196 Hints for the Formation of 
CHAP. VIII. 
Observations to be made on Foiled Pebbles . 
1. The nature and size of those found in any particu- 
lar district, 
% To examine, above all, whether there is any kind 
which may be considered as peculiar to that district, or 
which may be proper to characterise it ; or even, whe- 
ther the absence of any kind or class might not be suffi- 
cient to form that character. 
8. Whether those found on the borders of any river 
might be considered as having been thrown up by that 
river, or whether it only exposed them to view by wash- 
ing away the soil which it watered. 
4* After establishing the character of the pebbles of a. 
certain district, one might follow, as it were, their traces, 
and form conjectures both respecting their origin and the 
route they have pursued. 
5. The increase of their size will show that they ap- 
proach their origin, or vice versa ; but care must be ta- 
ken that other veins of pebbles crossing the former may 
not conceal the course of those which you are tracing 
out. 
6. A consideration of the pebbles, and still more that 
of rolled blocks, or, at least, such as are foreign to the 
soil which bears them ; of the height at which they are 
found, and of the large valleys opposite to their present 
situation, may afford some indications of the direction, 
size, and force of the currents produced by the grand re- 
volutions of the earth. 
7. A consideration of those blocks which rest on solid 
rock, and which seem still to occupy the place where 
they were deposited, may, by the state of these rocks, 
give an idea of the time elapsed since their arrival. 
8. How far can the transportation of these great blocks 
