Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/191

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181
Mr. Webster on the Strata lying over the Chalk.


Mytilus very different from those of the calcaire grossier.
Cardium?
Ostrea vesicularis.
———— deltoidea.
Pecten M. Defrance has observed 2 species.
Crania It was adherent and differing in that from known species.
Perna?
Terebratula, many species.
Spirorbis.
Serpula.
Ananchites ovatus The shell is changed into calcareous spar, and the internal part is converted into flint.
Spatangus Cor anguinum Kl.
Porpites.
Caryophyllia
Millepora These are often in the state of brown oxide of iron.
Alcyonia.
Shark's teeth.
§ 2. Lowest Marine Formation over the Chalk.

The clay and sand cliffs of Alum bay afford one of the most interesting natural sections that can well be imagined. They exhibit the actual state of the strata immediately over the chalk before any change took place in the position of the latter. For, although the beds of which they are composed are quite vertical, yet, from