Dr. Hume — Notes on Russian Geology — The Black Earth. 303 



VI. — Notes on Eussian Geology.^ 



By W. F. Hume, D.Sc, A.E.S.M., F.G.S. ; 



Demonstrator in Geology, Eoyal College of Science. 



III. The Black Earth. 



IN a previous paper on the Loess of S. Eussia, I endeavoured to 

 discuss its character and origin, and to compare the facts 

 observed with the results obtained by many students of the latest 

 phases of our earth's history. In so doing I overlooked two articles 

 on this subject, which appeared in the Geological Magazine for 

 1882, and embodied the views held by Baron von Eichthofen and 

 Sir H. Howorth respectively. These may be briefly considered ere 

 we turn to a special examination of the structure and relations of 

 the Black Earth. An examination of Sir H. Howorth's statements 

 reveals serious points of disagreement between the theories pre- 

 viously or subsequently suggested, and those which he himself 

 holds. At the outset (loc. cit. p. 12) Sir Henry remarks : " Loess 

 is not found in S. Eussia, nor yet in the flat country bordering." 

 Such a proposition would be deeply resented by the geologists of 

 that country, and has unconsciously on my part received its answer 

 in my previous paper, where I have shown Loess to be one of the 

 most striking deposits of some of its southern governments, and 

 that it presents all the most important features mentioned as charac- 

 teristic by Baron von Eichthofen. 



But Sir Henry goes further, and having successively attempted to 

 crush the various views held on this subject, propounds a theory of 

 his own, which may be considered in the light of the results obtained 

 from the particular district under discussion. The proposition prac- 

 tically may be stated thus : The Loess is a subterranean or volcanic 

 product, which has been subsequently distributed by diluvial action. 



This suggestion is also extended to the Black Earth, which, it is 

 stated, is distributed about an apparently recently disturbed mountain 

 focus, viz. the Southern Urals. So far is this from being the case 

 that the Kharkov government, where some of the finest Black Earth 

 districts exist, is 1000 miles from the above mountains, and over 

 500 miles from the Carpathian range. In reality the country is 

 practically undisturbed, the Tertiary and Cretaceous beds having so 

 small a dip, that the slight rolling of the strata is only observable when 

 the conditions along a line of over fifty miles are passed in review. 



Further, there are no traces of volcanic action in any of these 

 central districts. The nearest exposures of eruptive rocks are 

 probably the Carboniferous andesites and rhyolites of the south 

 of the Ekaterinoslav government, the diabases (probably very old) 

 in the W. of the same province, and the basalt mass rising through 

 the Chalk of Central Poland. 



Finally, if the Loess were of volcanic origin, it would contain 

 traces of minerals, and possibly of structures produced under such 

 conditions. Such evidence is not only wanting, but is a priori im- 



' For No. I. Cretaceous, see Geol. Mag. September, 1892 ; No. II. the Loess, 

 see Geol. Mag. December, 1892. 



