Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/153

1869.] DUNCAN CORAL FAUNAS OF WESTERN EUROPE. 63 Cidaris florigemma and the coral-reef were distinguishable. The lower part of the Kimmeridge group contains the relics of a reef in the Rochelle district; but there are only deep-sea Mollusca and Ammonites to indicate the marine conditions in England, Central Europe, and the rest of France.

Coral-life had departed from our area, and did not return during the deposition of the Kimmeridge Clays; but a small reef-area, where one species of Coral alone is found, existed during the Portland Oolite. But elsewhere in Western Europe* there was always a reef in some locality or other during the very varying conditions of sea-depth of the Kimmeridge age. In the middle part of the Kimmeridge, on the horizon of Pteroceras Oceani and Ammonites mutabilis, the coral-area was around Natheim and in Franconia; and in the upper part, the coral-sea was still absent in the west, but there were reefs in Franconia which were of the same general age as the Solenhofen slates. There was a deep sea on our area and evidences of land close by; and the same evidences presented themselves in Western Switzerland. The variations in the depth of the sea-bottom must have been very considerable to have destroyed reefs in one area and to have enabled them to exist in another and to be again succeeded by deep-sea and even terrestrial deposits. The species of these wandering and successive reefs are identical or closely allied.

The last glimmer of the Oolitic coral-life in Western Europe was in the Portland Oolite; and the feeble reef of our area was part of a system which reached to Western Switzerland. But the progress of a great and general elevation of the Oolitic sea-bottoms had been gradually overcoming the temporary subsidences of portions of the area, and finally the land-surface of the Wealden arose over large spaces.

Neocomian Strata.

Until lately, the strata of this part of the Cretaceous Formation in England were supposed to have been almost uncoralliferous, only one species having been described. Mr. C. J. Meyer, however, has studied the Bargate stone, and has furnished me with some specimens which give a definite character to the Neocomian sea of the south of England.† The species are such as would, in the existing seas, denote a moderately deep sea and littoral tracts remote from, but still under the influence of, a reef-area. They are not true deep-sea species. Now the reefs of the Neocomian period closest to our area were about St. Dizier (Haute Marne) and in the Department of the Yonne. There were others in the Hautes Alpes; and the German reefs were around Schoppenstedt, Elligser, and Berklinger. The reefs of the Yonne were as abundant in species as those of the Oolites. Although the same genera were present, the species were not identical; they were representative and grouped in the same manner. There must have been some great physical break between the formation of the Neocomian reefs and the destruction of those that pre-


 * Waagen, Quart. Journ. Geol. Soc. vol. xxi. part 2, p. 14.

† Pal. Soc.: P. M. Duncan's 'Brit. Foss. Corals,' 1869.