Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/67

 Rh as my observations have gone, is perfectly founded in fact. From the mode of working the mines, it is difficult to ascertain the progressive appearance of these figures in a perpendicular plane. It has been stated to me that their form is a pyramidal one, the area enlarging by a determinate ratio of increase as they are traced downwards; but several circumstances induce me to consider this statement as a very doubtful one, and certainly founded upon insufficient evidence.

One very important negative fact remains to be mentioned with respect to the internal structure of the Cheshire rock-salt, viz. that no organic impressions or remains have ever been met with in any of the beds of the mineral, which have been worked in this district. This fact rests on evidence of a satisfactory kind, and I am not aware of more than a single instance adduced in opposition to it, and that of a very dubious nature. The same remark may be applied to the strata of argillaceous stone between the two beds of rock-salt. The veins of rock-salt intersecting these intermediate strata contain principally the fibrous variety of the fossil. It may be remarked too of these strata, that at their junction with the upper and lower beds of rock-salt, the lines of division are nearly as distinct, as that between the upper bed of rock, and the superincumbent layers of argillaceous stone.

Comparative view of the Cheshire and Continental Salt Mines.

The want of sufficient materials with respect to the history of the continental salt-mines prevents me from entering into circumstances of comparison so minutely as I could have wished; considering such comparison to afford the best foundation for inquiries into the origin of the fossil-salt. The best, or rather the only memoir on