Mr Stiuler on the Geological Slrue/ure of the Alps. 16S 



must therefore have emerged subsequently to the deposition of 

 this latter formation. 



The agencies, doubtless of very long duration, which have 

 operated on the Alpine sedimentary formations, have modi- 

 fied the original nature of the rocks, and transformed them 

 either into magnesian rocks (dolomite, talc-slate, chlorite- 

 slate, and serpentine), or into micaceous and felspathic rocks 

 (mica-slate, gneiss, and granite). 



These modifications were accompanied by an elevation of 

 the surface and a general change of position of the beds. It 

 is in the regions where the metamorphic agencies have ope- 

 rated with the greatest energy, that the formation took place 

 of those enigmatical fan-shaped arrangements, and of those 

 entanglements of felspathic, quartzose, and calcareous fossili- 

 ferous rocks. 



The modifications as well as the breaking up of the surface 

 have operated in various directions and at different epochs, 

 the consequence of which has been that the external direction 

 of the chains does not generally correspond with the direction 

 of the beds. There are not only longitudinal and transverse 

 valleys, but also longitudinal and transverse chains, diagonal 

 valleys and diagonal chains. 



The chief directions in Switzerland are : 1. From W.S.W. 

 to E.N.E. (more exactly from W. 23° S. to E. 23" N.), paral* 

 lei to the principal direction of the Alps. Examples : the 

 chain between the Diablerets and the AlteLs ; the great val- 

 leys of the Valais and of the Vorder Rhine. 



2. From S.W. to N.E. (more exactly from W. 37"* S. to E. 

 37° N.), parallel to the direction of the Alps of Savoy. Ex- 

 amples : the central group of the Finsteraarhorn and that of 

 Saint-Gothard ; the upper Valais ; the lake of Brienz. 



3. From S.S.W. to N.N.E. (more exactly from W. 53° S. 

 to E. 53° N.), parallel to the system of the Alps of Dauphiny. 

 Examples: The group of Mont Blanc ; the Italian lakes; the de- 

 pression between Briinig and KUssnach ; the eastern chain of 

 the Niesen. 



4. From S.S.E. to N.N.W. (more exactly from W. 60° N. 

 to E. 60° S.), parallel to Monte-Viso according to M. Elie de 

 Beaumont. It is the direction which prevails in the beds and 



