510 
NATURE OF THE DRIFT IN THE BALTIC PROVINCES. 
under consideration have been uniformly covered with crystalline materials which 
have proceeded from Scandinavia and Lapland only. 
Confining ourselves, in the first instance, to the Russian detritus, we now pro- 
ceed to give a succinct account of its nature and distribution between the mouth 
of the Niemen on the south-west, and that of the Dwina of Archangel on the north- 
east, — such, in fact, as it appeared to us when we travelled along the southern 
edge of the crystalline rocks, from whence all the debris has been sent forth. By 
this means we shall make a transverse section, as it were, of all the drift on a line 
little distant from the source of its origin, and then follow it to distant parts of the 
interior of Russia. 
Geological travellers who, like ourselves, have crossed over Northern Russia 
from its western frontier on the Niemen to Archangel on the White Sea, cannot 
avoid being struck with the general sameness of this distribution, and also with the 
fact, that the detritus has been borne southwards in long zones, often separated 
from each other by depressions, occasionally of great width, in which few or no 
blocks are discernible. 
Thus the broad depression of the Niemen, and even the low argillaceous hillocks on its eastern slopes, are almost, 
if not entirely, exempt from blocks, the chaussee for the first two Russian stations through the forests being mended 
with small gravel brought from distances of fifteen and twenty versts. In approaching the third station, however, 
blocks appear on the surface of the clay drift. Again, the summits and slopes of hills (200 or 300 feet high) on 
both sides of the station of Bublia, — particularly the plateau to the north-east of it, — are covered with blocks of 
granite, porphyry and other Swedish rocks, both rounded and subangular, and occasionally of large size, together 
with corallines and shells of Silurian rocks, whilst the intervening valley, in which the Wendau Canal has been cut, 
is exclusively occupied by fine yellow sands. Having passed the plateau between Lithuania and Courland, where 
mud and northern blocks still prevail and are widely spread over the latter province (around Mittau), we again 
remarked the comparative absence in the estuary of the Diina, particularly on the low grounds and hillocks forming 
the eastern banks of that river, which are almost exclusively occupied by loose sands, immediately surmounting 
the Devonian strata with their ichthyolites. 
Passing to the east of the station of Walk, no sooner do argillaceous hillocks (about sixty or eighty feet above the 
plain) appear, than again they are covered with erratics of gneiss, granite gneiss and other northern blocks of 
various sizes. The cliffs forming the eastern or right bank of the river Embach are loaded on their surface with 
similar detritus. Thence to Kaigatz the drift is also argillaceous and blocks abound, extending all along the plateaux 
to Dbrpat, where the larger granitic blocks repose on an argillaceous and sandy alluvium, which separates them 
from the subjacent Devonian sands and marls. 
In ascending from Dorpat and the lake Peipus to the calcareous plateau 1 
1 In this plateau, extending by Shavli, &c., some Silurian limestone, which we have described in the 
3rd Chapter, exists in situ, but the greater portion of the calcareous debris we met with had evidently 
been drifted from the north — probably from Oesel; for the corals which are so abundant in the detritus 
do not occur in the cliffs of the mainland, but are Upper Silurian species which abound in situ at that 
island. 
