Page:Geological Evidences of the Antiquity of Man.djvu/134

116 as Mr. Prestwich has suggested, for cutting holes in the ice both for fishing and for obtaining water, as will be explained in the 8th chapter when we consider the arguments in favour of the higher level drift having belonged to a period when the rivers were frozen over for several months every winter.

When the natural form of a chalk-flint presented a suitable handle at one end, as in the specimen, fig. 10, that part was left as found. The portion, for example, between b and c has probably not been altered; the protuberances which are fractured having been broken off by river action before the flint was chipped artificially. The other extremity, a, has been worked till it acquired a proper shape and cutting edge. Many of the hatchets are stained of an ochreous-yellow colour, when they have been buried in yellow gravel, others have acquired white or brown tints, according to the matrix in which they have been enclosed.

This accordance in the colouring of the flint tools with the character of the bed from which they have come, indicates, says Mr. Prestwich, not only a real derivation from such strata, but also a sojourn therein of equal duration to that of the naturally broken flints forming part of the same beds.

The surface of many of the tools is encrusted with a film of carbonate of lime, while others are adorned by those ramifying crystallisations called dendrites (see figs. 11—13), usually consisting of the mixed oxyds of iron and manganese, forming extremely delicate blackish brown sprigs, resembling the smaller kinds of sea weed. They are a useful test of antiquity when suspicions are entertained of the workmen having forged the hatchets which they offer for sale. The most general test, however, of the genuineness of the implements obtained by purchase is their superficial varnish-like or vitreous gloss, as contrasted with the dull aspect of freshly