134 SECTION OF GRAVEL AT ST. ACHEUL. chap. viii. 



especially as many tusks of a hippopotamus have been ob- 

 tained from the gravel of St. Eoch, — some of these recently 

 by Ml". Prestwich; while M. Gamier, of Amiens, has pro- 

 cured a fine elephant's molar from the same pits, which Dr. 

 Falconer refers to Elephas antiquus (see fig. 19, p. 133.) Hence 

 I infer that both these animals coexisted with man. 



The alluvial formations of Montiers ai'e very instructive in 

 another point of view. If, leaving the lower gravel of that 

 place, which is topped with loam or brick-earth (of which 

 the ujiper portion is about thirty feet above the level of the 

 Somme), we ascend the chalk}'^ slope to the height of about 

 eighty feet, another deposit of gravel and sand, with fluvia- 

 tile shells in a perfect condition, occurs, indicating most 

 clearly an ancient river-bed, the waters of which ran habitu- 

 ally at that higher level before the valley had been scooped 

 out to its present depth. This superior deposit is on the 

 same side of the Somme, and about as high, as the lowest 

 part of the celebrated formation of St. Aeheul, two or three 

 miles distant, to which I shall now allude. 



The terrace of St. Aeheul may be described as a gently 

 sloping ledge of chalk, covered with gravel, topped as usual 

 with loam or fine sediment, the surface of the loam being 100 

 feet above the Somme, and about 150 above the sea. 



Many stone coffins of the Gallo-Roman period have been 

 dug out of the upper portion of this alluvial mass. The 

 trenches made for burying them sometimes penetrate to the 

 depth of eight or nine feet from the surface, entering the 

 upper part of No. 3 of the sections Nos. 21 and 21 a. They 

 prove that when the Romans were in Gaul they found this 

 terrace in the same condition as it is now, or rather as it was 

 before the removal of so much gravel, sand, clay, and loam, 

 for repairing roads, and for making bricks and potter3^ 



In the annexed section, which I observed during my last visit 

 in 1860, it will be seen that a fragment of an elephant's tooth 



