Page:A tour through the northern counties of England, and the borders of Scotland - Volume I.djvu/324



The stratification of these works is for the most part more horizontal than that of other great fields of coal, particularly below the bridge to the east of the town, where the general declination to the north-east may be about one foot in seven yards. Brown and white freestone, here called post, and argillaceous schistus of various thickness such hardness, called blue, grey, or black metal, or metal-stone, (according to their hardness, and proportion of gritty and micacious particles) are the accompanying strata, their orders and thickness, as well as of the beds of coal varying in the different works. The coal produced from these mines