DRIFT AND ERRATICS SOUTH OF LAKE ONEGA. 
515 
to eight or ten feet below the liquid surface, whilst on tracing them up on the rock 
exposed to the atmosphere we found them persistent to near the summit ol the 
little hill, particularly wherever the thin coating of turf and soil, on which a lew 
stunted fir-trees grew, was uncovered. To the south side of the hill, on the con- 
trary, no such traces of wearing, friction or striation could be seen, and thus we had 
before us, on the edges of Russian Lapland, the very plisenomenon so extensively 
observed by Sefstrom over Sweden, and on the consideration of which we shall 
subsequently dwell, viz. a rounded, worn and striated surface of the northern sides 
of promontories, whose southern faces are natural and unaffected by any mechanical 
agency. 
Whilst great heaps or ridges of rounded granite blocks and gravel occupy the 
tract before alluded to south of Petrozavodsk (masses of the same being doubtless 
buried in the lake), large and subangular blocks have travelled further to the 
south, as we proved by detecting several of them on the very summits of the 
greenstone and syenitic promontories, which in heights of 400 to GOO feet above 
the lake, constitute its south-western coast, and extend to the north bank of the 
river Svir. 
Arrived at the southernmost of these hard promontories, just where the igneous 
rocks subside towards a vast plain, and are no longer to be found across the whole 
regions of Russia,— on a slope, where emerging from umbrageous thickets, we 
enjoyed a magnificent prospect, having the Lake Onega on the left, the deep and 
pellucid river Svir in front, and the undulating regions of Muscovy beyond it, a very 
remarkable trainee of blocks of granite, gneiss, greenstone, &c., mingled with a 
few quartzose boulders derived from the region over which we had travelled, was 
spread out at our feet. This fact is in perfect accordance with that observed on 
the southern side of the plateau of Czarskoe-Celo, and also with the common 
Swedish phenomena ot which we shall hereafter tieat. 
This trainee, of vast width, extends for some versts to the south of the river 
Svir where its numerous boulders, many of them much rounded, constitute a 
water-worn, pebbly surface, not unlike that of the “ crau ” in the south of France. 
After passing over the indurated and quartzose rocks which exist m it, this drift 
also overlaps the same formation, where it becomes the unaltered Old Red Sand- 
stone (Devonian), and in which, on the banks of the Mgra in this neighbourhood, 
we found characteristic ichthyolites (see p. 47). 
The south end of the Lake Onega, equally flat with that of Lake Ladoga, 
