but, following the outline of the pieces, there is a distinct "skin," or line of weathering, about one-sixteenth of an inch in depth, of a lighter colour, showing considerable lapse of time since the original stones were broken up.
In his 'Prehistoric Times,' Lord Avebury points out, on p. 329, with regard to flint flakes, that "those which have lain in siliceous or chalky sands are more or less polished, and have a beautiful glassiness of surface, very unlike that of a newly broken flint. In ochreous sand, especially if argillaceous, they are stained yellow, whilst in ferruginous sands and clays they assume a brown colour, and in some beds they become white and porcellanous." Now, these pieces are nearly all either almost white or light cream-colour, though some are about the colour of honey; whereas, had they lain in the red band of conglomerate since it was deposited, they would surely have been much darker. As a matter of fact, in nearly every instance in which a piece of the exterior of the original stones is found, on a flake, it is seen to be yellow or orange, sometimes brown, and this might give a clue as to where they came from.
There is a plateau gravel at Yenangyoung which contains large rounded stones, but we could not give much time to searching in it for pieces of flint; and, though I picked up a piece by the side of a cart-track, I did not at the time connect it with flint chips, and threw it away, and was unable to find it again. There is apparently no reason why the lumps of chert found on the plateau should be brought from any distance over a mile or two to the spot where they were broken up, and a further search in the neighbourhood would no doubt disclose the source of them. Mr. LaTouche has taken a few of the pieces for microscopic examination as to their composition.
As I have already mentioned, Mr. Oldham and others regard the pieces found by Dr. Noetling, which are now in the Geological Museum in Calcutta, as natural; but, as an answer to this, in the year 1897, Dr. Noetling published, in the 'Records of the Geological Survey of India,' vol. xxx. part 4, p. 242, an article entitled "Note on a worn Femur of Hippopotamus irravadicus, Caut. & Falc, from the Lower Pliocene of Burma," in which he figured and described a very fine unbroken femur, exhibiting at both ends "traces of a peculiar kind of grinding." He says he
