Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/63

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Mr. H. Holland on the Cheshire Rock-Salt District.
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there are not in these strata any veins of rock-salt, connected with the great mass below: on the contrary, the line of division between the clay and rock-salt is drawn with great distinctness in every instance, and presents none of those inequalities which would arise from a mutual penetration of the strata.

It may, I believe, be considered as a decided fact that no marine exuviæ or organic remains are found in the strata situated over the rock-salt. I have indeed heard it asserted that there are a few instances in opposition to this statement; but upon minute inquiry, I do not find that the accuracy of these alleged exceptions is in any degree to be depended upon.

The general, I believe universal, occurrence of gypsum, in connexion with beds of fossil salt, is a fact worthy of observation. This connexion appears in the salt mines of Hungary, Transylvania, and Poland, as well as in those of Cheshire, and it has led Werner to assign to the rock-salt and flœtz gypsum a conjunct situation in his Geognostic System. The gypsum, contained in the clays over the Cheshire rock-salt, occurs in varying proportions, and under different appearances in the several beds passed through. It is found both in large masses and in small granular concretions. The compact, foliated, and fibrous varieties are all met with; the last of these occurring in very considerable proportion. According to Werner, the first or oldest flœtz gypsum is that which has the most immediate relation to rock-salt. I am not enabled to say whether the gypsum appearing above the Cheshire salt would be considered as belonging to this particular formation. The presence of the fibrous variety of the mineral would rather seem to place it with the second flœtz gypsum where this species is particularly abundant; but no positive distinction can be derived from this circumstance. I may remark that gypsum has been met with in several other parts of the Cheshire