1846.] MURCHISON ON THE GEOLOGY OF DALECARLIA, ETC. 11 



or dome of eruptive rock (which here has a granitic character) (q), 

 and falls over ledges of sandstone («), which although highly altered 

 and quartzose when in contact with the granitic rock, becomes at the 

 distance of a few paces a hard quartzose representative of the light- 

 coloured whetstone, and is overlaid by finely laminated dark gray 

 shale (b)*. The shale, which is considerably expanded in this locality 

 and is present in highly inclined strata, contains nodules of argil- 

 laceous limestone, and resembles the strata which overlie the Lower 

 Silurian sandstone along the Omberg on the Wettern Lake, formerly 

 described by mef. It may be fairly inferred that these rocks con- 

 stitute the base of the Lower Silurian group in this tract, because 

 the strata plunging to the south and east are followed in these direc- 

 tions by a considerable breadth of Orthoceratite limestone, which is 

 confluent with the strata before alluded to in the environs of Ratt- 

 vik, beneath which lie the shale and sandstone, as seen in the bed 

 of the Dragsjon. 



On reviewing, then, all the natural evidences which can be col- 

 lected from this confused and broken district, the geologist who 

 has made himself familiar with the mineral characters, fossils, and 

 order of the strata in other parts of Sweden, necessarily concludes 

 that all the fossiliferous beds which are visible in detached and 

 insulated localities around the dome of erupted rocks above men- 

 tioned, or which come out from beneath much crystalline and trans- 

 ported detritus in this part of Dalecarlia, belong to the Lower Silu- 

 rian group, and are referable in ascending order to the sandstone, 

 bituminous schist, Orthoceratite limestone and Graptolite schist of 

 other parts of the country ; the only exceptions being certain sand- 

 stones and flagstones, which from evidence, to be given in the sequel, 

 are supposed to belong to the Old red sandstone. 



Tract of Porphyry and Old Red Sandstone in Elf Dal 

 and on the lahe Wenjan, 



If doubts might exist in the tract above described whether the 

 conglomerates, quartzose bands and flagstones which there occur at 

 intervals, may represent the Old red formation, there can be little 

 hesitation in considering the sandstone of the Lake Wenjan, which 

 is intercalated in the adjacent porphyritic country on the west, to be 

 of that age. 



But even there misgivings might be entertained (so hidden are 

 the relations), if it were not, that in the adjacent tracts of Norway 

 rocks of precisely the same character overlie true Upper Silurian 

 rocks. Now, throughout Dalecarlia, as in other parts of the main- 



* The chief stream at this spot, which issues from the crystalline plateau, is 

 precipitated over a hard siliceo-felspathic rock, of which I did not bring away 

 specimens, and concerning which I have no notes, but my impression is that the 

 mass is an altered sandstone. Rushing through rents in the rock the water cas- 

 cades into a deep abyss, excavated in black schist with calcareous nodules. We 

 detected no fossils in our visit to this picturesque scene. 



t Quarterly Geological Journal, vol. i. p. 477 ; see also ' Russia,' &c., vol. i. p. 17. 



