164 Ml* StiiJer on Ihe Geological Structure of {he Alps. 



intermediate valleys between the northen part of the St Go- 

 thard and the upper Engadine. 



The effects of the dislocations produced in these directions 

 and in many others, are limited to the zone of the Alps, and 

 do not even reach their northern and southern limits ; never- 

 theless, the formation of the valleys parallel to the Alps, and 

 even of the Alpine valleys in general, appears to be more re- 

 cent than the formation of the central masses and of the chains 

 having inclined beds, for they cut obliquely the axis of these 

 soulevements. 



At the end of this period of convulsion, we find the domain 

 of the Alps, and the low plain which borders it on the north, 

 elevated above the level of the sea ; but this plain was in a 

 great measure covered with pools and marshes of fresh water, 

 in which the terrestrial animals of the period were destroyed. 

 It was then that there commenced the deposition of themolasse, 

 of that product of erosion and of the friction of the rocks 

 against one another, on the northern edge of the Alps. At 

 that period the northern side was probably flanked, as the 

 southern is at the present day, by a belt of porphyritic and ser- 

 pentinic rocks which have partly furnished the materials of the 

 nagelflue and of the molasse. 



The formation of the upper deposits of the molasse is the re- 

 sult of a new invasion of the Swiss plain by the sea ; but the 

 organic remains of that period do not the less prove the exist- 

 ence of lakes of fresh orbrackish water at the side of the sea shore. 

 The accumulation of the debris of rocks on the northern edge 

 of the Alps under the influence of a more violent action, and 

 the dispersion of a fine sand over the \>hole plain, terminate 

 the epoch of the nagelflue and of the molasse. 



A new dislocation of the Alpine surface took place between 

 the formation of the molasse and of the ancient diluvium, a 

 dislocation which appears to have been followed by the for- 

 mation of many of the valleys of subsidence in the Alps. In 

 consequence of this last soulevement, the secondary Alpine for- 

 mations were pressed against the tertiary strata, and the latter, 

 being elevated and broken up, acquired a more or less consider^ 

 able inclination. 



By placing this movement in connection with a general 

 soulevement of the Alpine system above the level of the sea. 



