W. F. Hume — Notes on Russian Geology. 557 



appears to have been covered by the sea, the shore line being found 

 in the N. of the Tchernigov Government, as evidenced by the broken 

 fragments of Beleranites and Phosphoritic nodules which occur at 

 the base of the Lower Tertiaries. To this period belong the 

 Spondylian Blue Clays of Kieff, similar beds having also been proved, 

 to exist in the other governments mentioned at the beginning of this 

 article. 



In the Crimea, too, the ubiquitous Nummulites appear to have 

 found a congenial home. 



The Northern Continent seems to have slowly advanced south- 

 ward, for the clays are overlaid by an important sei'ies of glauconitio 

 sands, containing amber and plant remains. This succession is 

 well-marked in the Kieff, Kharkoff, and Poltava Governments. 

 Indeed, in Miocene and Pliocene times S. Eussia becomes sharply 

 divided into two areas : the Northern half, in which a thickness of 

 unfossiliferous sands (ferruginous or beautifully fine and white), 

 succeed the amber-bearing beds, and separate them from the 

 variegated and freshwater clays which preceded the glacial clays 

 and the Loess ; and a Southern half, in which a marine fauna still 

 flourished, although even here, too, the sea was gradually driven 

 back till the present outlines were more or less clearly defined. 



Indeed, the facts seem to point to a gradual southward advance of 

 the land area, or, as Professor Suess would have it, retreat of the 

 sea ; an advance checked it may be for a time by the presence of an 

 ice-sheet, and the consequent changes involved thereby. 



As Professor Suess has pointed out, there appears to be a very 

 intimate relation between the Loess and the Glacial Drift. In 

 N. Eussia there is nothing but Glacial Drift at the surface, while in 

 the South the Loess entirely takes its place, but between them is a 

 band, passing into Galicia and Saxony, a band along which the Loess 

 overlies the Glacial Drift, and it is just along this line that the basal 

 stratification is most clearly marked. This relationship appears too 

 striking to be casual, and I am inclined strongly to regard the original 

 constituents of the Loess as being the finely-ground materials due to 

 the combined action of the ice-sheet and the increased drainage 

 activities resulting therefrom. This appeared to be the answer to 

 the question which thus presented itself. Here is a vast deposit in 

 which evidently denudation is now exceeding deposition. Can the 

 original materials of such a deposit have been originally derived 

 from actions which are still proceeding in the same area, or must 

 some other explanation be sought for their origin ? 



Though the above cause may give a clue to the origin of the 

 materials, other actions may by no means be left out of account. 

 There, are for instance, speculations which may become important 

 if based on sufficient proof. Thus, is the earth soflSciently plastic 

 to be compressed by a mass of ice resting for lengthened periods on 

 the same tract, and if so, would the depression have a corresponding 

 elevation at some distance away ? Even a small elevation in the 

 S. of the Eussian Empire would be sufficient to convert the central 

 tracts into au " abflussloses Becken ; " but I know of no evidence 



