Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/293

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Mr. Bakewell on the Coalfield near Manchester.

siliceous sandstone, similar to that on which the town of Manchester stands, and it is remarkable that within 15 or 16 yards of its contact with that rock, the coal is soft and hardly worth working. This rock stretches through the south of Lancashire into Cheshire and Shropshire, and appears to agree in some respects with the old red sandstone of Werner. I have been told by a considerable proprietor of coal-mines in these counties, and I believe it is an opinion very generally entertained, that this sandstone always cuts off the coal-measures, and that it is useless to search for coal beyond or beneath it.

The Bradford coalfield appears at first sight to offer an exception to this rule; but upon more attentive examination it will be found, that what covers the coal-measures there is not the rock itself, but only a portion of it, washed down from the higher lands, and spread over the surface.

The coal-measures dip to the south at an angle of about 30°, and wherever they have been proved, on the southern side of the field, abut against the sandstone; but on the northern side, at the distance of ten yards from the red rock, a most striking change in the position of the strata is discovered. A bed of coal, four feet in thickness, here rises up to the surface perpendicularly, and terminates the coal measures, the intermediate space between this bed and the red rock being filled with broken stones or rubble without any appearance of stratification. This perpendicular bed has been worked to the depth of forty feet, and is of the same quality and general appearance as a four-feet bed which rises near the middle of the field. The stone that lies over the one agrees with that adjoining to the other, which the proprietor does not doubt is a portion of the inclined bed broken off and thrown into its present position. The distance of the perpendicular bed of coal from the rise of the last bed, that preserves its inclination of 30°, is 325 yards, and between these no fracture or fault has been found to explain the difference in their angles of ele-