350 A Sketch of the Natural History of 



sea, may perhaps be admitted as another argument in be- 

 half of the opinion. 



The principal objection to the theory undoubtedly is, the 

 non-existence of marine exuviae either in the rock salt or 

 in the adjacent strata of clay; a fact very difficult to con- 

 nect with the idea of a deposition from the waters of the 

 sea. Other objections, though perhaps of less moment, 

 arise from the appearance of the earthy salts in smaller 

 proportion in the rock-salt than in sea water; from the 

 apparently partial deposition of the beds, and from the 

 didiculty of explaining tlie formation of the figured ap- 

 pearances which occur in the substance of the rock. These 

 circumsiancesj however, will by no means authorize us to 

 reject the general idea which has been given of the origin 

 ot this mineral, strengthened as it is by the situation and 

 appearances observed in the foreign salt mines, where the 

 proofs of marine deposition are still stronger than those 

 presented in the Cheshire district. 



I confess I see no sufficient reason for supposing the 

 action of subterraneous or internal heat in the fonnation of 

 the beds of fossil salt. It appears probable that a deposition 

 of muriate of soda from the confined waters of the sea 

 might have taken place without the intervention of this 

 agency, and there are no appearances either in the beds of 

 salt, or in the clays accompanying them, which render it 

 necessary to have recourse to the supposition in question. 

 It must be acknowledged, however, that it is difficult to 

 give a satisfactory account of the consolidation of the beds 

 of salt; nor do I know any opinion on this subject, which 

 can be considered altogether free from objection. A more 

 enlarged discussion of these theoretical points may be 

 found in the Appendix to the Report of Cheshire, before 

 alluded to. 



In dwelling thus minutely upon the natural history of 

 the Cheshire rock-salt district, I am not aware that I have 

 gone further than was requisite to a complete view of the 

 subject. The prosecution of such inquiries is much assisted 

 by the comparison of facts observed in different situations ; 

 and as the neighbourhood of Droitwich, in Worcestershire, 

 is, with the exception of the Cheshire salt district, the most 

 considerable source of brine springs in this kingdom, some 

 information with respect to the situation and natural history 

 of these springs, as connected with a subjacent body of 

 rock-salt, may bs considered a desirable and important ob- 

 ject. Such information 1 have not the means of giving ; 

 but it is more than probable that the Geological Society 

 will be enabled to procure it, by the assistance of some of 

 its corresponding members. Section 



