568 
ELEVATED RIDGES OF BLOCKS ON BANKS OF LAKES. 
73. 
Hill of KameuiUor. 
Lake Onega. Siliceous Sandstone. 
is about twelve or fifteen feet wide in its central part, from which its surface gra- 
dually slopes away on each side, so as to leave a width of about thirty paces for its 
base. It is composed of angular blocks (some not less than ten and twelve feet in 
their greatest diameter) which consist exclusively of the same quartzose sandstone 
as that which constitutes the subsoil on which they lie. The sloping surface of the 
Kamenibor, still higher above the ledge, presents, it is true, some scattered granitic 
boulders (/), but we could not detect one of them in this ridge of angular blocks of 
siliceous grit. To consider it as an ancient edge of the lake which had been drained 
off to its present level, appeared, at first sight, to be impossible ; for the gigantic, 
angular and unworn blocks, only slightly covered by lichens, and piled up like the 
broken rocks in a foreground of Salvator Rosa, were totally unlike any ancient lake- 
banks we had ever seen. They were, indeed, wholly dissimilar to the parallel roads of 
shingle at GlenRoy in Scotland, which several geologists have attributed to lacustrine 
deposit 1 . We therefore began to speculate on the possibility of these coarse angular 
masses, in situ, being the results of ancient rents caused by earthquakes, which 
fissuring the strata in lines 'parallel to the lakes, had left these shattered piles in their 
present linear form. This hypothesis seemed, however, to be untenable, both from 
the very condition of the blocks, and still more by our observing two lower terraces 
(b b ) formed of similar materials, and lying at other levels between the higher ledge 
and the shore of the lake. We then began to think, that although unlike anything 
1 No subject has afforded a more fertile theme for discussion than the shingle terraces or parallel roads 
of Glen Roy. Dr. Macculloch, Sir G. Mackenzie, Sir J. Dick Lauder, and Mr. C. Darwin, have written 
largely upon them, the first three referring them (under different modifications) to lacustrine deposit, the 
latter to submarine influence, when these tracts were fiords or ancient estuaries. In this last opinion 
we entirely concur, as might be inferred from what we have said in the previous chapter on Scottish drift and 
gravel. It ought further to be stated, that when Professor Agassiz visited Glen Roy (anno 1840), he 
considered the parallel roads to have been formed by ancient glacial action, suggesting that a lofty wall 
or mountain of ice had barred up former lakes, which were drained off by its disruptions. Without now 
entering into these theories, we have only to say, that our cases of Petrozavodsk and the Dwina are very 
different, indeed, from the phenomena of Glen Roy. 
