t 479 ] 



LXIII. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 



[Continued from p. 403.] 



November 6, 1867.— Warington W. Smyth, Esq., M.A., F.R.S., 



President, in the Chair. 



THE following communication was read : — 

 " On the Amiens Gravel." By A. Tylor, Esq., F.L.S., F.G.S. 



The author referred first to the prevalent views respecting the 

 gravels of the Valley of the Somme, namely, (1) that there are two 

 deposits cf distinct age — the upper and the lower valley- gravels ; 

 (2) that the former of these is the older; (3) that the Valley of the 

 Somme has been excavated to the depth of 40 or 50 feet since its 

 deposition ; (4) that both gravels contain bones of extinct animals, 

 and implements of human manufacture, the lower gravels, however, 

 containing the greater number of species of Mollusca, and the upper 

 the greater number of flint implements ; and (5) that the height 

 (70 feet) of the gravels at St. Acheul above the present level of the 

 Somme is much beyond the limit of floods, and that, therefore, they 

 could only have been deposited before the river-channel was cut 

 down to its present level. He then pointed out that the general 

 effect of these views is to refer back the remains of man found at St. 

 Acheul to an indefinite date, separated from the historical period by 

 an interval during which the valley was excavated. 



In former papers Mr. Tylor stated his belief that the upper and 

 lower valley- gravels of the Somme are continuous and of the same 

 age, which he considered to be close to the historical period. In 

 this paper he stated facts which appeared to him to demonstrate the 

 truth of his views, and described a number of sections near Amiens, 

 in which the levels were laid down from an exhaustive survey by 

 M. Guillom, Chief Engineer of the Northern Railway of France. 



The conclusions he had thus been able to arrive at are the follow- 

 ing : — (1) That the surface of the chalk in the Valley of the Somme 

 had assumed its present form prior to the deposition of any of the 

 gravel or loess now to be seen there ; (2) that the whole of the 

 Amiens valley-gravel is of one formation, of similar mineral cha- 

 racter, contains nearly similar organic remains, and belongs to 

 a date not much antecedent to the historical period ; (3) that the 

 gravel in the valley of the Somme at Amiens is parti)'" composed of 

 debris brought down by the river Somme and by the two rivers the 

 Celle and the Arve, and partly of material from the higher grounds 

 washed in by land-floods ; (4) that the Quaternary gravels of the 

 Somme are not separated into two divisions by an escarpment of 

 chalk parallel to the river, as has been stated ; (5) that the evidence 

 of river-floods extending to a height of at least 80 feet above the 

 present level of the Somme is perfectly proved by the gradual slope 

 and continuity of the gravels deposited by them ; and (6) that many 

 of the Quaternary deposits in all countries, clearly posterior to the 

 formation of the valleys in which they lie, are of such great dimen- 



