A. N. KKASSXOF- 



-THE RUSSIAN "BLACK EARTH." 



73 



and marshy land to the stage of the steppe), the relations existing between relief 

 and soil and the vegetation of the prairies described by Engelmann, Whitney and 

 Winchell (who draw a picture, exceedingly like that seen in Russia, of regions with 

 loessoid soil, covered by prairie, with elevated spots, stony and drained and covered 

 by forest, whose domain becomes larger despite human culture 1 , the influence of 

 the climate analogous to the climate of the Russian steppes, the value of which bad 

 been formulated by Professor Dana —all this reminded me very forcibly of what I 

 had seen in my country. Moreover, the whole history of the continent, from the 

 Paleozoic downward, permits the drawing of analogies between the great valley of 

 the Mississippi on the one hand and the Euxine-Caspian-Siberian valley on the 

 other — these youngest parts of the two continents situated between the Paleozoic 

 regions and the mountains of more recent origin ; both were reservoirs of the 

 glaciers of the glacial epoch, and both had their epoch of .inundation. 



In closing this essay I take the liberty of making a special appeal to those 

 American geologists who are interested in the Quaternary geology of their country 

 If it is possible to establish closer relations between Russia and America, the ques- 

 tion of the origin of the American prairies and of the Russian steppes will be 

 easier to solve. If it is possible on the one hand to find in America relations be- 

 tween soil, climate, relief, and vegetation analogous to those of Russia, as well as a 

 dependence on climate analogous to ours ; if the distribution of the ''black earth ' 

 around the valley of the Mississippi shows the same peculiarities as that around 

 the Euxine-Caspian depression ; finally, if the hypothesis of Professor Lesquereux 

 is confirmed by more numerous proofs in Russia and in America, I hope the ques- 

 tion of the age of the "black earth" will be solved, and it may be decided more 

 positively whether most of the American prairies are merely a less advanced stage 

 of evolution than those of Russia. Allow me, then, to repeat the wish that the 

 geologists of these two countries may work together and in harmony for the solu- 

 tion of this question, the interest and practical value of which are beyond doubt. 



The detailed results of Professor Dokucbayef 's observations on the " black earths " 

 of Russia are summarized in the following table, which is extracted from his work 

 on the Russian chernozem, pp. 353-372: 



Thickness and Contents in Humus and hygroscopic Water of the different Soils of Russia. 



Left Shores of the Volga and the Kama. 



X— Bum,, •■oil. Soc. \u., Vol. 3, 1891. 



