2 3 o POPULAR SCIENCE MONTHLY. 



complete references or bibliographies of the previous work done in 

 the regions described. 



All that can be attempted in a brief outline like the present is 

 to indicate the general scope of the principal papers, and to refer 

 to certain points presenting special interest. 



Following the general course of the first excursion, which is all 

 that can be done in the present article, we have three papers on the 

 geology of the route through central and eastern Russia to the Ural 

 Mountains. Much of this great region has been little studied since 

 the classic researches of Murchison, save that in recent years several 

 Russian geologists have been engaged upon it at various points; but 

 their work is largely inaccessible, and much of it is not yet published. 

 Article No. 1, on the environs of Moscow, and No. 2, from Moscow 

 to the city of Oufa, are by Prof. S. Nikitin; No. 3, by Professor 

 Tschernitschew, covers the route from Oufa to the eastern slope of 

 the Urals. 



In the whole vicinity of Moscow the general section gives, be- 

 neath the modern surface deposits, two well-marked Quaternary 

 divisions, resting upon Cretaceous beds (Neocomian and Aptian), 

 and these upon an important body of what Nikitin has termed Yol- 

 gian deposits, upper and lower. Beneath these are Jurassic beds 

 (Kimmeridgian to Callovian inclusive), underlaid by Carboniferous 

 strata of the stage called here Moscovian. The Quaternary deposits 

 consist of a widespread morainic bowlder clay, unstratified, and 

 filled with transported stones from Finland and northern Russia; 

 westward this passes directly into the lower " Geschiebelehm," or 

 Saxonian bowlder clay, of the Germans, and is the product of the 

 great Russo-Scandinavian ice sheet. Above this is an unstratified 

 bowlder sand, and below it lies a stratified bowlder sand, the latter 

 containing a larger proportion of material from the rocks of the 

 vicinity. Professor Nikitin holds strongly that here, and through 

 the whole of central Russia, there was but one period of ice-covering 

 and moraine deposit, with no indications of repeated advances or of 

 interglacial beds. The upper bowlder sands he refers to the period 

 of retreat of the great Russo-Scandinavian glacier, and attributes 

 them to the action of streams and melting ice. 



The chief point of novelty and interest, however, in this Moscow 

 section is the relation of the upper and lower Yolgian beds, which 

 are important formations over a very large area. They have been 

 variously considered by different explorers of late, some regarding 

 them as lower Cretaceous, and others as upper Jurassic. Their 

 stratigraphic position is clear; their fauna shows marked Jurassic 

 relations at the base and Neocomian relations in the upper portions. 

 Professor Mkitin regards them as a distinct series, lying between the 



