DISCOVERIES AT AMIENS. 
153 
or by the action of acids, as they lay in the gravel. They 
are most commonly stained of the same ochreous color as 
the flints of the gravel in which they are imbedded. Occa¬ 
sionally their antiquity is indicated not only by their color 
but by superflcial incrustations of carbonate of lime, or by 
dendrites formed of oxide of iron and manganese. The edges 
also of most of them are worn, sometimes by having been 
used as tools, or sometimes by having been rolled in the old 
river’s bed. They are met with not only in the lower-level 
gravels, as in No. 3, Fig. 87, but also in No. 4, or the higher 
gravels, as at St. Acheul, in the suburbs of Amiens, where 
the old alluvium lies at an elevation of about 100 feet above 
the level of the river Somme. At both levels fluviatile and 
land-shells are met with in the loam as well as in the gravel, 
but* there are no marine shells associated, except at Abbe¬ 
ville, in the lowest part of the gravel, near the sea, and a few 
feet only above the present high-water mark. Here with 
fossil shells of living species are mingled the bones of Ele- 
phas prwugenius and jE antiqims^ Rhinoceros tichorhinics^ 
Hippopotamus^ Felis spelcea^ Hyoena speloea^ reindeer, and 
many others, the bones accompanying the flint implements 
in such a manner as to show that both were buried in the 
old alluvium at the same period. 
■ Nearly the entire skeleton of a rhinoceros was found at 
one point, namely, in the Menchecourt drift at Abbeville, 
the bones being in such juxtaposition as to show that the 
cartilage must have held them together at the time of their 
inhumation. 
The general absence here and elsewhere of human bones 
from gravel and sand in which flint tools are discovered, 
may in some degree be due to the present limited extent of 
our researches. But it may also be presumed that when a 
hunter population, always scanty in numbers, ranged over 
this region, they were too wary to allow themselves to be 
overtaken by the floods which swept away many herbivor¬ 
ous animals from the low river-plains where they may have 
been pasturing or sleeping. Beasts of prey prowling about 
the same alluvial flats in search of food may also have been 
surprised more readily than the human tenant of the same 
region, to whom the signs of a coming tempest were better 
known. 
Inundation-mud pf Rivers.—Brick-earth.—Fluviatile Loam, 
or Loess. —As a general rule, the fluviatile alluvia of differ¬ 
ent ages (Nos. 2, 3, 4, Fig. 87) are severally made up of coarse 
materials in their lower portions, and of fine silt or loam in 
their upppr parts. For rivers are constantly shifting theix* 
