Newer Pliocene Strata of the Upper Val D’arno.—When we ascend the Arno for about ten miles above Florence, we arrive at a deep narrow valley called the Upper Val d’Arno, which appears once to have been a lake, at a time when the valley below Florence was an arm of the sea. The horizontal lacustrine strata of this upper basin are twelve miles long and two broad. The depression which they fill has been excavated out of Eocene and Cretaceous rocks, which form everywhere the sides of the valley in highly inclined stratification. The thickness of the more modern and unconformable beds is about 750 feet, of which the upper 200 feet consist of Newer Pliocene strata, while the lower are Older Pliocene. The newer series are made up of sands and a conglomerate called “sansino.” Among the imbedded fossil mammalia are _Mastodon arvernensis, Elephas meridionalis, Rhinoceros etruscus, Hippopotamus major,_ and remains of the genera bear, hyæna, and felis, nearly all of which occur in the Cromer forest-bed (see Chap. 13, p. 191). In the same upper strata are found, according to M. Gaudin, the leaves and cones of _Glyptostrobus europæus_, a plant closely allied to _G. heterophyllus_, now inhabiting the north of China and Japan. This conifer had a wide range in time, having been traced back to the Lower Miocene strata of Switzerland, and being common at Œningen in the Upper Miocene, as we shall see in the sequel (p. 218). Older Pliocene of Italy.—Subapennine Strata.—The Apennines, it is well-known, are composed chiefly of Secondary or Mesozoic rocks, forming a chain which branches off from the Ligurian Alps and passes down the middle of the Italian peninsula. At the foot of these mountains, on the side both of the Adriatic and the Mediterranean, are found a series of tertiary strata, which form, for the most part, a line of low hills occupying the space between the older chain and the sea. Brocchi was the first Italian geologist who described this newer group in detail, giving it the name of the Subapennine. Though chiefly composed of Older Pliocene strata, it belongs, nevertheless, in part, both to older and newer members of the tertiary series. The strata, for example, of the Superga, near Turin, are Miocene; those of Asti and Parma Older Pliocene, as is the blue marl of Sienna; while the shells of the incumbent yellow sand of the same territory approach more nearly to the recent fauna of the Mediterranean, and may be Newer Pliocene.