 | 1907 - 1026 стор.
...along the bedding plane or by a shale bed, thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | Geological Survey (U.S.) - 1907 - 532 стор.
...along the bedding plane or by a shale bed, thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | 1907 - 532 стор.
...along the bedding plane or by a shale bed, thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable part in the northeast e.nd of the district, but the upper bench is of most importance throughout the rest of the... | |
 | Ernest Francis Burchard - 1910 - 248 стор.
...along the bedding plane or by a shale bed, thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | Ralph Arnold - 1910 - 958 стор.
...along the bedding plane or by a shale bed, thin at first, but thickening gradual!}' to the southwest. The middle of the Big seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | 1916 - 1150 стор.
...along the bedding plane, or by a shale bed, thin at h'rst. but thickening gradually to the southwest. The middle of the Big seam Is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | Industrial Development Manufacturers Record - 1924 - 452 стор.
...either by a parting along the bedding plane or by a shale bed which thickens gradually to the southwest. The middle of the Big Seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
 | 1909 - 822 стор.
...along the bedding plane or by a shale bed — thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable part in the northeast end of the district, but the upper bench is of most importance throughout the rest of the... | |
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About the middle of the district the seam becomes separated into two benches, either by a well-defined parting along the bedding plane or by a shale bed, thin at first, but thickening gradually to the southwest. The middle of the Big seam is the workable... 