W. F. Hume — Notes on Russian Geology, 553 



passes into a layer of true Black Eartli. The whole is only about 

 three feet in thickness. 



The above must not be confounded with a similar occurrence 

 which differs only in the fact that the humus occurs near the base, 

 instead of at the u^jper part of the Loess. This character is very 

 frequent, and may perhaps have a special significance, but I have 

 been unable to obtain sufficient evidence bearing on this point. 



The following conclusions may be formulated : — 



1. In general the Eussian Loess contains quartz grains of ap- 

 proximately equal size. 



2. It is usually unstratified, but in certain districts possesses 

 well-marked stratification at the base. 



3. It possesses typical capillary structure. 



4. It has a tendency to split in a vertical direction, giving rise to 

 perpendicular walls. 



5. It is often very rich in carbonate of lime and humus. 

 Finally, in its wider sense it may be distinguished — 



(A) By its irregular vertical and horizontal distribution. 



(B) Its pi'actical independence of the subjacent strata. 



It would be interesting to know how far (B) is an absolute truth. 

 It seemed to me that the calcareous concretions appeared to be more 

 common in the districts adjoining Cretaceous outcrops, that in the 

 Permian districts the Loess was redder in colour, perhaps due to an 

 intermixture of Permian red sands, whilst near the Arch^an gneisses 

 mica and felspars are more common constituents. Such changes 

 rtiight indeed be due to wind action alone, as these small peculiarities 

 are often observable some distance from the rock outcrop, to whose 

 presence they may have been originally due. Positive proof or 

 otherwise could only be given after long and patient research. 



The evidence adduced would be incomplete without some account 

 of the paljeontological contents. Indeed, the results are so similar 

 to those obtained in other parts of Europe, that they lend final con- 

 firmation to the view that the Loess of Russia is more or less coeval 

 with the Loess of Central and Western Europe. 



My own conchological finds were too meagre to enable me to make 

 absolute statements on this subject ; but happily evidence is forth- 

 coming from other sources. 



One of these, Mr. Belt's " Steppes of Southern Russia" (Q.J.G.S., 

 vol. xxxiii. 1877, pp. 843-862), contains several lists of the shells 

 collected by him while on a short journey in S. Russia. Amongst 

 those mentioned the familiar forms of Helix hispida, Succinea ohlovga, 

 and Pupa marginata may be noticed. Another, Prof. Armachevsky's 

 " Geology of the Tchernigov Government," also contains much local 

 information on this point, but being in the Russian language, is not 

 so readily accessible to the general reader. On p. 16 of the latter 

 work a deposit of Loess is mentioned as occurring near the valley of 

 the Desna, in the above government. It contains calcareous con- 

 cretions, and lies unconformably on the Cretaceous. The following 

 shells were met with : Ptipa muscorum, Succinea oblonga, and Helix 

 hispida. After mentioning a large number of similar cases he 



