2 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juue 3, 



was established, no apology is required for the present attempt to 

 group correctly all the ancient sedimentary deposits in those tracts, 

 and to show what additions have been made to our knowledge of 

 them by recent researches*. 



In a memoir communicated to this Society in the year 184'4, and 

 in the first chapter of the work on Russia, I endeavoured, partly by 

 personal exploration, and partly by the inspection of fossils in the Mu- 

 seums of Stockholm and Christiania, to group the palaeozoic masses 

 with Lower and Upper Silurian strata. But as an additional survey 

 could not fail materially to improve my acquaintance with these 

 deposits (particularly as I was on the last occasion accompanied by 

 my able associate, M. de Verneuil), I now place the main results of 

 our last tour before British geologists. These results coincide with 

 the general view of the Scandinavian succession which was before 

 propounded, and which is clearly developed near Christiania in Nor- 

 way. But I have still to describe peculiar features which exhibit, 

 on the one hand, the rupture and isolation of the strata in Dale- 

 carlia and Scania, and on the other, the unbroken and symmetrical 

 succession of the whole Silurian system which Scandinavia affords, 

 and which is exhibited in sections proceeding from Smoland on the 

 main land of Sweden, through the great islands of Oland and Goth- 

 land. 



The sedimentary strata to be described occupy three tracts topo- 

 graphically distinct and distant from each other : — 1. Dalecarlia and 

 the adjacent districts in the north ; 2. a part of Smoland and the 

 adjacent islands of Oland and Gothland ; and 3. Scania, the southern- 

 most part of Sweden. 



In all these tracts Silurian rocks abound, and in the northernmost 

 of them (as in Norway) there are also vast thicknesses of Old red 

 sandstone. These deposits (like others which I have previously de- 

 scribed in Norway and the western and central parts of Sweden f) 

 are separated from each other by great regions of crystalline rocks, 

 the chief masses of which, as before demonstrated, are of azoic 

 characters and of age anterior to the lowest fossiliferous strata. 



Not pretending to be able to describe in detail, the various cha- 

 racters of the crystalline rocks in the vast intermediate spaces, I 

 have not attempted to give a coloured map of the districts under 



* Professor Eichwald of St. Petersburg visited Gothland about three years 

 ago, but although he has alluded to its organic remains, he has given no sections 

 of the island. In the last summer, and two months before M. de Verneuil and 

 myself went thither, the island was examined in some detail by Col. Helmersen, 

 whose account of it has been communicated to the Imperial Academy of Sciences 

 of St. Petersburg. Whilst this author, the chief fossils of whose collection we 

 examined at St. Petersburg, entertains ideas respmbling those we have adopted, 

 in believing the beds to be on the whole equivalents of the Upper Silurian, there 

 is a point of some importance as to the details of succession which will be dis- 

 cussed in the sequel, on which I differ from my distinguished friend and fellow 

 Academician. 



t See Quart. Geol. Journ., vol. i. p. 468, and Russia in Europe, vol. i. p. 15. 



