Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/158

68 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 24, the same disposition of islands, deep and shallow seas, with remote continental spaces and rivers, which now prevails in the coral-areas, must be suggested to have existed in the reef-bearing seas of the past. The simplicity of the physical conditions, and their continuance on some one area during all ages, offer an explanation why the species and genera of the reefs and deep seas are respectively so representative and so evidently formed upon one definite plan.

There are relations, which can only be hinted at in this communication, between the floras and the reptilian and mammalian faunas of present coral-areas and those of the past. But the persistence of coral-seas, with intervals of deep seas and altered physical conditions, during the Liassic, Oolitic, and Cretaceous ages, for instance, may explain the singularly defective mammalian fauna, and the characteristic nature of the reptiles of the strata that contain a flora so representative of the Equatorial coral-seas.

The first land-surface of the Trias in western Europe became, in some localities, a sea, and a coral-sea; and before the end of the period a great upheaval took place, and a second coral-sea—the result of subsidence—was formed. A deep sea in the north and reefs in the east of the area followed, after the prolongation of a stationary condition of some Triassic surfaces, and after an upheaval of others. The reefs of the Lower Lias, so evidently representative of those of St. Cassian, were partly contemporaneous with, and partly successive to, the deep seas of the Rhaetic, which may be regarded as an intercalated series. Europe was a coral-reef area during the Lower Lias; but great bathymetrical alterations then occurred, and consecutive but very closely allied coral faunas appeared on it. The Upper Lias witnessed the culmination of those alterations which were destructive to the reef-faunas. The Oolitic coral-seas which followed had a coral fauna closely allied to, and representative of, the Lower Liassic, although a great break had occurred in the European area between the periods. All the peculiar physical conditions returned, and persisted longer on the Continent than in the space now occupied by England. Coral formation after coral formation appeared and gave way to the overwhelming results of altered sea-depth; but throughout the period the character of the fauna altered but little. The Neocomian period had a reef-bearing sea in the Central-European space, and deep and shallow waters on our area. The physical break which occurred between the Coral rag and the Neocomian, witnessed the destruction of coral-life over large areas; but the two faunas were nevertheless closely allied and representative.

The Green Sands and White Chalk of the north-west of Europe were deposited in increasingly deep seas, whilst the reefs were in full force in Central Europe. The affinities of the reef-builders of this age were not with the corals of the Gault, but with those of the Neocomian; and the deep-sea forms were somewhat representative of those of the very uncoralliferous deep seas of the Gault.

The great break between the Cretaceous and Nummulitic strata in Europe is well appreciated by all geologists; and the opinion of Forbes and Austen, that the Tertiary seas of Europe washed a great