Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/336

 2nd. Santonian stage: the lower part with Ostrea acutirostris, O. santonensis, Spondylus truncatus, Janira quadricostata, Sphoerulites Coquandi, and Radiolites fissicostata.

The upper part, of fluviatile origin, with Unio, Cyclas, Omphalia Coquandi (Zekeli), and 7 beds of lignite, Cyrena glohosa and Ferussaci, Math., Melanopsis rugosa, Math., and M. gallo-provincialis.

Plan d'Aups, near Sainte Baume, and the environs of Martigues.

This corresponds to the upper portion of the chalk of Gosau.

3rd. Campanian and Dordonian stages, from 400 to 500 metres, equal to from 1333 to 1666 feet, of Lacustrine limestones, with Cyclas gardanensis, Brongniartina, and gallo-provincialis, Math., Ampullaria proboscidea, Math., Paludina angulata, Math., Lymnea longissima, Math., &c., and containing 18 layers of lignites, very different from those which are worked lower down, in the Santonian stage (fig. 3). It is evident that these Lacustrine limestones correspond with the "Upper Chalk " and with my Dordonian stage ; for they are covered by other Lacustrine limestones, which are referred to the level of the limestone of Rilly, and therefore to the base of the Eocene.

Thus in Lower Provence it is evident that a complete change must have been wrought in the nature of the waters of the Cretaceous Sea, which, after the conclusion of the Santonian period, from being salt became brackish, and afterwards, from brackish, fresh — a circumstance which favoured the development of a population of fluviatile shells, entirely unknown elsewhere, and which were contemporary with the gigantic Rudistes of the Charente, and those of Provence, which lived in the immediate vicinity of the lake, at the bottom of which the Carbonaceous deposits were precipitated.

The classification of these Lacustrine sediments had been, until very lately, the cause of great confusion and serious errors. They had been attributed at one time to the Miocene period, at another to the Eocene, without a single reliable argument, or a single fossil in support of this opinion. The new method of determining their chronological order is justified, not only by their position, but also by the very important fact that in the neighbouring Alps, as well as in Algeria, where the upper chalk is exclusively of marine origin, we observe, above the Santonian strata, Ostrea vesicularis and Belemnitella mucronata, species wanting in the corresponding strata of the Bouches du Rhone, which, as we have seen, having been deposited in a lake, can only contain Lacustrine shells. My friend M. Matheron is occupied at the present time in making out a catalogue of this