S4^ A Sketch of the Natural History of 



still lower, without passing through the body of rock-salt. 

 We have thus an ascertained thickness of this bed, of about 

 forty yards, and no direct evidence that it may not extend 

 to a considerably greater depth. 



Though only two distinct beds of the fossil salt have been 

 met with at Northwich, it has been ascertained that the 

 same limitations do not exist throughout the whole of the 

 salt district. At Lawton, near the source of the river 

 VVhetlock, three distinct beds were found, separated by 

 strata of indurated clay; one, at the depth of forty-two 

 yards, four feet in thickness; h second, ten yards lower, 

 and twelve feet thick ; and a third, fifteen yards still further 

 down, which was sunk into twenty-four yards, without 

 passing through its substance. Coal is found and worked 

 within two or three miles of this place*, and the only lime- 

 sinne known in the county of Chester is got from the hills 

 which here form the southern boundary of the plain. In 

 no other parts of the salt district, than at Northwich and 

 Lawton, has the upper bed of rock been worked through. 



The strata passed through in going down to the upper 

 bed of rock are nearly horizontal in position, and very 

 uniform in their structure, con>iisting in every instance of 

 beds of clay and marl; and these, with the exception of a 

 few of the most superficial, appearing in similar prog;ression' 

 m 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, given in 

 my Cheshire Report, these appearances are noted with some 

 degree of minuteness ; and that they may more accurately 

 be known, I have sent a few specimens, illustrative parti- 

 cularly 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 niduration, there are some of them sufficiently 

 porous to admit the passage of water through their sub- 

 sunce. Where this structure of the clay occurs it goes by 

 the name of the shaggy metal, and the fresh water which 

 m*kes its way through the pores has the expressive appella- 

 tion of A'oa?i«ir Me-o-. This term will not appear too strong, 

 when it is mentioned that in the mine from which the sec- 

 tion of strata was taken, and where the shaggy metal was 



• Beyond a great Faull, see Mr. Farey's Dsrb. Rep. p. 147 and 160.— Ed. 



found 



