| Geological Survey of Pennsylvania - Geology - 1836 - 686 pages
...XVI. LIMESTONE. % Resting on the above, and immediately underlying the Pittsburg coal seam, is a bed of limestone of characteristic appearance and remarkable...with which it accompanies the coal. It consists of bjue and black limestone in layers from six to ten in number, separated by shale. One of these layers... | |
| Geological Survey of Pennsylvania, Pennsylvania. State Geologist (1836-1841) - Geology - 1839 - 136 pages
...XVI. LIMESTONE. Resting on the above, and immediately underlying the Pittsburg coal seam, is a bed of limestone of characteristic appearance and remarkable...limestone in a close and continuous stratum. These layers are from one to two and a half feet in thickness and vary in their color, which is generally... | |
| Daniel Dale Condit, Geological Survey of Ohio - Geology - 1912 - 454 pages
...originally denned by HD Rogers, as follows: "Immediately underlying the Pittsburg coal scam is a bed of limestone of characteristic appearance, and remarkable...consists of blue and black limestone, in layers from 6 to 10 in number, separated by shale * * * The average thickness of the whole stratum is 25 feet."'... | |
| Ohio. Division of Geological Survey - Geology - 1912 - 460 pages
...originally denned by HD Rogers, as follows: "Immediately underlying the Pittsburg coal seam is a bed of limestone of characteristic appearance, and remarkable...consists of blue and black limestone, in layers from 6 to 10 in number, separated by shale * * * The average thickness of the whole stratum is 25 feet."»... | |
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