562 
TCHORNOZEM OR BLACK EARTH OF RUSSIA. 
mud which in Belgium, France and Germany is said to bound the northern drift? 
Though this comparison is made by M. A. Erman, and has been alluded to by 
M.E. de Beaumont 1 , we conceive that it still requires some modification and expla- 
nation. With the ordinary diluvial or drift clay the black earth has, indeed, little in 
common ; for it does not contain a single transported pebble. Besides, it is never 
mixed with that drift which occupies such large tracts of northern Russia. Again, 
the composition of the tchornozem is most distinct from the loss of Germany, 
which light-coloured, sandy, calcareous mass, is abundantly filled with terrestrial and 
lacustrine shells in perfect preservation, clearly indicating that it was accumulated 
on the sides of ancient, wide, lacustrine rivers, which w T ere barred up so as to form 
lakes in the way described by Mr. Lyell, just before the present configuration of the 
land was completed. The fact, also, that the loss has not yet been seen on high 
plateaux, but occupies the sides and bottoms of great valleys, is in itself sufficient 
to prove, that although it may have been accumulated at nearly the same epoch, 
it cannot be considered the exact equivalent of the tchornozem, which, containing 
no terrestrial and fluviatile remains, is found at all levels without any relation to 
the existing form of the land. 
Debarred, by the absence of any portions of plants in its composition, from re- 
ferring it to the decay of vegetation, and unable, from its mineral peculiarity and 
the absence of organic remains, to compare it with any known deposit, let us see 
whether the subaqueous condition of Russia at a comparatively recent period, of 
which we have just spoken, may not help us to solve the problem. 
In no part of the great region occupied by the coarse northern drift is there a 
trace, as before stated, of the tchornozem, though yellow and white sands and 
stiff clays abound, the latter constantly charged with some transported pebbles. 
Extending then as far southwards, as currents or icebergs, to which we have for- 
merly referred, would transport them, it is very natural to suppose that, where 
the northern boulders ceased to advance, the bottom of the then sea, remote from 
any disturbing force, would become covered with fine silt or mud, such as we know, 
from the soundings of hydrographers, is often found beneath mediterranean waters, 
far removed from the action of strong running water. 
If its origin be thus marine, we think it highly probable, that this fine silt may, 
to some extent, have been derived from the destruction of the black Jurassic shale, 
1 See Comptes Rendus, 1841, p. 1223, including observations upon a notice of the tchornozem by our 
friend the Baron A. de Meyendorf. 
