LECTUEE X. 285 



" Wtat lias been said of the caverns of Liege^ and what we 

 shall sav^ is quite sufficient to answer satisfactorily the other 

 part of the question. 



" From the facts before us we cannot^ in the present state 

 of our knowledge^ but assume, that the flint hatchets of the 

 environs of Amiens and Abbeville are situated in undisturbed, 

 essentially quaternary beds, along with the bones of extinct 

 species, and^ unless peculiar circumstances come to light, we 

 must also assume that the jaw of Moulin-Quignon dates from 

 that period. 



"We must here touch upon a point, hitherto but little 

 noticed; I mean the determination of the age of these de- 

 posits, or rather of the rank they occupy in the quaternary 

 series. To what time of this period, disturbed by so many 

 phenomena, do these beds correspond ? 



" This determination appears to us at present easy, unless 

 we search for comparisons in the south [in the Alpine dilu- 

 vium, 0. v.], where they do not occur, and where we cannot 

 estimate their value ; but when we proceed to the north-east, 

 the Netherlands, where the whole quaternary series stands in 

 its true relation to the upper tertiary strata, both above and 

 below the present sea level, or still better, when we proceed 

 more northwards to the eastern counties of England. 



" The deposits of clayish, sandy or flinty conglomerates, 

 which are found in the basin of the Somme and in all the small 

 brook-valleys which run from the Oise direct to the sea, all lie 

 directly upon the chalk, and, excepting those cases where 

 lower tertiary formations interpose, we see no intermediate 

 deposit which may enable us to estimate the immense time 

 which must have elapsed between those deposits which are at 

 present superimposed upon each other. 



" But on the other side of the Channel, the flint hatchets, 

 which are identical with those of the Somme valley, lie in fresh 

 water strata deposited in the cavities of the boulder clay. This 

 is shown by the sections in the environs of Hoxne in Suffolk, 

 Bedford, and the coast of Norfolk, near Mundesley. These 

 sections prove that the fresh-water formations are more recent 

 than the quaternary marine deposits of England, Scotland, and 



