FORETGK ITs'TELLIGENCE. 
431 
Lower Tertiary deposits separate tLem, and we perceive no intermediate 
stratum sufficiently characterized to admit our appreciating the immen- 
sity of time which elapsed before these recent sediments were super- 
posed. But beyond tliat district the original flint-implement stratum, 
identical with that of the valley of the Somme, is found in tlie lacustrine 
beds which have succeeded the partial scooping out (ravinement) of the 
till or boulder-clay. The evidence of these relations has been given by 
the sections at Hoxne,in Suffolk, the valley of the Lark, at Bedford, etc., 
compared with those of Mundesley, on the Norfolk coast. These have de- 
monstrated to us that the lacustrine beds are more recent than the marine 
quaternary deposits of England, Scotland, and Ireland, and still more so 
than the Norfolk Crag, the masses of bones of Ehphas meridionaUs and 
E. antiquus, and lastly than the plienoraena of striatiou, groovings, and 
polished surfaces of the northern regions, whether in the British Islands 
or in Scandinavia. The fauna wliich characterizes these sediments, where 
industrial products for the first time appear, consists of fluviatile and ter- 
restrial mollusca, — which, with two or three exceptions, still live in the 
district, — and of pachydermatous mammalia, ruminants, and carnivora — 
Elephas primi genius, E. antiquus. Rhinoceros tichorhimis. Hippopotamus 
major, Cervus tarandus, C. megaceros. Bos primigenius, B. nioschatus, 
Equus fossilis, Felis spelcea, Jlycena spelcea, Ursus spelceus, etc. ; that is, 
precisely the association of species which we find in the fluvio-marine de- 
posits of Menchecourt, in the sand and gravel drift deposits {terrains de 
transport) of other localities around Abbeville, Amiens, as well as in the 
valley of the Oise, in the environs of Chauny, etc. The analogy of these 
faunas, between one part and the other of the region, is rendered still more 
striking by the presence at Menchecourt of the Corhicula consobrina or 
Jiuminalis, so characteristic of the same horizon from Grays Thurrocks, on 
the left bank of the Thames, as far as the neighbourhood of Hull, on the 
borders of the H umber, and which has been observed at the same horizon 
in well-sinkings at Ostend. 
Now the debris of this fauna of vertebrates and invertebrates has been 
buried since the spreading of the great deposits of sand, clay, and rolled 
pebbles, which extends from the east and south parts of England, and 
to which succeeds also, in some parts of the Continent, an argillaceous 
sand analogous to the ancient alluvium. If with these known stratigra- 
phical and palaeontological divisions on the other side of the straits, we 
specially compare those of the valley of the Somme, we shall be led to 
regard the quaternary deposits of the latter as not more ancient than the 
lacustrine beds of England, as contemporary with those that beyond the 
Channel contain the fauna of great extinct mammalia which lived towards 
the middle of the Quaternary epoch. The deposits of tlie valley of the 
Somme, like those of the basins of the Oise, more recent than the boul- 
der-clay {argile a blocs), than the crag of Norfolk, represent, in reahty, 
only the phenomena which preceded the second glacial period. Thus on 
the one part the comparison of these deposits with those of the neigh- 
bouring departments to the east, and where the stratigraphical relation- 
ships are better marked, permits a statement of the period to which they 
belong ; on the other hand, their comparison with those of Belgium, Hol- 
land, and England, reveals their true place or exact horizon in the series 
of sediments of this age. " We distinguish thus," says M. d'Archiac, 
" with M. Worsaae, two ages of stone ; one anterior to the last quater- 
nary deposits, or antediluvian, characterized by the most rudely worked 
flints ; the other, posterior or anteJustoric, the arms or instruments of 
which belong to a more or less barbaric state, the age of which comes up 
