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Show 218 MIOCENE PERIOD• [Ch. XVI. then inhabiting the country were buried. The trachytic breccia d was then superimposed ; this breccia is an aggregate of shapeless and angular fragments of trachyte, cemented by volcanic tuff and pumice, resembling some of the breccias which enter into the composition of the neighbouring extinct volcano of Mont Dor in Auvergne, or those which are found in Etna. Upon this rests another alluvium c, which also contains the bones of Miocene species, and this is covered by another enormous mass of tufaceous breccia. We suppose the breccias to have resulted from the sudden rush of large bodies of water down the sides of an elevated volcano at its moments of eruption, when snow perhaps was melted by lava. Such floods occur in Iceland, sweeping away loose blocks of lava and ejections surrounding the crater, and then strewing the plains with fragments of igneous rocks, enveloped in mud or ' moya.' The abrupt escarpment presented by the abovedescribed beds, b, c, d, e, towards the valley of the Couze, must have been caused by subsequent erosion, whereby a large portion of those masses has been carried away *. In the alluviums c and e, MM. Croizet, J obert, Chabriol, and Bouillet have discovered the remains of about forty species of extinct mammalia, the greater part of which are peculiar as yet to this locality; but some of them characteristic of the Miocene period, being common to the faluns of Touraine, and associated in other localities with marine Miocene strata. Among these species may be enumerated Mastodon minor and M. arvernensis, Hippopotamus major, Rhinoceros leptorhinus and Tapir arvernensis. The Elephas primigenius, a species common to so many tertiary periods, is also stated to accompany the rest. In some cases the remains are not sufficiently characteristic to indicate the exact species, but. the following genera can be determined: the boar, horse, ox, h yrena (two species), felis (three or four species), bear (three * ~""'or an account of the position . and age of the volcanic breccias o~ M~nt Perrier and Boulade, see Lyell and Murchison on the beds of Mont Pemer, Ed. New Phil. Journ., July, 1829, p. 15. Ch. XVI.] ALLUVIUMS-FRESH•WATER STRATA. 219 species), deer, a great variety, canis, otter, beaver, hare, and water-rat *. Velay .-In Velay a somewhat similar group of mammiferous remains were found by Dr. Hibbert.t, in a bed of volcanic scorire and tuff, inclosed between two beds of basaltic lava, at Saint-Privat d' Allier. Some of the bones were found adhering to the slaggy lava. Among the animals were Rhinoceros leptorhinus, H yrena spelrea, and another species allied to the spotted hyrena of the Cape, together with four undetermined species of deer t· At Cussac and Solilhac, one league from Puy en Velay, M. Robert discovered, in an ancient alluvium covered with lava, the remains of Elephas primigenius, Rhinoceros leptorhinus, Tapir arvernensis, horse (two species), deer (seven species), ox (two species), and an antelope. Orleanais.-In the Orleanais, at Avaray, Chevilly, les Aides, and les Barres, fossil land quadrupeds have been found associated with fluviatile shells and reptiles, identical with those found in the marine faluns of Touraine§. These are supposed, with great probability, by M. Desnoyers, to mark the passage of streams which flowed towards the sea in which the faluns were deposited. 'l'hey bear the same relation to the Miocene strata of 'l'ouraine, as part of the ancient gravel and silt of England, containing the bones of elephants and other extinct animals, probably bear to the crag. MIOCENE FRESH-WATER FORMATIONS. Upper Val d'Arno.-There are a great number of isolated tertiary formations, of fresh-water origin, resting on primary and secondary rocks in different parts of Europe, in the same * Recherches sur Jes Oss. Foss. du D~pt. du Pny de Dome, 4to., 18.28.-Essai Geol. et Mineral. sur les Environs d'lssoire, Dept. du Puy. de Dome, folio, 1827. t E<lin. Journ. of Sci., No.4, New Series, p. 276. t Figures of some of these remains are given by M. Bertrand de Doue, Ann. de Ia. Soc. d'Agricult. de Puy, 1828. § MM. Desnoyers and Lockart, Bulletin de la Soc. Geol., tom. ii, p. 336. |