FORMER GLACIATION OF SCANDINAVIA. 365 



period beyond the borders of Scandinavia itself, and especially to ascertain 

 how f;ir the ice sheet which originated on the mountains of that country 

 made its wav in the direction of Russia or Germany, we meet with tlie same 

 difficulties which have already presented themselves in connection with 

 Alpine glacial geology. In Northern Europe, however, we have an addi- 

 tional complication in the undoubted presence of the sea over a portion of 

 the region and during a part of the time. This enables us to appeal to ice- 

 bergs for assistance in conveying the detrital material to a distance from the 

 place of its origin. As it is oidy within a few years that the nature and 

 distribution of the erratics of Russia and North Germany have begun to be 

 studied with care, it need not excite wonder that the facts have not yet 

 been clearly made out. Indeed, a more complicated condition of things than 

 might perhaps have been expected has i-evealed itself, and it seems as if 

 with all the assistance which can be invoked from glaciers, icebergs, and 

 fluviatile currents, there were still phenomena in connection with the distri- 

 bution of the erratics over Western and Northern Europe for which no reason- 

 able explanation could be offered. However much opinion may differ on 

 other points, it will be no longer maintained by any one that the detrital 

 material in question was brought from the north — either wholly, or in large 

 part — by the aid of a Polar ice-cap ; the direction of the strife in North- 

 western Russia and the distribution of the erratics themselves are equally 

 opposed to that hypothesis. 



With regard to the probable extent of the Scandinavian ice sheet and the 

 causes of the distribution of boulders over Russia, the opinions of observers 

 are far from unanimous. The older geologists, almost without exception, 

 favored propulsion of the boulders by great w-aves or powerful ocean currents 

 rather than transportation by ice. Murchison thought that the elevation 

 of the Kola Rouge might have produced a Avave of translation b}^ which 

 boulders would be carried in all directions from the centre of disturbance, 

 and to great distances.* Similar views had been previously maintained by 

 Sefstriim and Bohtlingk.f Nordenskjiild brought in the agency of ground ice 

 carried south from the Polar Ocean by winds and currents. 



Grewingk, who made a carefid o-eoloifical examination of the region bor- 

 dering the Gulf of Finland on the south, also rejects the idea of an ice sheet 



* See Geology of Russia in Europe and the Uial Mountains, Lomlon, 18i5, Vol. I. p. .5.34. 

 t Bulletin Seientifiiiue publie par I'Academie Imperiale des 8016006.=! de St. Petersbourg, Tome VII. lS-10, 

 107-128, and 191-207. Bpricht einer Eeise diiroli Finland mid Lappland. 



