Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/96

68 F³. between the Buffalo mountain spurs and the outcrops on the flanks of Jack’s and Shade mountains.

The Bird’s Eye fossil-ore bed occurs in the center of these lower Clinton shales, once largely mined along the crest of the Shade mountain anticlinal in eastern Snyder county.

These rocks weather readily, and when not covered by loose bowlders of Medina sandstone on the side of the mountain, they furnish a good natural soil, largely argillaceous, but subject to improvement. Its rocks, however, are usually more siliceous than the Middle olive shales.

The Bird’s Eye fossil-ore bed is the most important feature of this division, occurring about 150′ above the base or top of Medina sandstone, and extensively wrought at one time towards the eastern end of Shade mountain in Snyder. Its flat dip and good quality invites development. It is 8″–10″ thick, breaks out in blocks just the thickness of the bed, due to cleavage planes running at acute angles to the strike of the measures. Usually its outcrops occur so high in the mountains, wherever the dip becomes stiff, that it is impracticable to reach it for economical development, so that it is very little known in Mifflin and Juniata counties, and is nowhere mined in Union.

Two other beds have been found locally in Snyder county, although they may be found elsewhere.

1st. The Boyer block-ore, which Mr. Dewees describes as “occurring 250′ to 300′ beneath the Iron sandstone and 100′ to 150′ above the Bird’s Eye fossil-bed.” It is 6′ thick and part of it furnishes good ore where opened in Mahantango Gap northeast of Freemont in Snyder county.

2d. The Shot-block fossil lying below the Bird’s Eye; 6″ to 8″ thick and contains shot-like argillaceous pebbles. It has been wrought in the Lost Creek ridge and Paxtonville quarries in Snyder county.