MIOCENE FORMATIONS—MARINE.

Having treated in the preceding chapters of the older and newer Pliocene formations, we shall next consider those members of the tertiary series which we have termed Miocene. The distinguishing characters of this group, as derived from its imbedded fossil testacea, have been explained in the fifth chapter (p. 54). In regard to the relative position of the strata, they underlie the older Pliocene, and overlie the Eocene formations, when any of these happen to be present.

The area covered by the marine, fresh-water, and volcanic rocks of the Miocene period., in different parts of Europe, can already be proved to be very considerable, for they occur in Touraine, in the basin of the Loire, and still more extensively in the south of France, between the Pyrenees and the Gironde. They have also been observed in Piedmont, near Turin, and in the neighbouring valley of the Bormida, where the Apennines branch off from the Alps. They are largely developed in the neighbourhood of Vienna and in Styria; they abound in parts of Hungary; and they overspread extensive tracts in Volhynia and Podolia.

Shells characteristic of the Miocene strata are found in all these countries, figures of some of which are given in Plate 2 in this volume. They characterize the period, because they are either wanting or extremely rare in the Eocene or Pliocene formations.

We shall now proceed to notice briefly some of the countries before enumerated as containing monuments of the era under consideration.