.

Out of two hundred and ninety species of shells from the _faluns_ Mr
Lyell says he found seventy-two identical with recent species, and that
out of the whole three hundred and two in his possession forty-five only
were found to be common to the suffolk crag. Nevertheless a similarity
of mineral composition, and the general analogy of the fossil shells and
zoophytes, together with the perfect identity of certain species,
strongly justifies the opinion that has long been pronounced, that the
faluns of Touraine, and the Suffolk crag are nearly contemporaneous.

To this brief outline of what may properly be termed the regular
stratifications of Touraine, it only remains to be stated, that they are
frequently concealed by considerable deposits of alluvial and diluvian
beds of flinty gravel, sand, and adventitious clays, in some of which
numerous specimens of the rocks and fossils to be found existing in
_situ_ in the neighbourhood are interspersed.

It is almost impossible to contemplate even the comparatively scanty
catalogue of geological facts just adverted to, without being forcibly
reminded of the remarkable physical transformations which the surface of
the country must have undergone, at distinct, and incalculably distant
epochs; and to speculate on the causes which effected; and the peculiar
circumstances characterizing those revolutionizing periods.

Geology, may indeed, be truly said to be an inductive science, and while
pondering over its natural inferences we find ourselves most
marvellously progressing through a long concatenation of pre-existing
realities, which at every remove may be said to assume more and more the
features of romance!

During the cretaceous period, _Touraine_ had not emerged from the
Ocean, which here was probably studded with Islands constituted of the
primary rocks of Brittany, and those of the older secondary formations
we have noticed as now principally occupying the more southern
provinces. These lands, we may reasonably infer, were adorned by the
luxuriant vegetation of a tropical climate, the fossil remains of which,
are found abundantly dispersed throughout the first formed members of
the tertiary series.

Subsequent to the deposition of the chalk, a retiring of the sea from
this region, and a period of repose, are indicated by the presence of
the _freshwater formation_, but on examining the overlying deposits of
_faluns_, we have the most indubitable evidence, that this quie