QUATERISTARY DEPOSITS OF BRITISH ISLES BROOKS. 299 



1. Pi'esent deposits and old alluvium. 



2. Upper moraine. 



3. a. Land and fresli-water sand deposits, b. Sands with plant remains, 



4. a. Sand deposits with TeUina hnlthica, etc. b. Gray clay with Tellina 



calcarea. c. Clayey sandy sediment with Cardium ciliatum. 



5. Loam with Yoldia hyperborea. 



6. a. Gray fuller's earth with Yoldia nrctiea. b. Dark gray loam with 



Pecten islandicus, Astarte, Leda, Balarms. 



7. Dark sandy clay with Cardiiuii cdiile, Mytilus edulis, Mya, etc. 



8. Lower red moraine. 



From this tlie author makes the following generalizations: 



1. In the region investigated two moraines are usually found, indicating 

 two diii'erent glaciations. 



2. The interglacial marine deposit is formed by two transgressions of salt 

 basins — the oceanic transgression, which indicates an important subsidence 

 of the continent, and that of the White Sea which was marked by the more 

 important second subsidence. The subsidences alternated with corresponding 

 elevations. 



3. The postglacial oscillations of the sea level were considerably more im- 

 portant than the interglacial. 



W. Bamsay (47) maintained that the fauna with Yoldia arcfica 

 was late glacial and not interglacial, but as we have seen in discussing 

 the Skaerumhede series of Denmark, this species also occurs at the 

 conclusion of the penultimate interglacial. The whole series, in fact, 

 bears a considerable resemblance to the Skaerumliede series. If this 

 interpretation is correct no equivalent to the first glaciation of Ger- 

 many has 3^et been found in tlie Dwina region, either because investi- 

 gations have not yet been carried to a sufficient depth or because the 

 region during this glaciation was one of erosion and not of deposi- 

 tion. It is borne out by an observation of J. Geikie's, that between 

 the limits of the old and middle glaciations lakes are few in number, 

 within the limits of the latter they are more frequent, but are most 

 abundant among the terminal moraines of the last glaciation. 



There is one other deposit to which reference must be made — the 

 bowlder-bearing formation of the south part of the Volga Basin, 

 described by A. D. Archangelski (48) and A. P. Pavlov (49), in 

 1910. In the banks of the Volga is found a bed very closelyj 

 resembling a moraine ; elsewhere it is represented by bowlder sands. 

 The bowlder sands lie on the highest part of the watershed ; in their 

 lower part the sands are coarse and contain layers and pockets of 

 bowlders and erratics, among which chert with carboniferous fossils 

 is noteworthy; the upper beds of the sand are finer and contain 

 layers of sandy clay. Among the erratics crystalline stones are almost 

 entirely absent. The cherts attain a diameter of one-half meter. 

 Both authors consider the lower horizon as fluvio-glacial ; the sands 

 are older than the Caspian beds and apparently Pliocene; during 

 their deposition the relief of the ground differed considerably from 



