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Lower Tertiary deposits separate tliem, 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 that district the original flint-implement stratum, 

 identical with that of the valley of the Somme, is found in the 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 XCundesley. 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 Mlephas meridionalis and 

 _ZT, antiquus, and lastly than the phenomena of striation, groovings, and 

 polished surfaces of the northern regions, whether in the British Islands 

 or in Scandinavia. The fauna which 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 — ■ 

 JElephas pri mi 'genius, _ZT. antiquus, Rhinoceros tichorhinus, Wppopatam us 

 major, Cervus tarandus, C. megaceros, Bos primigenius, JB. moscliatus, 

 JEqtms fossilis, Felis spelma, Hpcena spelcca, Ursus spelmus, etc. ; that is, 

 precisely the association of species which we find in the fluvio-marine de- 

 posits of ZMenchecourt. 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 AT en che court of the Corbicula consobrina or 

 fturninalis, 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. 



2s"ow 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 palseontologieal 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 the 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 reality, 

 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 31. d'Archiac, 

 with M. Woraaae, 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 antehistoric, the arms or instruments of 

 which belong to a more or less barbaric state, the age of which comes up 



