Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/359

 formation prevail; I shall now point out some of the most extensive quarries where they are worked.

§ 13. At Allercot, about four miles south of Minehead on the road to Dulverton, the principal bed of limestone is 30 feet thick. It is of a bluish grey colour, variegated with red, of a crystalline structure, and full of small laminæ of calcareous spar disseminated in detached spots through the mass, which are most probably the remains of organized bodies. Besides this great bed, there are several others of less thickness contained in the slate, and the thinner beds are of an iron-grey colour. The slate is one of those line grained varieties which approach very nearly in appearance to the clay slate of a primary country; it is very much contorted, and the curvatures are often so small as to be seen in a cabinet specimen. Is is very much traversed by veins of quartz. I was informed by the workmen at Allercot that there are quarries of a similar kind of limestone at Westcot, Treborough and Leigh. At Treborough a very excellent roofing slate is obtained.

§ 14. At Doddington, Friern farm, and Ely green, on the eastern side of the Quantock hills, the quarries are very extensive. In those of Friern farm I found some of the beds to be a very close grained crystalline limestone without the slightest appearance of any organic remains; but upon a close examination of the stone when broken in different directions, and particularly at those places where, it is bruised by the stroke of the hammer, I found many parts of the bed to be almost entirely composed of a madrepore. Towards the exterior, madrepores are very distinctly seen, and in some of the beds the stone is full of circular bodies composed of large crystalline plates of calcareous spar, which I have little doubt are entrochi, but I did not discover a shell any of description.