CHAPTER 7. — PEAT AND PLEISTOCENE ALLUVIUM OF THE VALLEY OF THE SOMME.

     Geological Structure of the Valley of the Somme and of the
        surrounding Country.
     Position of Alluvium of different Ages.
     Peat near Abbeville.
     Its animal and vegetable Contents.
     Works of Art in Peat.
     Probable Antiquity of the Peat, and Changes of Level
        since its Growth began.
     Flint Implements of antique Type in older Alluvium.
     Their various Forms and great Numbers.