E. Andrews on Human Antiquities at Abbeville, &c. 181 
and which are now connected by valleys of erosion extending 
from one to another. Upon the floor of the valley and extend- 
ing far up the slopes of the sides in many places are the famous 
gravel beds, which sometimes attain a thickness of 20 feet, 
Upon the lowland gravels rests a bed of peat about twenty-six 
feet thick, The discoveries in this valley have mostly been 
made by Mr, Boucher de Perthes, of Abbeville, who appears to 
have used great care to avoid mistakes, and to whose courtesy 
I am indebted for much valuable information, Boucher de 
Perthes finds in the gravels, as I have already said, the bones 
of the Elephas primigenius, the Rhinoceros tichorhinus, and 
other extinct animals in such connection with the bones of men, 
rude flint hatchets and other human relics, as to indicate that 
these great extinct pachyderms have been cotemporaneous with 
Man. They seém, however, to have become extinct at the time 
of the gravel deposit, for they are not found in the peat above. 
Boucher de Perthes inclines to the idea that the gravels were 
. the product of diluvial epoch, whose disturbances extermina- 
ted these animals, ae 
The European geologists frequently speak of the flint imple- 
ments of the gravel as found in the “drift.” American readers 
may need to be reminded that the gravel of the Somme is not 
genuine glacial drift, such as bears that name in America, but. 
simply a river deposit of more recent date. It is restri 
exclusively to the valley, and appears much like the gravel beds 
inking the river valleys of the western states, which also con- 
tain the bones of elephants, and are invariably found above 
the true drift. we eos | 
_ The question of the antiquity of these relics is one of great 
rs ogee for conceding their “pager tok there is little 
t, it is necessary to suppose that the aS Prvmigentus 
has lived later, or ree oe Se than is usually balan 
of the peat over it. 
Sir John phelind believes that the gravel was an extremely 
tion. He contends that it was maa y formed by the river, 
while it was slowly excavating the valley from the chalk, and 
In th its’ Ami I observed some facts which 
have an important bearing upon the question of time. ‘There 
1s evidence there that at the time the deposit was formed, blocks: 
of ice, or of mixed ice and frozen gravel, three or four feet m 
