The laws which regulate the deposition of lead ore in veins; illustrated by an examination of geological structure of the mining districts of Alston Moor . ge quantities of leadore were formerly obtained. On the east side of its intersectionwith Old Groves vein the aggregate thickness of the ribs ofpure sulphide of lead lodged between the detached portions ofLittle Limestone amounted to from eighteen to twenty-one feet. In the portion of Browngill vein, comprehended between theoutcropping of the Great Limestone and Firestone strata, therecan be no doubt but that the conditions are favom-able t
The laws which regulate the deposition of lead ore in veins; illustrated by an examination of geological structure of the mining districts of Alston Moor . ge quantities of leadore were formerly obtained. On the east side of its intersectionwith Old Groves vein the aggregate thickness of the ribs ofpure sulphide of lead lodged between the detached portions ofLittle Limestone amounted to from eighteen to twenty-one feet. In the portion of Browngill vein, comprehended between theoutcropping of the Great Limestone and Firestone strata, therecan be no doubt but that the conditions are favom-able to the per-colation and circulation of fluids as low as the Great quantity of lead ore, however, obtaiaed from the vein in thisstratum is comparatively small, and sufficient to repay the costof working only in the neighbourhood of its intersection withOld Groves cross vein, and directly below the very productiveground in the Little Limestone. The throw of the vein placesthe opposite sides of the Great Limestone past each other. Openspaces have been formed, now filled with quartz and other vein CROSS SECTION OF BROMVNGILL VEIN. riATE AND LEAD OBE DEPOSITS. 203 minerals. In tMs respect, it differs from the Nenthead powerfulcross veins, which, as pointed out, seldom contain much veinmineral when they dislocate the strata very much. Either thelead ore has been abstracted from the vein by some natural cause,or its non-deposition is the result of the interference of somecauses at present unknown, but which seem connected with thegreat amount of dislocation of the vein; for Browngill sunvein, a comparatively weak one, not dislocating the strata morethan twelve feet, under precisely similar conditions for pro-moting the percolation and circulation of fluids, and running ina parallel direction, has contained much lead ore, not only in theGreat Limestone, but even as low as the Four-fathoms may, however, be remarked that the lead ore in Browngillvein in the
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1861
