of geological structure already outlined in Part I, 

 Chapter V. 



LITTLE STRAY HORSE SYNCLINE. 



As shown in the previous chapter, the eastern portion of the area rep- 

 resented on the Fryer Hill map belongs structurally to the western rim of 

 the Little Stray Horse basin, and the ore horizons of the Little Sliver, For- 

 est City, and Denver City mines, if followed continuously eastward, would 

 finally reach the bottom of the basin. The basin is bowl-shaped, its out- 

 lines being shown on the map by those of the Gray and White Porphyry 

 bodies which fill its depression. 



Southern rim. Through its southern rim runs the zone of cross-cutting 

 White Porphyry, in virtue of which the Blue Limestone along the southern 

 and western rim is supposed to be split into two wedge-shaped sheets. Of 

 these the lower one, which thickens to the south and constitutes the entire 

 thickness of the horizon in the mines of Iron and Carbonate Hills, is buried 

 under the whole overlying White Porphyry under the northern end of 

 Graham Park, and its depth or condition of mineralization is not known. 

 The points nearest to the axis of the basin at which it has been reached are 

 in the Highland Mary (P 52), in Stray Horse gulch on the east, and in the 

 Wolftone (T-5) on the west. 



The upper portion, which wedges out to the south, outcrops under the 

 Wash as indicated on the map, commencing to thin out near the southern 

 edge of the area of the Fryer Hill map, and reaching its thinnest point at the 

 Mahala (T-2). It is proved in the following shafts: The Moyamensing 

 (S 12) strikes iron vein material, which probably forms the outcrop of the 

 Denver City ore body, below the Wash at 115 feet. In the Robert Emmet 

 mine, in Stray Horse gulch, this portion of the Blue Limestone is represented 

 by 50 feet of manganiferous iron, with White Porphyry above and below, 

 the overlying porphyry showing traces of original pyrites which have been 

 dissolved out. The main shaft reached the contact at 110 feet, finding a 

 dip of 30 N. E. and being sunk afterwards 150 feet in underlying por- 

 phyry. The ore thus far extracted has been taken between this shaft and 



