LUBBOCK ON THE ANTIQUITY OF MAN. 263 



of tlie river, and gradual excavation of the valley, which, by supplying 

 the floods vnth a lower bed, left the waters at this height with a gra- 

 dually diminishing force and velocity. 



The upper part of the section at St. Acheul consists of brick 

 earth, passing below into angvdar gi^avel, while between this and the 

 underlying sandy marl is sometimes a small layer of darker brick 

 earth. These beds, however, vary much even in adjoining sections. 

 Tiikcn as a whole they are regarded by Mr. Prestwich as the repre- 

 sentatives of that remarkableloamy deposit which is found overlying 

 the gravels in all these valleys of Northern France, and which, as the 

 celebrated " loess" of the Eliine, attains a thickness of 300 feet. The 

 greatest development of it which I have seen was in a pit in the Eue 

 de la Chevalerie, near IvTy, where it was twenty-two feet thick, 

 some of which however may have been reconstructed loess brought 

 down by rain from the higher ground in the immediate neigh- 

 bourhood. 



Assuming that this loess is composed of fine particles deposited 

 from standing or slowly moving waters, we might be disposed to 

 wonder at not finding in it any traces of vegetable remains. We 

 know, however, from the arrangement of the nails and hasps that in 

 some of the St. Acheul tombs wooden coffins were used, while the 

 size of the nails shows that the planks must have been tolerably thick ; 

 yet in these cases every trace of wood has been removed, and not 

 even a stain is left to indicate its presence. 



Such is a general account of those gravel pits which lie at a height 

 of from 80 to 150 feet abo^e the present water level of the valleys, 

 and which along the Somme are found in some places even at 

 a height of 200 leet. 



Let us now visit some of the pits at the lower levels. At about 

 thirty feet lower, as for instance at Menchecourt, near Abbeville, 

 and at St. Eoch, near Amiens, Avhere the gi-avels slope from a height 

 of about sixty feet down to the valley, we find almost a repetition 

 of the same succession ; coarse subangular gravel below, finer ma- 

 terials above. So similar, indeed, are these beds to those already 

 described, both in constitution and in the animal remains they 

 contain, that it Avill be unnecessary for me to give any farther 

 description of them. 



Finally, the lowest portion of the valley is at present occupied 

 by a bed of gravel, covered by silt and peat, which latter is in 

 some places more than twenty feet thick, and is extensively 

 worked for fuel. These strata have afforded to the antiquaries of 

 the neighbourhood, and especially to M. Boucher de Perthes, a rich 

 harvest of interesting relics belonging to various periods. The depth 

 at which these objects are fomid has been carelully noted by M. 

 Boucher de Perthes. 



" Prenant," he says, " pour terme moyen du sol de la vallee, une 

 " hauteur de 2 metres audessus du niveau de la Somme, c'est a 30 a 

 " 40 centimetres de la surface qu'on rencontre le plus abondamment 



