1869.] DUNCAN—CORAL FAUNAS OF WESTERN EUROPE. 53
There has been much progress made in connecting the phenomena
of existing reefs with those of the past, with the idea of establishing
propositions upon which geologists could reason. Many years since,
Lieut. Nelson* proved that sediments which were supposed to be
characteristic of Oolitic and Cretaceous rocks were imitated around
the Bermudas; and of late years much has been written upon coral
limestones and marls, and the metamorphosis of coral rocks into
dolomites has been hinted at†.
Speculations have also been published respecting the influence of the subsidence of reefs, their becoming covered up with deep-sea deposit, and the creeping of deep seas over littoral tracts and land upon the notions of contemporaneity‡.
In 1863§ the similarity in general arrangement of the Miocene reefs of the West Indies to those now encircling many of the islands was announced; and it was stated that the species of the old reefs could be divided into those which lived amongst the boiling surf, in the quiet lagoon, along a barrier reef, and in deep water close by. The raised reefs of San Domingo were shown to link the specialities of existing reefs to those of the past; and an examination of still older coral formations on the same area indicated that even in the Lower Cretaceous rocks there were proofs that the same external conditions and the same grouping of coral forms were as characteristic of the ancient as of the Caribbean reefs.
Again, the study of the Sicilian and Crag deposits proved that the former seas, out of the range of reefs, had coral species representative of those now living in deep and abyssal water, and occasionally just below low spring-tide mark.
Moreover many English geologists|| had shown that coral reefs formed parts of Palaeozoic and Oolitic landscapes; and Stoppani¶ proved that the Azzarolan banks were formed by a branching Madreporarian.
With these facts and theories at hand there is a demand for their utilization in some common inquiry; and this communication is an attempt to explain some of the former physical conditions of Western Europe by comparing the fossil coral faunas with the existing**.
It commences with a notice and a description of the typical species of the coral fauna of the deep and abyssal seas which bound continents remote from reef areas; and then follow remarks upon
- Trans. Geol. Soc. 2nd ser. vol. v.
† S. P. Woodward held this opinion. (Geol. Mag. vol. i. "Review of the Dolomite Mountains.")
‡ Duncan, Report on Brit. Foss. Corals, Brit. Assoc. 1868, 1869.
§ Quart. Journ. Geol. Soc. vol. xix. p. 406.
|| Ramsay and Murchison; Wright, Cotteswold Club, 1868.
¶ Pal. Lombard.
- Some theoretical considerations bearing upon this communication will be
noticed in:—Description Foss. Corals of the West India Islands, 1863. Report on British Fossil Corals, read at Norwich, 18G8, and Exeter, 1869. Palaeontograph. Soc. Supp. Brit. Foss. Corals, 1865. Tertiary (written 1864). Since this essay was read the specimens of corals dredged up in the 'Porcupine' expedition have been examined by me, and Count Pourtales has sent me most of the types of the deep-sea coral fauna off Florida and the Havannah. I still find that the deep-sea coral faunas differ essentially from those of coral-reef areas.
