S68 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 8, 



of a mass of drift and the increased velocity of the current may 

 have acted with much energy on the enclosing 'sides. Without 

 however too much insisting on the value of my own hypothesis, I 

 specially dwell on this feature of the Swedish phsenomenon to prove, 

 that even supposing it were possible that terrestrial glaciers could 

 have advanced over these flat regions, they never could have left 

 such effects behind them ; for it is quite certain, that if by any 

 possible combination such bodies could have moved over so level 

 a region*, they must, according to all the Alpine analogies offered 

 by Professor Agassiz, have left decisive striae all along the sides of 

 the parallel or flanking rocks through which they advanced. A 

 comparison of the diagrams of Professor Agassiz, exhibiting such 

 lateral effects of the walls of glaciers, with our Swedish examples, at 

 once indicates the important distinction ; and in the sequel, other and 

 still more cogent reasons will be given to show the utter impossi- 

 bility of explaining the abrasion and striation of the rocks of Swe- 

 den by glacier action, however much these rocks present surfaces 

 in many respects precisely similar to those produced by glaciers. 



The environs of Upsala abound \>ith long, linear, sandy osar, oc- 

 casionally only containing coarse gravel, and these range from north 

 to south, particularly to the east of the river, whilst to the west of 

 that stream, low long ridges of granitic rock are parallel to them. 

 In other words, the osar appear as undulating deposits of unequal 

 altitude, occasionally rising to 100 or 150 feet above the lower 

 country, and they appear to have here assumed their linear direction 

 in consequence of the rocky elevations on their flanks. In these 

 osar we have the clearest proofs that the large angular erratics are 

 always at the surfacef. On the same line of os is the hillock im- 

 mediately to the S.W. of Gamla Upsala (Old Upsala), to which I 

 have particularly directed attention in my work on Russia, as exhi- 

 biting not only many angular blocks both near its summit and on its 

 southern face, but also peculiar small terraces on its northern face 

 and slope, which seemed to me to render it more probable that 

 such great angular superficial blocks had been quietly transported 

 to their present habitats in icebergs or on rafts of ice than any 

 other example hitherto cited. I here reproduce the diagrams (figs. 

 13, 14). They seem to support the hypothesis I advocate not only by 

 illustrating the comparative absence of blocks on the north side and 

 their increasing abundance from the summit to the south side, but 

 also by accounting for the gravel terraces, since I assume that, after 

 the completion of the osar drift, a large iceberg must have been 

 floated southwards by currents then prevailing, and was arrested on 

 the northern face of the apex of the hill ; that at first there was 

 accumulated around its base the larger and lower terrace (a), and 

 that with the lapse of successive seasons and the perpetual action of 



* The heights of some central grounds in Bleking and Smoland are quite as 

 great as those in the districts further north. 



t One of these, called the Stor-Stens-Kulle, to the north of Upsala, is perched 

 on the very summit of a sandy and gravelly os. 



