Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/62

 50 these, with the exception of a few of the most superficial, appearing in similar progression in each mine. The clays, or argillaceous stone, of which these beds are composed, are indurated in different degrees, tinged with various shades of red, blue, brown, &c. and usually contain a portion of sulphate of lime. They are known to the miners by the general name of metals; a distinctive appellation being given to each from the shade of colour which it assumes. In the section of strata, annexed to this paper, these appearances are noted with some degree of minuteness; and that they may more accurately be known, I have sent a few specimens, illustrative particularly of the induration of the clay strata, and of their admixture with the sulphate of lime. It will be observed that, though these clays in general possess a considerable degree of in duration, there are some of them sufficiently porous to admit the passage of water through their substance. Where this structure of the clay occurs it goes by the name of the shaggy metal, and the fresh water which makes its way through the pores has the expressive appellation of Roaring Meg. This term will not appear too strong, when it is mentioned that in the mine from which the section of strata was taken, and where the shaggy metal was found at the depth of twenty-six yards, the quantity of water, ascertained to issue from its pores in one minute, was not less than three hundred and sixty gallons; a circumstance greatly enhancing the difficulties of passing a shaft down to the body of rock-salt.

A portion of salt, sufficient strongly to affect the taste, is found to exist in many of these beds of argillaceous stone: and this saltness increases, as might be expected, as we approach the body of the rock-salt. In the strata or layers immediately above the rock, which in all the mines are perfectly uniform in their appearance and structure, it is particularly remarkable. It may be observed, however, that