. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . ing towards d, on the right-hand side; the unconformable strata,c c, are beds of sandstone lying over the coal veins. Supposing coal ANTHRACITE COAL FORISIATION. 153 vein No. 4 to rise to the surface at that point on the estate of A, ad-joining the estate of B, Avhich lies towards d; it is apparent that Awould find only a point of the vein on his land, and that it would beuseless to search in the direction of b for it, since the dip of the veinsis sufficient to
. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . ing towards d, on the right-hand side; the unconformable strata,c c, are beds of sandstone lying over the coal veins. Supposing coal ANTHRACITE COAL FORISIATION. 153 vein No. 4 to rise to the surface at that point on the estate of A, ad-joining the estate of B, Avhich lies towards d; it is apparent that Awould find only a point of the vein on his land, and that it would beuseless to search in the direction of b for it, since the dip of the veinsis sufficient to show that none exists there. But on the estate of B,though no coal came to the surface, still the dip of that which existson the estate of A, would render it probable that coal could be readilyfound—the circumstances of its lying too deep for successful miningbeing considerations which would depend very much on the angle ofdip, and the nature of its position in other respects. Strata are said toform outlayers when they constitute an isolated portion, detached fromthe principal mass of the same bed or region of which they once. FIG. 44. formed a part. (The anthracite coal regions are merely outlayers ofthe great Alleghany bituminous field, which originally comprised oneimmense body.) Thus, in fig. 44, the beds a and b form outlayers ofthe main strata, c and d—the missinff portion having been removedby denundation, while their original identity is fully established bythe accordance of the mineral deposit and position. Strata are alsosaid to form an escarpement when terminating abruptly, as in theabove figure, a and b. The origin of valleys has most generally been referred to the agencyof water; but there are other causes besides this. The surface, as
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
