It still remains to inquire whether man may have made his appearance at the close of the pliocene or in the early stages of the pleistocene, before the full development of the glacial conditions of that period. Perhaps the most important indications of this kind are those adduced by Dr. Mourlon, of the Geological Survey of Belgium,[8] from which it would appear that worked flints and broken bones of animals occur in deposits, the relations of which would indicate that they belong either to the base of the pleistocene or close of the pliocene. They are imbedded in sands derived from eocene and pliocene beds, and supposed to have been _remanié_ by wind action. With the modesty of a true man of science, Mourlon presents his facts, and does not insist too strongly on the important conclusion to which they seem to tend, but he has certainly established the strongest case yet on record for the existence of tertiary man. With this should, however, be placed the facts adduced in a similar sense by Prestwich in his paper on the worked flints of Ightham.[9] [8] _Bulletin de l'Académie Royale de Belgique_, 1889. [9] _Journal of the Geological Society_, London, May 1889. Should this be established, the curious result will follow that man must have been the witness of two great continental subsidences, or deluges, that of the early pleistocene and the early modern, the former of which, and perhaps the latter also, must have been accompanied with a great access of cold in the northern hemisphere. It seems, however, more likely that the facts will be found to admit of a different explanation. Every reader of the scientific journals of the United States must be aware of the numerous finds of 'palæolithic' implements in 'glacial' gravels, indicating a far greater antiquity of man in America than on other grounds we have a right to imagine. I have endeavoured to show, in a work published several years ago,[10] how much doubt on geological grounds attaches to the reports of these discoveries, and how uncertain is the reference of the supposed implements to undisturbed glacial deposits, and how much such of the 'palæoliths' as appear to be the work of man resemble the rougher tools and rejectamenta of the modern Indians. But since the publication of that work, so great a number of 'finds' have been recorded, that despite their individual improbability, one was almost overwhelmed by the coincidence of so many witnesses. Now the bubble seems to have been effectually pricked by Mr. W. H. Holmes, of the American Geological Survey, who has published his observations in the _American Journal of Anthology_ and elsewhere.[11] [10] _Fossil Man_, London, 1880. [11] _Science_, November 1892; _Journal of Geology_, 1893. [Illustration: SECTION AT TRENTON, ON THE DELAWARE, SHOWING THE RELATION OF THE STONE IMPLEMENTS TO THE GLACIAL (?) GRAVELS (after Holmes)]