IRON ORES 



343 



The relations of the Mineville ore bodies have always proved 

 confusing, but it is hoped that the accompanying sections may help 

 to throw some light on them. Referring to the plan of the work- 

 ings as shown on the map, it will be seen that the axial direction of 

 all the ore bodies is southwest and that they lie in two or three 

 parallel ranges. There are irregularities entering in that upset the 

 uniformity of this somewhat, but in general it holds. There are live 

 distinct mines. One is based on the bed, tapped by the Brinsmade 

 and Welch shafts, and is generally called the Welch shaft bed. This 

 dips westward at a varying angle that is nearly vertical at the north 

 end and about 45° at the Welch shaft. In its southern part it runs 

 in under the Old Bed (called in earlier days the Sanford) but a drift 

 has been run through the intervening rock. The widest breast is 

 about 50' from wall to wall but at the northern end it pinches to an 

 unworkable thinness. This bed appears in Section DD. 



Lying over the last but also extending further south is the Old 

 Bed. Old Bed has an axis that runs about S. 30 W. The pitch is 

 quite flat being but 20°. The dip in the eastern workings is much 

 more southerly than the Welch Shaft bed and on the western side 

 it becomes more westerly. The Old Bed is quite complex in form 

 and structure. It starts from the surface with a low dip, as already 

 mentioned, but soon rolls over more and more steeply until it con- 

 nects with a lower lying ore-body, which sets back under its upper 

 portion, and is called the Potts Shaft bed, because opened by a shaft 

 of that name. This same shaft tapped a still lower lying and par- 

 allel bed with which Old Bed also connects down the pitch. They 

 are shown in Sections AA, BB, and CC. The structure can be best 

 summed up, perhaps, as a triple forking of an original bed. The 

 Old Bed, as do also the Miller and " 21," thickens very much from a 

 comparatively thin outcrop to a much greater section lower down. 

 The mining has shown breasts varying from 20 to 125 feet. Mr 

 Putnam of the Tenth Census referred this to the buckling of a sig- 

 moid fold. He makes however no mention of the lower Potts shaft 

 Bed and when this is included, the forking original seems more 

 probable. The ore next the footwall in both Old Bed and 21 is 

 specially charged with apatite. Indeed the workings in 1852 on the 

 former were begun in order to procure phosphates for fertilizers. (W. 

 P. Blake, Trans. Amer. Inst. Min. Eng. Balto. Meeting 1892.) Con- 



