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Updated: April 30, 2025
This period was followed by other dilatations of the same veins, and the introduction of other sets of mineral deposits, as well as of pebbles of the basaltic lavas of Auvergne, derived from superficial alluviums, probably of Miocene or even Older Pliocene date.
In reference to this point, I may observe that although I was not able to fix with precision the exact bed in the volcanic mountain from which the rock containing the human bones was taken, M. Felix Robert has, nevertheless, after studying "the volcanic alluviums" of Denise, ascertained that, on the side of Cheyrac and the village of Malouteyre, blocks of tuff frequently occur exactly like the one in the museum.
So extensive have been the discoveries of the works of man buried with the bones of the Elephas primigenius and of cavern-bears and extinct hyenas, that we are forced to recognize the fact of the coexistence of man with those ancient animals, for the occurrence of deposits containing the bones of the two cannot any longer be regarded as doubtful; and certainly stone tools fashioned by man have been found so widely spread in the ancient alluviums and deposits of the post-Pliocene age, as to remove all doubt of the fact, and to destroy the objection that they might be local accidents of an equivocal character.
That a great many veins communicated originally with the surface of the country above, or with the bed of the sea, is proved by the occurrence in them of well- rounded pebbles, agreeing with those in superficial alluviums, as in Auvergne and Saxony. Marine fossil shells, also, have been found at great depths, having probably been ingulfed during submarine earthquakes.
The pebbles therefore in the older gravels are exclusively constituted of granite and other aboriginal rocks; and afterwards, when volcanic vents burst forth into eruption, those earlier alluviums were covered by streams of lava, which protected them from intermixture with gravel of subsequent date.
The whole of them were at first confounded with the superficial alluviums of Europe; and it was long before their real extent and thickness, and the various ages to which they belong, were fully recognised.
"Because it is well known that animal life only existed on earth during the secondary period, when the sedimentary soil was formed by the alluviums, and thus replaced the hot and burning rocks of the primitive age." "I have listened to you earnestly and with patience, Harry, and I have a simple and clear answer to your objections: and that is, that this itself is a sedimentary soil."
For this reason it would be unreasonable to hope that we should ever be able to account for all the alluvial phenomena of each particular country, seeing that the causes of their origin are so various. Besides, the last operations of water have a tendency to disturb and confound together all pre-existing alluviums.
The early geologists gave to all the crystalline and non-fossiliferous rocks the name of Primitive or Primary, under the idea that they were formed anterior to the appearance of life upon the earth, while the aqueous or fossiliferous strata were termed Secondary, and alluviums or other superficial deposits, Tertiary.
In the course of ages, a new system of valleys was excavated, so that the rivers ran at lower levels than those at which the first alluviums and sheets of lava were formed.
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