274 



THE WONDERS OF GEOLOGY. Lect. III. 



There are several incrusting springs in Auvergne, largely 

 impregnated with carbonic acid, which have deposited im- 

 mense quantities of calcareous tufa. These issue from 

 fissures in the granite and gneiss rocks that form the base of 

 the whole territory, and are spread over the volcanic foci 

 whence these mineral waters, in all probability, originate ; 

 numerous thermal springs also occur throughout the district. 



51. Successive Epochs of Mammalia. — The fossil 

 remains of mammalia found in the sedimentary deposits 

 of the volcanic region of Auvergne are very numerous, 

 and comprise many of the most ancient species of the Paris 

 basin, as well as those of existing ones. They are sepa- 

 rated by Mr. Lyell,* and other eminent observers, into three 

 groups ;— 



I. Mammalian remains from the fresh-water strata overlying the 

 granite ; these comprise bones of Palseotheria, Anoplotheria, and 

 other Cuvierian pachyderms, associated with extinct species of 

 Ehinoceros, Horse, Deer, &c. ; this is the most ancient group. 

 II. Bones of Mastodon, Hippopotamus, Elephant, Horse, Tapir, Elk, 

 Antelope, and many other terrestrial quadrupeds, all supposed 

 to be extinct forms ; associated with existing species of fresh- 

 water shells. These are from the lacustrine deposits, which are 

 separated from the above by ancient lava currents (basalt). 

 III. Fossil bones from the beds of sandy marl, and alluvial debris. 

 These are referable to small Rodents (Lagomys), and nearly fifty 

 species of other existing mammalia ; as Mouse, Squirrel, Hare, 

 Marten, Dog, Cat, &c. ; Hog, Ox, Deer, and Horse ; Frogs, 

 Lizards, Snakes, and Birds ; of the latter, even the eggs are occa- 

 sionally found. 



52. Summary of the geological phenomena of 

 Auvergne. — In the calcareous and siliceous limestones 

 of Auvergne, and their associated laminated marls, 

 gypsum, lignite, and conglomerate, we have a general 

 analogy with the older fresh-water tertiary formations 

 of Paris ; the shells and plants being similar, and the 

 quadrupeds of the same genera. And if we suppose the 



* See Proceedings of the Geol. Soc. 1845, p. 75. 



