Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/320

 is N. and S. and they dip W. at an angle of about 40°. At the point where these strata crop out, they are very much broken, and irregular in their position; in one place I observed the ends of the strata turned completely up into a vertical position, as is represented in the sketch No. 2. This appearance is however only of partial occurrence, for in returning a few days afterwards to the same place, the quarries had removed that part of the rock, and at the cropping out of the strata then exposed, although they were irregular, they were not in a vertical position. In Chamberlain's quarry, to the north of Pearly Quarry, I also observed the limestone strata becoming more inclined and as it were bent up, towards the point where they crop out at the surface.

§ 54. In the limestone of Pearly Quarry, I obtained a specimen of the vertebra of an encrinite, and which, as I am informed by Mr, Parkinson, is one of a very rare species: the only other specimen of it which he has seen is in the British Museum.

§ 55. To the westward of Pearly Quarry the argillaceous rock is found in conformable stratification with the limestone. It has somewhat of a slaty structure, and includes balls of argillaceous limestone. A road that is cut through this rock exhibits a section of it at right angles to the beating of the strata: it is of very considerable thickness, as the section is about a quarter of a mile in extent, and the same rock continues the whole way. On this there lies a fine quartzose sandstone in thin strata, dipping W. at an angle of 42•, and bearing N. and S. The quartzose sand is united by a calcareo-argillaceous cement with a few spangles of mica disseminated through the mass. In those places where the mica is most abundant, it acquires a slaty structure, and the slates may sometimes be obtained as thin as coarse paper. The colour of the rock, which is derived from a considerable admixture of oxide of iron, is in general yellowish-brown: it