184 HE. Andrews on Human Antiquities at Abbeville, &c. 
The valley of the Somme is over a mile and a half at the top, 
while the present river does not appear to exceed fifty feet in 
breadth. It is safe to say that the present stream spread over 
the whole valley, would not be half an inch deep, and making 
the irregular meandering of a shifting narrow stream, 
eroding this bank and now that. It is broad, forekaeney 
channels of communication in the soft chalk extending 
the upper to the lower, thus sketching out the lines of the sub- 
i ti 
verlying the gravel of the floor of the valley is a bed of 
peek about twenty-six feet in thickness. Mr. Boucher de Perthes 
with praiseworthy care sought for means to determine the 
age of this bed; but, as he was probably unacquainted wi 
yoo and the time required for it proportionately ete 
