18460 



MURCHISON ON THE SCANDINAVIAN DRIFT. 



369 



the current, this was successively reduced so as to account for the 

 gradually smaller and higher terraces b, c, d. I suppose also, that 

 while melting it parted at intervals with some of the blocks which 

 it carried, until, worn away to the minimum size at which it could 

 hold together, the mass was entirely dissolved and its spoils deposited 

 on the summit and southern slope of the hill to which the waters 

 would naturally bear them. 



Fig. 13. 



Fig. 14. 



The environs of Upsala are also of much interest in establishing, 

 beyond the power of contradiction, that the osar subjacent to the 

 angular blocks were really aqueous and marine drifts ; for in the 

 sandy and gravelly beds of the os on which the castle stands, Mr. 

 Marklin found several species of shells, including the Tellina baltica. 

 Other argillaceous beds of blue clay which occupy the banks of the 

 river, on either side of which the osar rise up, are also in some spots 

 absolutely loaded with this shell, showing that the whole base of the 

 soft and overlying formations is truly of aqueous origin of no very 

 distant date, the shells being specifically the same as those now 

 living in the adjacent Baltic, and exhibiting their nacre perfectly 

 preserved *. 



In proceeding to the north of Upsala, whether to Iledemora and 



* Mr. Lyell has already stated this fact respecting the presence of Baltic shells 

 in and below the osar. They occur, in fact, in many parts of Sweden, and thus 

 afford proof, in addition to the fact of the numerous raised sea-heachcs of Uilde- 

 valla, that the sea covered all the low tracts of Sweden at a comparatively mo- 

 dern period. 



