414 The Hon. Mr. Strangways on the 
its various outliers on each side of the Neva, which are not capped 
by any other antediluvian formation. I shall take the latter first, 
as the former will lead more naturally to the consideration of the 
limestone immediately above it. 
All the chains of hills comprehended within that part of the 
district I am describing, which are situated on the right of the 
Neva, and which have already been mentioned in detail in the 
beginning of this memoir, are composed of the loosest and most 
sandy form of the stratum in question, as well as the plain which 
supports the bogs between the ridges of Toxova, Riabova, Coul- 
toushy, and the lake Ladoga. This will be better understood by 
the section, fig. 4, Plate 29. The sand on the banks of the 
Okhta, especially below Mourina, and that west of Pargola, 
I imagine to be diluvian, for reasons to be stated hereafter. 
Its colour is in general yellow, and it much resembles the sands 
of Prussia and the north of Poland, as well in geological character 
as in the scenery it presents. Nothing can be more desolate than 
the little valley of Diboun, in which a stream of the brownest hue, 
formerly dammed up for the purpose of supplying with water 
an iron work now removed, forces its way with difficulty through a 
bog impassable to human footsteps (as are many others in this 
country) except after 10° Reaum. of frost. In summer, its moist 
and heavy exhalations, exposed for some months to the sun during 
eighteen hours a day, rarely disturbed by a breath of air, and 
confined between tall and gloomy forests of fir and birch springing 
from the arid sand which presents no trace of other vegetation on 
its surface, than grey moss and some species of ferns growing 
among granite boulders, nourish myriads of gnats or musquitoes, 
gadflies, and all the other disagreeable insects which swarm in this 
climate during the warm season. 
