214 
ELEMENTS OF GEOLOGY. 
The principal grounds, howeyer, for referring the English 
Crag to the older Pliocene and the French faluns to the Up¬ 
per Miocene epochs, consist in the predominance of fossil 
shells in the British strata identifiable with species not only 
still living, but which are now inhabitants of neighboring 
seas, while the accompanying extinct species are of genera 
such as characterize Europe. In the faluns, on the contrary, 
the recent species are in a decided minority; and most of 
them are now inhabitants of the Medi¬ 
terranean, the coast of Africa, and the 
Indian Ocean ; in a word, less northern in 
character, and pointing to the prevalence 
of a warmer climate. They indicate a 
state of things receding farther from the 
present condition of Cental Europe in 
physical geography and climate, and 
doubtless, therefore, receding farther 
from our era in time. 
Among the conspicuous fossils common 
to the faluns of the Loire and the Suffolk 
Crag is a variety of the Valuta Lamberti^ 
a shell already alluded to (p. 196, Fig. 
123). The specimens of this shell which 
I have myself collected in Touraine, or 
have seen in museums, are thicker and 
Variety" heavier than British individuals of the 
species, and shorter in proportion 
to their width, and have the folds on the 
columella less oblique, as represented in the annexed figure. 
Upper Miocene Strata of Bordeaux and South of Prance— 
A great extent of country between the Pyrenees and the 
Gironde is overspread by tertiary deposits of various ages, 
and chiefly of Miocene date. Some of these, near Bordeaux, 
coincide in age with the faluns of Touraine, already men¬ 
tioned, but many of the species of shells are peculiar to the 
south. The succession of beds in the basin of the Gironde 
implies several oscillations of level by which the same wide 
area was alternately converted into sea and land and into 
brackish-water lagoons, and finally into fresh-water ponds 
and lakes. 
Among the fresh-water strata of this age near the base of 
the Pyrenees are marls, limestones and sands, in which the 
eminent comparative anatomist, M. Lartet, has obtained a 
great number of fossil mammalia common to the faluns of 
the Loire and the Upper Miocene beds of Switzerland, such 
as Dmotherium giganteum and Mastodon angustidens ; also 
Fig. 13T. 
