| OCR Text |
Show 96 MR. G. NEVILL ON THE [Feb. 1 7, of this immense deposit, one occasionally comes across some large boulder, around and below which I found these subfossil shells, often in great profusion, sometimes incrusted in the rock itself, but generally fortunately preserved in the soft red earth which fills the crevasses of these enormous blocks of stone, in a condition as fresh and perfect as on the day they were buried. There can, I think, be only one explanation of the really wonderful condition in which they are preserved: most undoubtedly the mollusks were at the time for the most part alive, actually living on the exact spots where they are still to be found. There they must have been suddenly buried as they lived, in situ, by the large deposits of this old Conglomerate, which one still finds heaped above them, of a thickness here of some 10 to 30 feet at least (oftentimes more), perhaps brought down by some enormous glacier from the high neigb-bouring Alps, by the St.-Louis gorge, which latter even may have been excavated as one finds it at present by this same action. I ought to add that these subfossils are but rarely to be found on the surface itself: to discover them one has to dislodge the larger stones and excavate the soil. Dr. J. Henry Bennet describes, in a most lucid way, this " Pleiocene conglomerate," in his interesting work 'Winter and Spring on the shores of the Mediterranean.' At page 39 he gives an account of the Geology of Menton, as also of the discovery of the bones of extinct wild beasts in these caves ; he there estimates the thickness of this " conglomerate " in the neighbourhood at from 600 to 800 feet. At page 45 he speaks of the extreme probability of glacial action ; but he is of the opinion of Dr. Niepce, of Nice, that it was formed under the sea, before the Glacial period, and afterwards thrown up in its present position. The first view is doubtless correct; but the last certainly can not have been the case in the instances of which I am treating. These mollusks, interred immediately under this conglomerate, undoubtedly have never been subjected, in the most remote manner even, to the action of the sea. I am quite of the opinion of Monsieur Bourguignat, that this conglomerate was formed very shortly after the Glacial period: the characters of these mollusks prove the climate to have been then very cold at the present sea-level; so the temperature must have been perfectly boreal on the summits of the neighbouring mountains. This would appear to be also the opinion of Prof. Issel (Appunti Paleont. Ann. Mus. Civ. Genova, vol. xiv. p. 11) ; he describes a similar deposit at Ventimiglia containing the bones of an extinct species of Elephant as belonging " al periodo Quaternario postglaciale." The following deposits or beds (A to D) of this Conglomerate, without doubt of one and the same age, contain these subfossil mollusks:- A. This was the only one of these deposits we could discover in France itself, all the others being in Italy: it is situated a few yards only from the frontier, a stone's throw from the " Pont St. Louis," about 50 metres above the sea, I should estimate; aspect nearly |
