390 
The Hon. Mr. Strangways on the 
clay, which may be traced without difficulty round three sides of it, 
viz. at jD, and 0, (plate 25, fig. 3) and towards Tzarskoe Celo ; for 
it is not one of the least remarkable facts, and one that contributes 
much to the apparent confusion of this tract on a first examination* 
that of the three parallel streams and valleys which intersect this 
eastern ridge between the hill of Pulcova and Tzarskoe Celo (plate 
25, fig. 2) ; the Pulcovca contains the three strata in great strength ; 
the Cuzminca (the middle one) exhibits nothing but the blue clay ; 
and the channel which conducts the waters from the gardens of 
Alexandrofsky towards the plain, near the village of Cuzmina, is 
cut in beds of limestone the most regularly horizontal in which it 
ever appears, (pi. 24, fig. 1. and pi. 25. fig. 1.) On the other side, 
the limestone may perhaps extend as far as the hill of Pulcova, the 
top of which, however, is a large deposit of diluvian gravel ; but 
there is no reason to imagine it goes any farther ; and the hill of 
Penty, the only one on this ridge which approaches that of Pulcova 
in height, shews no signs of it (pi. 27, fig. 1 ). 
The landslip, at /, is a mere recent accident, occasioned by springs 
which issue in abundance from the sides of these valleys, and which, 
when the bogs on the table land are overcharged by the melting of 
the winter snows, are quite sufficient to produce such effects, and 
augment the streams to such a degree as to keep constantly under- 
mining large cliffs, which in summer overhang inconsiderable 
brooks, or chains of stagnant pools ; to this must be added the 
expansion produced by the alternate thaw and frost, which, on the 
face of cliffs and rocks where the snow does not lie, penetrates to a 
great depth. Even in summer, after sudden rains, these rivulets, 
flowing in deep ravines, and among and over vast boulders of granite, 
acquire the character of mountain torrents ,(P1, 26, fig. 1). 
