1823.] Transition Formation of Sweden, 19 



shores. The regularity of the beds, together with the small angle 

 of inclination in general, occasioned the slaty and calcareous 

 rocks of this formation, which contain frequently a great number 

 of fossils, to be considered as belonging altogether to the secon- 

 dary rocks ; while the crystalline sandstones or quartz rocks, the 

 porphyries, the syenites, and granites, are, without hesitation, 

 placed among those of the primitive class. The fossils, how- 

 ever, show sufficiently that these rocks have been formed early 

 after the existence of organic life on the earth. *' They are," 

 says Dr. Wahlenberg, " mostly entomostracites (entomolithes 

 Lin.) and orthoceratites, which both, more than any other petri- 

 faction, differ from animals now existing, and prove their great 

 age. Both are of considerable size, and thin, which evidently 

 proves the perfect quietness of the medium in which they lived. 

 Very remarkable are, in this respect, the entomostracites, fre* 

 quently a foot or more long, and the cylindrical orthoceratites, 

 amounting to two yards in length, which latter lie perfectly 

 entire in the limestone. If we consider further, that a great 

 number of the entomostracites had eyes, and that both they 

 and the orthoceratites exist in very great number, we must 

 be surprised at the powerful organisation with which nature 

 began at once in the north." The ridges of primitive moun- 

 tains, which spread out from the main ridge, separate of 

 course all the different parts where the transition formation is 

 found, and gives them the character so peculiar to Scandinavia, 

 which is, that the transition formation forms a number of 

 different systems, originally limited on all sides by primitive 

 mountains, having, therefore, no immediate connexion with each 

 other, and generally containing the same kinds of rocks, 

 though often in a different order of superposition. One great 

 exception of this law exists, however, in respect to three 

 chains of mountains, that seem to spread from one point, and 

 thus to be connected with each other. This point seems to lie 

 in the main ridge itself. Helagsfjaellet, Svukkujaellet, are 

 mountains composed of sandstone, situated in this main ridge 

 to the east of Roraas, in Norway. From these one branch 

 passes to the south of Norway ; the great lake Mjoesen, which 

 terminates on the west side of the Firth of Christiania, is 

 partly bordered by transition rocks of this system. Another 

 branch passes into Jemteland in Sweden ; it seems to termi- 

 nate at the Storrjoe (large lake) in this province. A third 

 branch passes into the province of Dalerne, and terminates at 

 the lake Siljan. It is extremely remarkable that all these 

 branches have their beds of fossils only at that end which is 

 furthest from the main ridge, when they reach the neighbour- 

 hood of the large lakes ; and it is evident that the closest con- 

 nexion exists between the fossils of the transition formation and 

 these lakes. 



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