AEBA XOETH OF BREECE FAULT. 241 



at depths below rock surfiice of 170 feet, 45 feet, and 50 feet, respect- 

 ively, the latter having also 70 feet of Wash. The Hidden Treasure tun- 

 nel (P-7) is run in on the contact line. The William and Mary tunnel 

 (P-12) runs on the contact of the Parting Quartzite and White Limestone, 

 and the Sappho shaft develops the contact of White Limestone, dipping 10^ 

 east, with underlying White Porphyry. This White Porphyry is the lower 

 sheet which occurs normally between the Blue and White Limestones, and 

 the White Limestone developed in the two shafts is evidently a portion 

 split off from the main formation by this porphyry sheet atid left above it. 

 The White Rabbit (P-17) and Little Stella are sunk in the lower sheet 

 of White Porphyry, the latter having reached the main body of White 

 Limestone below it. The Bismark (P-20) and Holden (P-24) are sunk 

 in the lower portion of the White Limestone, near the crest of the fold, the. 

 latter having reached the Lower Quartzite beneath it. 



On the west of the fold the J. B. Grant and the Dania (P-30) are 

 sunk through the lower sheet of White Porphyry into the underlying Lime- 

 stone, while the First Chance (P-37), Bobtail (P-40), and the Cordelia 

 Edmonston find Blue Limestone, or the vein material which replaces it, 

 immediately below the Wash. These outcrops form part of the eastern 

 member of the Little Stray Horse syncline. 



South slope of Yankee Hill. — On the south side of Yankee Hill, towards Stray 

 Horse gulch, the simple anticlinal structure shown above is considerably 

 complicated. The first disturbing element is the Ii"on fault, which may be 

 regarded as the result of an anticlinal fold, since the beds dip away from it 

 on either side. Hence, an eastern dip is found here in a position on the 

 slope corresponding to the western dip shown in the last-mentioned shafts, 

 and, by the movement of the fault. Lower Quartzite and Archean outcrops 

 are ex]Dosed directly east of it. Besides this, there extends from the crest 

 of the hill southward across Adelaide Park a large mass of porphyry resem- 

 bling Gray Porphyry, which splits the Blue Limestone, and which, from 

 the meager data obtainable, seems to be cutting up across the formation 

 from below. For convenience of description this mass of porphyry will 

 be called the Adelaide body. Near the crest of Yankee Hill a considerable 

 body of iron-vein material has been developed, which j^asses into Blue 



MON XII 16 



