Page:A Treatise on Geology, volume 2.djvu/239

 CHAP. IX. mass of the range is trachytic conglomerate, from beneath which, at intervals, trachyte of different kinds emerges, and encloses craters at the southern end of the range. Some of these craters are, like those in the Eifel, converted to lakes. Exhalations of hot sulphureous vapours are poured out from rents in the hill of Budoshegy; sulphureous, chalybeate, and carbonated waters rise at the foot of this mountain in many places.

In Styria, the Gleichenberg, a trachytic mountain enveloped in strata of ashes, perhaps accumulated in water, indicates considerable volcanic energy during the tertiary æra. At several other points in Styria volcanic masses appear.

The Euganean hills south of Padua constitute a very remarkable mass of volcanic deposits, consisting principally of trachytic rocks, associated with semi-vitreous masses, and at Monte Venda with basalt. The subjacent calcareous strata of "scaglia" contain many fossils of the European chalk. North of Vicenza, the variety of volcanic products is considerable, and it is thought their differences are partly related to the place which they occupy in the series of strata there occurring, between the primary slates and the scaglia. On the volcanic rocks rest calcareous and tufaceous deposits; and at particular places, especially Monte Bolca, fishes occur abundantly in slaty bituminous marls, which alternate with volcanic sediments, often containing shells, like the trass and puzzolana.

Near Viterbo (Monte Cimini), trachytic rocks abounding in leucite, associated with basalt, and beds of pumiceous tufa, covering bones of quadrupeds, are connected with tertiary marls and shells. Near Radicofani the same trachyte occurs in the Monte Amiata.

A few miles south-west of Volterra, near Monte Rotondo, and near Monte Cerboli, sulphuretted hydrogen rises abundantly from little crater-shaped openings (lagunes), and boracic acid is sublimed therewith, as well as in the crater of the island of Volcano.