Communications respecting Bocks of Scandinavia. 301 



in exhibiting these fragments to you on my return, and in 

 being able to hear your opinion regarding them. The possi- 

 bility of this mode of their origin was increased In my mind 

 to probability, when subsequently, in the crystalline slate- 

 hills of Dovre-Fjeld and in the Kjolen, I found a similar 

 conglomerate where the inelosures are less affected by the 

 surrounding mass, so that one can more distinctly discern 

 their rounded form. The boulders here also are gneiss of 

 various appearance, and the rocky bed in which they lie is a 

 talcose mica-slate. It is a species of Valorsine conglomerate. 

 Nearer Sneehatten these slates assume the character of horn- 

 blende ; and in the same ratio as they do so the conglome- 

 rates also appear. Indeed, we still see very distinctly, by 

 their angular remains, that they once existed here also ; but 

 the appearance of the hornblende gave tlie signal for their 

 destruction, and thus produced a rock which may be con- 

 sidered as analogous to the diorite of Christiania. If, for 

 instance, a metamorphosis should seize ourNagelfluh, it would 

 first assume the character of the conglomerate of Dovre- 

 Fjeld, viz., rounded boulder stones in a crystalline ground of 

 rock. If the metamorphosis should proceed furtlier, then the 

 limestone and small pebbles, for example, would disappear, 

 and at last there would remain behind only granite and gab- 

 bro-boulders, which offer the greatest resistance ; yet these 

 also would partly dissolve, and thus lose their rounded form. 

 In short, we would have the rock of Christiania. 



The gi'anular limestone of Gjellebak presents the pheno- 

 menon of Monzon ; but here, in Norway, beside tremolite, 

 idocrasc, garnet, and blende, there are very distinct traces of 

 petrifactions, the very same as occur in the transition rocks of 

 this country. Inlike manner, the strata of marl among lime- 

 stone still remain pure ; and this proves, that the metamor- 

 phic process has been easy and gradual, and that it was not 

 a destructive granite, which, by its heat, melted the mountain 

 to a fluid mass, out of which a new rock, the granular lime- 

 stone, was crystallised. The gradual change of form of a 

 body which still continues solid, is a problem at which many 

 are confounded, because they cannot imitate the great expe- 

 riment of nature. On a grand scale, it does not hold ; but 

 in a smaller way, the barley-sugar, which, in course of time, 



