1846.] MURCHISON ON THE SCANDINAVIAN DRIFT. 377 



of the region are such, and the details in it are so developed, that 

 by no physical possibility could terrestrial glaciers have traversed 

 these vast low and undulating tracts, still less could such bodies 

 have advanced from the Baltic, up-hill over the Valdai hills and 

 other eminences of Poland and Germany, from whence the rivers 

 descend to the Baltic on the north. We believe that at the period 

 when these currents were set in motion (and this we believe to have 

 been effected by successive and sudden upheavals of the northern 

 chain of Scandinavia, aided perhaps by a corresponding depression to 

 the south, which deepened the sea in that direction, and which also 

 produced great waves of translation), various appearances were pro- 

 duced by friction and by the passage of masses of gravel and sand, 

 which left behind them an impress on the surface of rocks since raised 

 into dry land, very similar to that which has been produced in moun- 

 tainous or alpine countries by land glaciers. We saw no reason at the 

 time, nor do we see any reason now, to doubt that great and heavy 

 masses of drift, when impelled by powerful, active and rapid marine 

 currents, may have produced effects similar to those now and for- 

 merly produced by the slow onward march of a glacier. In addi- 

 tion to our former hypothesis, we now, however, willingly append to 

 it a portion of the theory of M. Durocher, who, not considering the 

 weight of the drift as a necessary postulate, explains the polished 

 and grooved sides and surfaces of narrow canals and longitudinal 

 cavities by the greater velocity and force of the currents wherever 

 they were confined and forced through contracted channels. 



But in excluding, together with Sweden, all the lower tracts of 

 northern Europe, and also of the British Isles, from the possible ap- 

 plication of the glacier theory, we differ somewhat from M. Duro- 

 cher, and are disposed to admit its strict and true application to 

 many isolated tracts, whose lofty mountains and divergent valleys 

 afford, as in Norway, the geographical features required and the 

 postulates of the Alpine problem. The surfaces of these, indeed, 

 offer proofs of the movement of glaciers having formerly acted on 

 their surfaces, and we doubt not that the present glaciers of Nor- 

 way (some of which exhibit proof of having formerly extended 

 to greater distances than at present from their respective common 

 centres) may have been more extensive at a former period, parti- 

 cularly in their range to the N.N.E. We think that parts of them 

 may then have been prolonged into a glacial or icy sea, which 

 when broken up afforded, in the first instance, many of the mate- 

 rials of the drift we have described, and that from their edges may 

 afterwards have been detached numberless icebergs, which floated 

 away many angular blocks to distances of hundreds of miles to the 

 spots where they are now seen piled up, often upon the surface of 

 low eminences. 



The feature however of the immense masses and piles of angular 

 blocks in ridges and m situ, by which the attention of my fellow- 

 traveller and myself was last year most especially arrested, is one for 

 which it is perhaps more difficult to assign a probable cause. 



Any one unacquainted with certain northern operations of frozen 



