4 26 
The Hon. Mr. Strangways on the 
appears to form entire hills, as at Penty, &c. It is usually thickest 
in the vallies, or on the flat summits of some of the hills. Its com- 
position, much as it differs in different places, may be considered 
twofold ; first, as the debris of rocks upon which, or in the neigh- 
bourhood of which, it is accumulated ; secondly, as that of a set of 
rocks totally foreign to the country, the analogies of some of which 
have been recognized in situ at a vast distance, while others remain 
yet to be identified. 
The principal foreign ingredient is a granitic sand, from which it 
is seldom perfectly free. In some parts, particularly on the right 
bank of the Neva, it is a pure granitic gravel or sand, partly derived 
from the same source as the primitive boulders themselves, and 
deposited at the same time with them ; partly from the daily decay 
of those blocks from the action of the weather. This character 
becomes stronger on approaching the borders of Finland. 
Parts of the country north of the Neva, and the environs of 
Peterhof and Pavlovsk, are covered with a superficial sand derived 
principally from the sand of the intermediate bed , which it either 
immediately covers, or abounds in the neighbourhood. When it 
ties upon that sand, where the latter, (as it is in many places, 
especially beyond the Neva,) is perfectly loose and exhibits no signs 
of stratification, it is extremely difficult to distinguish them, except 
where the presence of boulders, or rolled fragments, removes the 
difficulty. I am willing to confess that some parts of the map, as 
I give it, may hereafter be found inaccurate as to the boundaries of 
the intermediate bed on the Carelian side of the country, owing to 
this circumstance : yet where the two sands are perfectly alike in 
colour, and without coherence, when the upper part contains no 
boulders, and the lower no shells, we must have some very infallible 
criterion to be able to distinguish them.. 
