356 Br. Hume — Notes on Russian Geology — The Black Earth. 



(Geological Outlines of the Tchernigov Grovernment, p. 129) 

 remarks : " Of special interest is undoubtedly the Loess, which 

 contains a marked percentage of humus, and which may be described 

 as humus-hearing Loess. This structure is always met with in the 

 loiver horizons of the Loess, and may sometimes attain a thickness 

 of seven feet. It is distinguished from ordinary Loess by its grey- 

 brown, chestnut-brown, or dirty grey colour, and is at the same 

 time more compact and clayey ; otherwise its characters are those 

 of the true Loess. Two analyses gave 2'04 and 3-03 per cent, of 

 humus respectively." 



This interesting condition is one to which attention should very 

 specially be directed, seeing that it alone can furnish evidence as to 

 the actual condition of the open country lying to the south of the 

 glacier. There is not at pi-esent sufficient evidence to show that 

 steppe lands, as such, were then already marked geographical features ; 

 and there are some conditions, such as the existence of isolated tree- 

 islands in the midst of the plains, which rather tend to prove the 

 greater extension of woods at that time, and their partial destruction 

 by the flooded Loess-bearing waters. With this brief statement I 

 must leave this complex subject. 



In this paper I have endeavoured to show, first, that the three 

 main propositions submitted by me in my previous note on the Loess 

 are fully confirmed, not merely by the change in character of the 

 strata in a vertical direction, but also by the variations they display 

 when traced horizontally from north to south. 



Not only do we find a gradual transition from beds containing 

 fresh-water shells to those which bear only evidence of a steppe 

 fauna and flora, but we have similarly the existence of marshes and 

 lakes (though disappearing) in the north of Little Eussia ; whilst in 

 the southern parts broad steppe and grassy plains alone prevail. 



These views are further strengthened by a consideration of the 

 faunal changes which have taken place in South Eussia. Here the 

 Mammoth and Ehinoceros seem more abundant in the lower beds, 

 and appear to be more rapidly replaced by the smaller steppe 

 forms than is the case in Germany. Perhaps it may be that in the 

 latter country less continental conditions may have prevailed, and 

 possibly it may never have attained to the perfection of steppe con- 

 ditions developed further east. 



As regards the flora, there remain here and there some traces of 

 the older vegetation, but in general the glacial and Caucasian types 

 have practically disappeared, marshy forms now predominating in 

 the northern, and steppe-forms in the southern governments of Little 

 Eussia. 



The suggestion, then, is, that the position of the Loess has been 

 originally determined by the manner and conditions of its origin, 

 but from the time that the glacial melting ceased to have effect it 

 was subject to the action of denuding influence, the wind becoming 

 a principal factor when the main outlines of steppe-life were 

 established. 



Secondly, the Black Earth is merely a special closing feature in 



