52 Mr Lyell on the Age of the 



phiny ; and if there had been, they would not throw light on the 

 date of eruptions in Auvergno. 



But to return to the lava-stream of the Puy de Tartaret before 

 alluded to — what geological antiquity can we assign to it \ In one 

 of the gorges, the entire mass of solid basalt has been swept away 

 by the torrent, so that the former continuity of the stony current is 

 interrupted for several hundred yards, at a point about midway be- 

 tween its efflux from the cone and its termination. This implies a 

 long period of excavation. In another place, about one mile and a 

 half from St Nectaire, an old Roman bridge, still passable, having 

 two arches, each fourteen feet wide, spans a deep ravine, cut by the 

 Couze through the middle of the lava, which is here of columnar 

 structure. The bridge is supposed by French architects and anti- 

 quaries, to be of the date of about the fifth century ; yet the spring- 

 ing of the arches proves that, when it was erected, the ravine was 

 the same width as now. Nevertheless, while signs of denudation, such 

 as these, attest the vast amount of removal of hard rock since the 

 lava flowed and was consolidated, the contemporary cone of loose, 

 incoherent scoriae has stood in its exposed position at the very bottom 

 of a valley, entire and uninjured, the rain-water being instantly ab- 

 sorbed by the porous mass ; and no rill being allowed to collect on 

 its flanks. It is clear that if any flood of water had passed over 

 Auvergne, if any inundation had raised the Lake of Chambon 30 or 

 40 feet, it must have carried away the perishable cone. The lake 

 alluded to owes its origin to the damming up of the Couze by the 

 volcano, and by landslips which accompanied the eruption. 



But the most conclusive evidence, according to Mr Lyell, of the 

 remoteness of the period at which the cone and lava of Tartaret ori- 

 ginated, has yet to be set forth, and has only been distinctly brought 

 to light since he revisited Nechers in 1843, when the Abbe Croizet 

 pointed out to him a locality near the lower extremity of the great 

 current, where fossil bones of extinct animals had been discovered in 

 a meadow, between the base of the lava and the channel of the Couze, 

 now 10 feet lower in level than the lava. In company with Mr 

 Bravard, Mr Lyell explored the spot ; and they convinced themselves 

 that the bone-deposit passed under the lava, which here forms a mass 

 30 feet thick. Subsequent investigations not only confirm this view, 

 but have enabled Mr Bravard to obtain from beneath the stony cur- 

 rent a considerable number of additional osseous remains, referable 

 to the genera Equus, Sus, Tarandus, Cervus, Canis, Felis, Martes, 

 Putorius, Sorex, Talpa, Arvicola, Spermophilus, Lagomys, Lepus, 

 and, according to Mr Waterhouse, Cricetus or hamster, and others, 

 besides the remains of a frog, lizard, and snake, and the bones of 

 several birds. Mr Owen has examined some of these remains for 

 Mr Lyell, and recognizes among them the Equus fossilis and Tar- 

 andus priscus, both extinct species, occurring in the caves of Eng- 

 land, with the contents of which generally this assemblage of fossils 



