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| | Description of the Geology of Mercer County Pennsylvania |
 | | The northern drift covers the entire county, even on the very summit of Keel ridge in Hickory township 1250` A.T. Bowlders of large size are often found in the drift; granite, gneiss, greenstone from New York or Canada, mixed with limestone, sandstone, shale, pieces of coal, and an abundance of bluish-white clay. |
 | | The Mercer iron ore plates of carbonate of iron where they reach a thickness of 1 ½` or 2` have been mined along their outcrops, for the Oregon, Iron City, Clay, Sharpsville, and Mineral Ridge charcoal furnaces. |
 | | Under lie the Shenango shales and flagstone 45`; the Shenango sandstone (Sub-Olean flat pebble conglomerate of McKean county) with nodular iron ore and fish remains, 15`; and the Crawford shales, 90` of which are visible in the north-western corner of the county. |
| www.libraries.psu.edu /emsl/guides/X/mercer.htm (895 words) |
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