In the valley of ihe Garonne, the Pyrenean drift is the geological or synchronal equivalent of the diluvium of the Seine and of the diluvial deposits of Amiens, Abbeville, &c., because it is in these alluvial beds, that are found the remains of Elphas primigenius, Rhinoceros tichorinus, and other species regarded as characteristic of the diluvium.
But this phenomenon of torrential recrudescence, which has produced the diluvium, and whose cause must be sought in a sudden return to regional conditions of extreme temperature, has been manifested, only to a comparatively very trifling extent, in all the valleys descending from the plateau of Lanemézan. It is not astonishing therefore, to find that the sepulchre of Aurignac, if it existed at that time, should not have suffered any damage from the effect of the great floods of the period, seeing that, from its comparative altitude, it was placed beyond their reach.
I would, nevertheless, go farther, and say that viewed simply under the paæontological relations manifested in it, the sepulchre of Aurignac claims a very high comparative antiquity. In fact, the Great Cave Bear, which we there behold evidently cotemporary with man, has not, so far as I know, yet been found in France in the diluvium. It is true, that it has been mentioned in a list which has several times been reproduced, of the fossil Mammals discovered in the diluvial beds of Abbeville; but I have in vain tried to get at the source of the methodical determination upon which this statement rests, and from all that I have seen of its fossil remains the Bear, either from the valley of the Somme, or from the environs of Paris, belongs to a species, or to more than one species, very certainly distinct from Ursus spelæus. In the centre of France, and in England, all the remains of the latter species, not found in caverns, come from deposits, regarded by geologists as more ancient than the diluvium.
It will, doubtless, be objected to this, that the remains of Ursus spelæus occur very abundantly in most of the caverns of the continent, and even in some of those in England; but, at the same time, it must not be forgotten that the date of the filling of these caverns is evidently to be placed beyond the epoch assigned by geologists to the diluvial phenomena, because in several of these caverns, at any rate, the remains of Mammals are met with, which are sometimes included in the lists of species referred to the latter phases of the tertiary period.
We see then, that if we rely solely upon the consideration of the palæontological concomitances, the result we should arrive at would be, that the sepulchre of Aurignac should be referred, together with all the circumstances accompanying it, to an epoch anterior to the diluvium properly so termed. In confining the force of this remark simply within the limits of its inductive value, I do not think I am losing sight of the reserve with which new propositions should be introduced, when they as yet repose only on negative observations.
