290 
THE GEOLOaiST. 
over any downs, across any chalk country, and not pick up, if you 
please, tons upon tons or cart-load upon cart-load ? If one sort, why 
not tlie other ? Is the proportion of flint-iraplements to unworked 
stones likely to be less in the disintegrated gravel-bed strewn over 
the soil than in the solid untouched stratum lying intact in the 
earth ? And if not, are we less likely to find flint-implements 
on t1ie surface of the soil than in the gravel-beds beneath it ? ^>Ve 
are sure we need not reply to these questions — our readers will have 
answered for themselves. 
7. Is it admissihle to suppose that products so similar were manu- 
factured, the one set at the commencement of the quaternary period, 
the other during the noio existing period, seeing that an immense inter- 
val of time separates the two epochs f-— Supposing the facts to be true, 
— but the facts are not stated by M. Gras, as already observed, — it 
might be so, if it be admissible to believe that small tribes or scat- 
tered individuals of a nation or race of m.ankind could live on after 
the destruction or distribution of the great bulk or mass of the nation 
or race. Just as some modern uncivilized tribes are presumed to be 
the descendants of once numerous and powerful peoples. Just as 
British and Celtic articles may be met with in Saxon and Eomau 
graves; just as medieval relics are still treasured in our houses, so 
may we always expect to find some relics of more ancient races 
amongst the relics of the more modern ones. Tlie case put however 
by M. Gras is a presumption, and it is futile to fill our pages with 
suppositions in reply to suppositious. "W^e go ou therefore to M. 
Gras' final summary : — 
" To all these difficulties one single fact only can be opposed, that, 
namely, of the absence of all apparent disturbance in the diluvium ; but 
this fact is not a peremptory reason, for it may be explained in a plausible 
manner. 
" Let us refer the manufacture of axes, which everything proves to have 
formerly been carried on in the valley of the Somme, to the origin of his- 
toric times. It is certain that the men occupied in this employment were 
not obliged to go very far to procure the first material that was necessary 
for them. By digging in the soil to a moderate depth, they found a great 
choice of flints ready to be cut. This was probably even the reason why 
this kind of industry sprang up in the country. The digging of flints might 
take place in two ways, by pits or by galleries. The first means M-as the 
most costly, since it was necessary to pass through the brown argillaceous- 
sandy diluvium before arriving at the flints, and because the removal of 
the rubbish must take place vertically. The digging by horizontal 
galleries op3ned on the side of the valle}', taking advantage of the steep 
banks, was evidently preferable. The excavation of these ancient galleries 
is so far from being unlikely, that even at the present day such are still 
made for the extraction of gravel. I have seen one at St. Acheul, and I 
