1846.] MURCHISON ON THE GEOLOGY OF DALECARLIA, ETC. 15 



and loam, this sandstone is nowhere (as far as we could ascertain) 

 exposed as a solid rock in situ ; but being found at intervals, and 

 exclusively along the zone defined, in large untravelled, angular 

 slabs and broken fragments, the rock is extensivel}^ quarried both 

 for millstones and building-stone, and was largely used for the latter 

 purpose in constructing the base of the royal palace at Stockholm. 



Whether this slightly micaceous reddish and pinkish sandstone 

 be referable to the Old red (Devonian) system or to the Lower 

 Silurian, I am not prepared to decide. If time had permitted, the 

 question indeed might possibly have been determined by a visit 

 to the islands off Gefle, where there are limestones with Lower 

 Silurian fossils, and where it is possible that the relation of the 

 sandstone to such fossiliferous strata may be determined. In the 

 meantime, knowing that all this country is very little elevated above 

 the sea, and that ancient gneiss or azoic rock appears in numerous 

 promontories all around, and further, seeing that several varieties of 

 this sandstone had much more the characters of an arkose, or rock 

 regenerated from the gneiss, than any portion of tiie Old red sand- 

 stone properly so called, I am at present rather disposed to believe 

 that it will be found to be of Lower Silurian age. 



Mines, — In taking leave of Dalecarlia and Helsingland, it may be 

 expected that I should allude to the several mining points which we 

 visited, viz. Fahlun, Bisberg and Danemora, and which lie between 

 those northern tracts and the country of Upsala and Stockholm. 



As however the first and last of these mines, the one famous for 

 its copper ores, the other for its magnetic ores, have been described 

 in detail by other authors, I can scarcely pretend to offer much that 

 is new respecting places at which we only remained a very short 

 time. Still I may state that both these mines appeared to me to 

 occur in crystalline rocks more ancient than the Silurian system. 



At Fahlun, the gneiss, or rather mica schist, and its associated 

 quartzose and felspathic rocks, are so traversed by veins, the surface 

 is so strewed over with loose blocks (adverted to in my last com- 

 munication), and the mounds of refuse materials are so large, that, 

 independent of mining statistics and details, and the occurrence of 

 some beautiful minerals, there is little to interest the geologist. 



At Danemora (though surrounded by ancient granitic gneiss) the 

 prevailing rock in which the magnetic iron occurs is a quartzose 

 felspathic rock, which the Swedes term Helle-flinte. M. Erdmann's 

 analysis has proved that it contains at least 1 per cent, more silica than 

 compact felspar rock, being composed of 70 per cent, of silica, the re- 

 mainder consisting of alumina, with some soda, and about |- per cent, 

 of lime. That author, who is disposed to think that some of the 

 Swedish iron ore lies in beds, admits that it here occurs as a sort of 

 vein of irregular form, but contends that as it occupies troughs, and 

 has always been found to be based on schists, it cannot (like the 

 magnetic iron of the Ural Mountains, described in the work on 

 Russia) be considered as pertaining to the class of eruptive rocks. 



\n these splendid open mines or quarries, which have been worked 

 for 400 years, and into whick the workmen are seen descending in 



