252 IReport on the Geological Observations made in 1838-39. 



but at Soderliamm, fifty leagues to the north of Stockholm, he observed, 

 at a height of about 42G feet above the Baltic, and on the surface of a 

 small mountain which appeared to him to have evidently been washed 

 by the sea, a detritus of shells of the genus Mytilus, among which he 

 recognised the valves of Tellina Baltica, a mollusc very common in 

 the present waters of the gulf. This observation agreeing with data of 

 the same kind collected during the expedition, especially observations 

 made in the Gulf of Christlania, has aflbrdcd a subject for a disserta- 

 tion found among M. Robert's manuscript memoirs. The author hav- 

 ing observed the strice or scratches, furrows, or grooves, which many 

 geologists, especially M. Sefstrom, and long before him MM. Las- 

 teyrie and Alexander Brongniart, have noticed on the surface of the 

 rocks of Scandinavia near collections of erratic blocks, and which these 

 observers have considered as unquestionable marks of the violent trans- 

 portation of these blocks in a direction from north to south. M. Robert, 

 we say, has remarked, 1st, that the grooves in question follow the direction 

 of the strata, and this direction is almost invariable;} 2d, that there is a re- 

 lation between these grooves and the facility which certain lamina possess 

 spontaneously to undergo alteration more than the neighbouring .lamina, 

 and that the coincidence is purely fortuitous between the direction of the 

 inclined beds which compose the ground, and the elongated form of the 

 collection of erratic blocks. In a word, M. Robert is of opinion that these 

 blocks are the result, not of a great diluvlan cataclysm, but of an action 

 alternately backwards and forwards, produced by the currents and waves 

 of a sea which covered, at a very remote period, all the low lying portions 

 of the Scandinavian countries. He likewise thinks that the blocks of 

 large dimensions must then have been transported on floating masses of 

 ice annually detached from the continents, as he saw take place at Spltz- 

 bergen. Finally, he considers that the kind of belt of marine alluvium 

 which appears on so many elevated parts of the coasts of Norway, Lap- 

 land, and Sweden, as the last limits of the effects of the sea, before the 

 slow, emerging, and successive elevation of this part of Europe, had pro- 

 duced an apparent sinking of the level of the ocean. 



The reporter has not thought it necessary to enter into the discussion 

 of these explanations ; he has satisfied himself with stating them. 



Passing on to M. Robert's observations In reference to Russia, M. Cor- 

 dler announces, that the collection illustrative of these observations con- 

 tains a great number of varieties of rocks which were unknown to us, 

 and the existence of which might have appeared questionable, if they had 

 not been actually produced for examination ; such are the old splrlferous 

 or productus limestones, white, tender, and friable, like common chalk, 

 or rather arenaceous, and resembling the coarse limestone of the neigh- 

 bourhood of Paris ; such, too, are the vesicular quartzes, analogous to our 

 mill-stones, but which nevertheless belong to the old limestone-system ; 

 Such, finally, are the magnesian limestones dependent on the same sys- 

 tem, and which are cavernous and friable, like the dolomites of the party- 



