same level, a little to the west. On the edge of the Saveuse 
valley, 400 yards south of O, the loess was only from 1 to 2 feet 
thick, At St.-Acheul it was only 5 or 6 feet thick; but there 
were intermediate beds of marl and sand between the true loess 
and the true gravel there. 
There seems to be a line of thicker brick-earth or loess run- 
ning south and north between the lines OP and NQ. This 
would indicate that the water was more tranquil at that point, 
Such differences in currents are very apparent in rivers at the 
present time; and the warp of our rivers approaches very nearly 
to the character of loess. The fossiliferous gravels at St.-Acheul 
extend to a height of 70 feet above the river, or much higher 
than the corresponding fossiliferous gravels in the valley of the 
Thames. The shells are found in false-bedded fine sand, and 
_ hot in clay, at St-Acheul, and in precisely the same condition 
as at Crayford 
. 
The chalk is capped in some places with Tertiary sands at 
‘Crayford; but the gravel lies on the concavities of chalk and 
Sand quite indifferently. ‘ 
| €river Cray falls into the Thames much as the river 
Arve falls into the Somme, The Crayford gravel is 100 feet 
thick, and confined to a space between two valleys, the eastern 
Valley occupied by the river Cray, and the other and western 
a dry valley, like that southwest of St.-Acheul. 
Ey 
a 
a | 
: 
[4] 
= 
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TR 
- 12 and 13, and fig. 8 below), and I propose to make some 
Temarks upon the peculiarities of deposition to be observed 
there at some future time. I will now only observe that the 
‘acter of the sections, I think, clearly shows us that a large 
whole tuantity of chalk-detritus is about one-eighth of the 
_ Whole mass of gravel and loess, and makes the yepe 
A, Tylor on the Amiens Grovel. er poe 
