116 FLINT IMPLEMENTS IN VALLEY OF THE SOMME. CHAP. vn. 



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 ex 

 tremity, 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 imple 

 ments obtained by purchase is their superficial varnish-like 

 or vitreous gloss, as contrasted with the dull aspect of freshly 



* Philosophical Transactions, 1861, p. 297. 



