414 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



ence is therefore justifiable that the whole mass of rock above the tunnel 

 has had a slight movement to the westward since the tunnel was run. 



The underground workings of Carbonate Hill may, for convenience of 

 description, be divided into two groups : 



1. A southern, including the Carbonate, Little Giant, and Yankee 

 Doodle claims, to the east of the main fault, and the jEtna, Glass-Pendery, 

 and other claims, below or to the west of it. 



2. A northern group, including the Crescent, Catalpa, Evening Star, 

 Morning Star, Waterloo, Henriett, and adjoining claims. 



SOUTHERN GROUP OF MINES. 



The description of Carbonate, like that of Iron Hill, will commence 

 with the southern end, reversing the order in which the sections are lettered, 

 because the claims at this end were first opened and because the geolog- 

 ical structure is more clearly and easily shown in their workings. In the 

 Carbonate, Shamrock, Little Giant, and Yankee Doodle claims, east of the 

 fault, the principal developments have been made on what is practically 

 one ore body, running in a northeasterly direction from its outcrop on the 

 Carbonate claim. A noticeable feature of the structure is that this ore 

 body is bounded on the southeast by a prominent fold in the limestone, 

 which bends down very sharply east and, rising again, forms a narrow 

 trough. This is clearly shown in the Carbonate incline, Section I, Atlas 

 Sheet XXX. The region to the southeast of this fold has thus far proved 

 barren of rich ore, although explorations have hardly been carried out to a 

 sufficient depth to warrant the conclusion that another bonanza may not 

 exist in that direction. In the Yankee Doodle and Little Giant claims the 

 ore body is narrow, but widens out as it approaches the surface in the Car- 

 bonate ground, with intermediate ban-en streaks which approximately cor- 

 respond to minor folds more or less parallel with the main folds above 

 mentioned. Practical evidence of the actual replacement of limestone by 

 vein material is extremely common and well defined in the mines of Car- 

 bonate Hill. These, as will be shown in the detailed descriptions of mines 

 which follow, are found in the sudden deepenings of the ore bodies on the 

 limestone side of the contact plane, which by the miners are often con- 



