858 STRATIGRAPHICAL GHOLOGY.  [Boox VI. : 
the Old World and the New, has described about 50 species of plants, 
which, he says, place this Devonshire group of strata on the same geolo- 
gical horizon with some part of the Molasse or Oligocene (lower Miocene) 
groups of Switzerland. Among the species are a number of ferns 
(Lastreea stiriaca, Pecopteris (Osmunda) lignitum, &c.); some conifers, 
particularly Sequoia Couttsix, the matted debris of which forms one of 
the lignite beds ; cinnamon trees, evergreen oaks, custard-apples, eucalyp- 
tus, spindle-trees, a few grasses, water-lilies, and a palm (Palmacites). 
Leaves of oaks, figs, laurels, willows, and seeds of grapes have also been 
detected—the whole vegetation implying a subtropical climate. More 
recently, however, Mr. Starkie Gardner has expressed the opinion that 
this flora is on the same horizon as that of Bournemouth, that is, in 
the middle Eocene group.” If this view be established the volcanic 
rocks of the north-west, with their leaf-beds, may be also relegated to 
the Eocene period. In the meantime, however, they are placed in the 
Oligocene series as probable equivalents of the brown-coal and molasse 
of the Continent. ‘These leaf-beds occur in thin local patches inter- 
calated among the great basalt-sheets already referred to (p.258). The 
plateaux of Antrim, Mull, Skye, and adjacent islands are composed of 
successive outpourings of basalt, which are prolonged through the Faroe 
Islands into Iceland, and even far up into Arctic Greenland. In Ireland - 
the basalts attain a maximum thickness of 900 feet; in Mull about 
3000 feet. They are associated with tuffs, pitchstones, trachytes, and 
granitoid rocks, but more especially with a prodigious number of basalt 
dykes, which, as already stated (pp. 258, 555), probably occupy the 
fissures up which the basalt of the plateaux rose. It is evident that 
long-continued and vigorous volcanic action took place in these north- 
western regions. 
Paris Basin.—In this area, where a perfect upward passage is 
traceable from the Hocene into the Oligocene beds, the latter are com- 
posed of the following subdivisions :* 
Meulieres de Montmorency, very hard siliceous, cellular, fossiliferous, 
fresh-water limestones employed for millstones (Limnwxa, Bythinia, 
Planorbis, Valvata, Chara). This deposit is replaced towards the 
south by the fresh-water Calcaire de Beauce. (80 feet.) 
Gres de Fontainebleau. Sands, and hard siliceous sandstones. At the 
top of this subdivision there occurs at Ormoy near Etampes and 
elsewhere a band of calcareous marl full of marine fossils (Cardita 
Bani, Cytherea incrassata, Lucina Heébertt). 
Sables de Fontenay, Jeurre et Marigny, a thick accumulation of yellow 
ferruginous unfossiliferous sands, covering a large area around Paris, 
and serving as a foundation for most of the new military forts of 
that locality. 
Marls with oysters and marine molasse, containing at the base a bed 
of Ostrea longirostris, higher up a thick bed with O. cyathula, and 
at the top beds with Oorbula subpiswm. 
Calcaire de Brie. 
few marls consisting of an upper mass of non-fossiliferous clay, and a 
Middle. 
Upper. 
—————_-“- eres i ee 

Sable d’Etampes. 
lower group of fossiliferous laminated marls (Cerithiwm plicatum, 
“* ‘ 
Psammobia plana, Cyrena convexa), 

1 Phil. Trans. 1862. 
2 “ British Eocene Flora,” Palwont. Soc. 1879, p. 18. 
* Dollfuss, Bull. Soe. Géol. France, 8e sér. vi. (1878), p. 298. 
