306 Dr. W. F. Hume — Notes on Russian Geology — 



8. The diluvial deposits of the government of Poltava are divisible 

 into three horizons : (1) A fresh- water marl at tbe base; (2) Eed clay; 

 (3) Loess ; all these, however, passing gradually into one another, 

 vphether in respect of organic remains, stratigraphical position, or 

 lithological character. There is no evidence especially favourable to 

 the conception of more than one Glacial epoch. 



9. Seeing then that the typical Loess is, in the government of 

 Poltava, restricted to the region of inferior morainic deposits, and 

 only extends beyond them to a slight extent ; viewing the fact that 

 it is completely analogous to glacial mud occurring in purely 

 moi'ainic deposits, erratic blocks also being sometimes found at 

 its base ; bearing in mind also that Loess may be found below 

 the brown morainic clays — the Loess must he considered as a glacial 

 mud deposited from glacial icaters. 



This valuable contribution to the discussion of the origin of Loess 

 comes from the pen of a distinguished geologist, who possesses a 

 wide knowledge of tbe superficial deposits of Central Eussia and 

 the Poltava government. Tt seems to be the case that the theory 

 adopted by an observer depends very much on the district in which 

 he first studies its characters. Those who examine it along the 

 boundary of the old Russo-Scandinavian glacier, a boundary 

 indicated by morainic claj's containing rocks of Finnish origin, are 

 at once led to regard the Loess as a product of glacial activities. 

 It immediately overlies the Boulder-clay, is stratified at the base, 

 and clings closely to the ancient line of ice-action. Others, travelling 

 over the southern steppe-land, would be struck by the tremendous 

 activity of the varying wind-currents, giving rise to innumerable 

 dust-clouds, and would not fail (now that Baron von Eichthofen has 

 called attention to the importance of these phenomena) to regard 

 these remarkable deposits as resulting from geolian action, a con- 

 clusion which would be greatly strengthened by the discovery of 

 perfect terrestrial mollusca, and the presence of a true steppe fauna. 



As to the glacial origin of some types of Loess, most students of 

 the subject are now in agreement, and it has, as above stated, been 

 conceded by Baron von Eichthofen himself, that such may be the 

 case. 



But it is by no means restricted to the boundary of the glaciated 

 area. It extends all along the right bank of the Dnieper, and is 

 said to be very marked on the banks of the Don. It appears, 

 therefore, that when the general drainage directions of the country 

 were first marked out, the flooded waters carried the fine glacial 

 silt with them, and it was only on the establishment of conditions 

 similar to those now prevailing that the rivers, confined to narrower 

 channels, were engaged in denuding the deposit which their ancestral 

 streams had assisted to transport. 



Whilst on many points we are in full agreement, Professor 

 Dokoutchaieflf scarcely does justice to the vast importance of eeolian 

 activities operating during the many years that have elapsed since 

 steppe-conditions came into existence. 



After a reconsideration of the literature of the subject, I find no 



