ing pit some minor variations in the nature and thickness of the superimposed deposits may be seen, there is yet a general approach to uniformity in the series. The only stratum of which the relative age is somewhat doubtful, is the gravel marked a, underlying the peat, and resting on the chalk. It is only known by borings, and some of it may be of the same age as No. 3; but I believe it to be for the most part of more modern origin, consisting of the wreck of all the older gravel, including No. 3, and formed during the last hollowing out
Fig. 16
Section of fluvio-marine strata, containing flint implements and bones of extinct mammalia, at Menchecourt, Abbeville.[1]
2 Calcareous loam, buff-coloured, resembling loess, for the most part unstratified, in some places with slight traces of stratification, containing freshwater and land shells, with bones of elephants, &c.; thickness about fifteen feet.
3 Alternations of beds of gravel, marl, and sand, with freshwater and land shells, and in some of the lower sands, a mixture of marine shells; also bones of elephant, rhinoceros, &c., and flint implements; thickness about twelve feet.
a Gravel underlying peat, age undetermined.
b Layer of impervious clay, separating the gravel from the peat.and deepening of the valley immediately before the commencement of the growth of peat.
The greater number of flint implements have been dug out of No. 3, often near the bottom, and twenty-five, thirty, or even more than thirty feet below the surface of No. 1.
