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The Hon. Mr. Strangways on the 
their position. This however may be the effect of cultivation, as 
the soil is extremely shallow, (Plate 29, fig. 3.)* This is very well 
seen immediately below the gardens of a great house, formerly 
belonging to Count Czernicheff, on the Peterhof road, where the 
banks of the stream Coirovca present some excellent sections on 
both sides of the valley in which it flows. They are remarkable, 
not only for these layers of diluvian earth, but also for some of the 
best examples of the veined clay, described in an early part of this 
paper. Between the two formations occurs a bed of pebbles, eight 
or nine inches thick, agglutinated together by a ferruginous sand. 
This bed, though it does not form a hard stone, is yet solid enough 
to project beyond the softer substances, both above and below it, 
and also to fall in large pieces to the foot of the cliff, which may be 
from fifteen to twenty feet high, without breaking. These pebbles 
being primitive, both this pseudo-conglomerate, and the clayey 
layers above it, must be referred to the formations I have called 
diluvian. It can excite no wonder that a diluvian deposit should 
be stratified, although it is but rarely their stratification is distinctly 
perceptible ; a circumstance which is probably owing to the purely 
mechanical nature of the deposit, the comparative rarity of chemical 
combinations on the great scale since the formation of the solid 
strata being notorious to every geologist. To this cause also, as 
well as to their hasty accumulation, may be referred the looseness 
and want of coherence in the diluvian formations. On the Cras- 
ninca, where the layers of clay are grey, or brown and white, and 
the rolled pebbles absent, it seems difficult at first sight to believe 
that it is not some variety of the intermediate bed, in its place above 
the blue clay. They continue every where along this line, 
* See Sketch of the clay veins on the Coirovca. 
