Notes on the Metalliferous Saddles, or Orebearing Beds in the Contorted Strata of the Lower Carboniferous Rocks of Certain Parts of Derbyshire and North Staffordshire

Abstract

The inferior division of the Carboniferous series in Derbyshire and North Staffordshire, composed of calcareous rocks and shales, and forming the Mountain Limestone group of those counties, presents, particularly about the neighbourhood of Alstonfield, some very interesting and remarkable associations of metallic minerals with certain mechanical disturbances of the strata; moreover, these associations are not to be indiscriminately classed with the general phenomena of the mineral veins of the districts in question, but must be considered as special facts requiring a separate consideration and explanation. Their existence is no new discovery, since they have been recognized from the earliest times that mines have been worked in the places where they occur, and where also they are at most times regarded as valuable features, inasmuch as the richest deposits of ore have been found in connection with them; indeed, so decidedly has this been the case, that, in working the mines, much of the future success has been calculated by the amount of probability of any particular vein intersecting the disturbed beds; such unions having, in nearly all cases, been attended with most important results, both as respects the quantity, as well as the kind of ore met with. Nevertheless, I am not aware of their having ever received any particular attention from geologists, nor of their having been anywhere described, circumstances which may probably arise from the fact of these beds only being visible below the surface, and usually in deep mines; or they may have remained unnoticed, from the really small amount of scientific observation which in this country has been brought to bear on the facts connected with metalliferous deposits, compared with what has been done, and is still doing, in other branches of physical geology. The present article is drawn from memoranda made during several careful surveys of mines which are notable, in North Staffordshire, for exhibiting the phenomena of the saddles in great force.