The most notable places in the neighbourhood of Abbeville, where the gravel has been extensively excavated, are at the spot where is now the Champ de Mars, the pit near the Moulin Quignon, and that near the Porte St. Gilles; but the beds of gravel are spread over a large area, and are said to be continuous from the Moulin Quignon on the south-east of the town, and about ninety feet above the level of the river Somme, to the suburb of Menchecourt on the north-west of Abbeville, where the beds assume a much more arenaceous character, and where sand has been dug in immense quantities at a level but little more than twenty feet above that of the Somme.
At St. Roch, a suburb of Amiens, the deposit is also at a low level, like that at Menchecourt, and at both places large quantities of teeth and bones of the Elephas primigenius, Rhinoceros tichorhinus, and other extinct animals, have been found.
In another locality, on the opposite side of Amiens to St. Roch, at the pits near the seminary of St. Acheul, the drift occurs at a higher level, viz. about ninety feet above the river Somme at that part of its course, or about one hundred and sixty feet above the sea. The depth of the beds, which consist of brick earth, sand, and gravel, arranged in layers of variable thickness, but with some approach to stratification, is here from twenty to twenty-five feet.
The following section was taken by Mr. Prestwich,[1] showing the beds in their descending order:—
- 1. Brown brick-earth, loam, and clay, with an irregular bed of flint gravel near its base. No organic remains10 to 15 feet.
(Divisional plane between 1 and 2, very uneven and indented.)
- 2. Whitish marl and quartzose sand, with small chalk grit. Land and fresh-water shells (Lymnæa, Succinea, Helix, Bithinia, Planorbis, Pupa, Pisidium, and Ancylus, all of recent species,) are common; mammalian bones and teeth are occasionally found.2 to 8 feet.
- 3. Coarse subangular gravel, white, with irregular ochreous and ferruginous seams, and with tertiary flint pebbles and sandstone blocks. Remains of shells similar to those last mentioned in patches of sand; teeth and bones of the elephant, and of a species of horse, ox, and deer, generally in the lower part of the bed. It reposes on an uneven surface of chalk.6 to 12 feet.
- ↑ Proceedings of the Royal Society, May 26, 1859.
