524 
ALL THE DRIFT MUST HAVE BEEN SUBAQUEOUS. 
Nijni Novogorod, the same facts present themselves. To the south of Ustiug the 
granitic and greenstone blocks begin to be scarce, though, as before said, we met 
with a fine example several feet in diameter, even as far south as Garbatof, on the 
Oka. 
The traveller who does not court the long and devious routes by which we 
journeyed, may verify some of the prominent points of observation without quit- 
ting the sides of the splendid chaussee from St. Petersburg to Moscow, which is 
entirely made of northern, granitic and greenstone blocks ; but to obtain a due con- 
ception of the vast area over which the detritus is spread out, as well as to under- 
stand the very irregular dispersion of the blocks,— sometimes placed at wide di- 
stances from each other, at other times in heaps, here quite upon the surface, 
there entangled in mud, — he must traverse not only the northern tracts, but also 
the great central region of Vologda and its contiguous governments. In doing 
this, he may, for a while, be led to speculate upon the former existence of basins 
of sand in one tract and of clay in another ; but the more he extends his survey, 
the more will he find, that all these accumulations and their associated blocks are 
parts of one great system of operations, and that they have all been formed in one 
long period of time. He will also be convinced, that the widely-spread and finely 
laminated sands cannot have been accumulated except under water ; and when he 
sees that these sands and gravel, as on the Vaga, overlie strata replete with pleis- 
tocene or modern marine shells before described (p. 328), he will conclude with us, 
that this great northern drift (by whatever power transported) was deposited on the 
bottom of a sea. This, in our view, is a condition which must be present to the 
mind, before we can draw just conclusions respecting the method by which the blocks 
were transported. As the Valdai Hills, the highest grounds in European Russia 
(from 800 to 1100 feet above the sea), are covered with them, there is no doubt in 
our minds, that the w T hole of that portion of the continent was beneath the waters, 
at the period of the distribution of the blocks. Even in such tracts, however, 
there are phenomena which lead us to infer, that the pi’esent form of the land 
prevailed to a considerable extent even when submerged, and that such outline 
had a great influence upon the manner in which the blocks were lodged. 
By reference to the Map, it will be seen that the southern limit of these erratics 
is by no means uniform, as represented by previous writers, but on the contrary 
very devious. The detritus does not, in fact, occupy an equably shelving, southern 
talus, but, though often on plateaux, it has in many instances followed, even to 
