pheric influences, and have been subjected to chemical changes and the friction of sand and water. These causes produce the characteristic "patina," which distinguishes genuine flint implements, and which varies greatly according to the conditions under which the objects have remained. It is of very different colors, but has never been successfully imitated by artificial means. Many of the implements also, like mine, are marked by a beautiful moss-like deposit of oxide of manganese, called "dendrites," which is an additional guarantee of their genuineness, as it is only produced by a long lapse of time. In the gravel-pits in the neighborhood of Paris, on both banks of the Seine, in many visits ranging over several years, I have been able to procure a large number of worked flints, together with the usual fossil bones that accompany them. So, too, in similar excavations at the Ponte Molle, near Rome, at a long distance from the present bed of the Tiber, and far above the limit of any possible inundation now, I have obtained numerous specimens both of flints and bones.
To go thoroughly over the arguments of the geologists, by which the very great antiquity of such Quaternary deposits with their contents has been established, would require more space than is at my command. I will simply state a few facts, leaving others to draw their own inferences from them. Implements of the St. Acheul type have been found in place at the bottom of undisturbed gravel beds more than thirty feet deep, both at Abbeville and at Amiens, and in the former locality peat-beds have been subsequently formed in the more deeply excavated portion of the valley more than thirty feet in thickness. Now, whatever may be the lapse of time needful for the accumulation of such a mass of peat as this, it is all posterior in date to the ancient implement-bearing gravels. At Amiens Roman graves have been found in the superficial deposits at about the present level of the river, and far below that of the Quaternary gravels, showing that more than fifteen hundred years have produced scarcely any change in the configuration of the valley, so far as its depth is concerned. So, too, on the top of Milford Hill, in the neighborhood of Salisbury, England, are found Quaternary gravels containing implements of the St. Acheul type. This hill is cut off from the main spur to which it belongs by a transverse valley, which proves that, at the time when the gravel was deposited there, such a depression could not have existed, as in that case the water would have flowed along the valley, and not left its contents on the top of the hill. On each side of the hill is also a similar valley, which, for the same reason, could not have been there when the gravel was deposited. Thus the top of the hill once formed the bottom of the bed of a river flowing along a valley whose sides have now entirely disappeared, and in their place a new valley has been excavated on each side to the depth of one hundred feet.
That these Quaternary gravels can not be owing to any sudden
