dil2 On the Mica Slate Formation at Flmsberg. 



two extremities of which consist of this same mica slate. In 

 this part of the formation, the mica slate has in every respect 

 the character of a mountain ; a little further to the east it rises 

 into the highest mountains, when its breadth diminishes, and 

 it becomes narrower in proportion as we advance onwards. 



M. Kose follows the rock throughout its whole extent and 

 shews, by noticing all the localities where it is exposed, that 

 the two sides of the gneiss valley do not correspond in their 

 geognostic relations — that the southern limits of the mica 

 slate are moved on the right side much more to the north than 

 on the left side, although the strata on both sides proceed in 

 absolute correspondence with the direction of the course of 

 the river in the valley. These strata have, therefore, been 

 torn asunder, and displaced at the time of the formation of the 

 gneiss valley, and the eastern portion has been moved, but 

 without changing the allure of the strata, along with the gneiss 

 of Geierstein, more to the north than that on the left side. The 

 same appearances, moreover, present themselves in all the 

 valleys transverse to that of gneiss, but not on so large a scale. 



Analysing all the facts, M. Rose remarks, that the strata 

 of mica slate not only appear to have been cut and interrupted 

 In their continuity by the valleys, but that it must have hap- 

 pened that the portions thus separated have been moved in 

 certain directions ; and if we now admit that the valleys 

 among high mountains are nothing else than fissures, and that 

 the strata must have been thus moved out of their position, it 

 is certain that so conclusive a demonstration of this has not 

 hitherto been oifered.* 



The author likewise describes the particular appearances 

 presented by the mica slate in the vicinity of granite, appear- 

 ances which he ascribes to the irruption of the latter, when the 

 slate had already reached its crystalline state. 



In conclusion, M. Rose shews that the mica slate of Flins- 

 berg presents three phenomena deserving of attention ; the 

 direction in which it lies in relation to the summits of the sys- 

 tem of mountains, the manner in which it has been moved 



* Our author has not alluded to the possibility of the portions of mica 

 slate and gneiss being merely great distinct concretions, that is, ahgesonr- 

 derte stUcke, and therefore not moved. — Ed. 



