Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/322

294 F³. of the ore the Marcellus limestone exists, occasionally forming the foot-wall of the ore-bed, but usually sepparatedseparated [sic] from it by from 6′ to 10′ of buff colored clay. The north outcrop contains ore from 2½′ to 8′ thick overlaid by from 10′ to 15′ of black slate to the “overlap vein,” which was apparently a tightly folded roll in the ore-bed (having no connection with the main bed of either side of the valley) and which is said to have furnished a very large quantity of excellent brown hematite ore from 25′ to 30′ thick.

About 145′ above the creek the main ore-bed was opened by a gangway driven west for some distance under the highest part of the hill. Carbonate ore was obtained in this entry; but the on driven up the rise of the bed towards the outcrop nearly all developed the bed altered to brown hematite.

The main drift in the recent operations is located about 300′ above the creek level and bears northwest for about 400′, striking there the south bed dipping 75° towards the northwest. One gangway was driven along this bed 400′ long, and 210′ beneath the summit of the hill. Breasts had been carried up for about 50′ on the bed, about 15′ to 18′ wide each, leaving pillars between 10′ to 12′ wide. The ore-bed here is said to be from 10′ to 12′ thick, which is an unusual development of the Marcellus measures.

From the entrance of this gangway the main drift was carried 300′ further across the measures before striking the north vein; and it is to be remarked that in this drift no evidence was seen of the “overlap vein” which evidently basined or feathered out before reaching the depth or level of this gangway. After striking the north bed, which was of varying size, the main gangway was pushed on some 400 or 500 feet further. The same system of mining was adopted here; but the ore itself was almost entirely altered to brown hematite, until near the head of the gangway the carbonate was struck and was stoped upon at that point for a height of about 50′ above the entry. The dip here was about 45° to the southeast and it would appear that the existence of the bed both on this and the north dip, whether as carbonate or brown hematite, depends somewhat upon