Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/192

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Mr. Webster on the Strata lying over the Chalk.

the nature and variety of their composition, from the great regularity and numerous alternations of the layers, and the other circumstances which have been already mentioned, no one who has viewed them with attention can doubt, that they have suffered no change except that of having been moved with the chalk from the horizontal to the vertical position.

The whole of these strata have evidently been formed at the bottom of an ocean, from the nature of the fossils contained in them, which, although entirely different from those of the chalk, are yet all of marine origin.

The chalk, A, which forms the side of Alum bay, (Plate 11. Fig. 2.) is somewhat harder than usual, and the flints are shivered, so as to come to pieces on being taken out.[1]

Plate 11, Fig. 2.

Next to the chalk, on the north, stands the bed of chalk marl a, which has been already mentioned.

To this succeeds a thick bed of clay, b, of a dark red colour, often streaked or mottled with yellow and white; towards the south side is a thin layer of greenish-grey sand. This is divided by a bed of yellowish white sand, c, from a very thick bed of dark blue clay, d, which contains much green earth; and also nodules of a dark coloured limestone, in which I found a few fossil shells: this bed, however, I am inclined to think, is not continuous for a great extent, as in a part of the cliff farther inland and in the line of its direction, it had almost disappeared.

Next follows a vast succession of beds of sand of different colours, which, though not distinctly separable from each other, yet may be considered as divided into the following:

  1. See the paper on this subject, by Sir Henry Englefield, in the Transactions of the Linnean Society.