Scandinavian Diluvlinn. 313 



wrote to M. Dumont d'Urville at the request of M. Sefstroem, 

 and which M. Arago did me the honour to read to the Academy 

 of Sciences, and of which there is an extract in a French jour- 

 nal. On this account, I shall not speak at present of the ideas 

 of M. Sefstroem. 



*' As to the specimen sent herewith, it was destined to accom- 

 pany the letter to M. Dumont d'Urville; but this was impos- 

 sible, as the letter was sent by post. You will remark that it 

 appears as if polished by emery in a constant rectilineal direc- 

 tion. All our mountains have the NE. side worn by parallel 

 furrows, rectilineal in the direction from NE. to SW., wliich 

 on the granite are often much deeper and broader than on this 

 harder stone. The SE. side, on the contrary, still exhibits 

 the angular outline formed at the time of their souUvement. 



" M. Sefstroem explains this phenomenon by a current of 

 water and rolling stones, of which this current has left, at least 

 with us, enormous remains. The memoir of M. Sefstroem, pre- 

 sented to the Academy (of Stockholm) two years ago, is to ap- 

 pear immediately, and will probably be reprinted in Poggen- 

 dorjf^s Annalen, The engravings, rather difficult to execute, 

 which accompany it, have been the cause of the delay in its 

 publication."" 



I have the honour to exhibit, to the Academy the fragment 

 of polished porphyry of Elfdalen, mentioned in I\I. Berzelius^s 

 letter ; and I add to it, as means of comparison, a fragment of 

 Jurassic limestone similarly polished, detached from a polished 

 surface of great extent, which M. Agassiz shewed me last July 

 at Landeron near the Lake of Neufchatel. 



I should think it desirable for the naturalists of the expedi- 

 tion to bring back as large specimens as possible of these po- 

 lished rocks of Sweden; for a much more just idea is to be 

 formed of them from large specimens. As they have a govern- 

 ment vessel at their disposal, they will possess facilities in this 

 respect which will perhaps not be afforded again for long. 



Many geologists have thought that masses of ice acting as 

 rafts, or in some other manner, have performed an important 

 part in the transport of erratic blocks. As the expedition is to 

 visit Spitzbergen, where there are magnificent glaciers, it will 



