152 



OUTLINES OF FIELD-GEOLOGY 



PART I 



markable example which occurs in the mass of the Glar- 

 nisch, one of the eastern Swiss Alps, as described by Dr. 



FIG. 50. Rcflexed contortions or isoclinal folds. 



Baltzer. The peak (Ruchen) reaches a height of 2107 

 metres above the valley to the left of it (Klonthal). I lie- 

 folded rocks belong to the Cretaceous system of the Alps. 

 Cleavage. By the powerful lateral pressure to which 

 rocks have been subjected during their subsidence and 

 contortion, their minute particles, which usually present 

 one axis longer than the others, have been compelled 

 to adjust themselves in the rock along lines of 



FIG. 51. Sc< 



>n of the grand inversions of strata 

 Eastern Alps. 



n the Glarnisch Mountain, 



resistance ; that is, with their longer axis perpendicular 

 to the direction of the pressure. Mr. Sorby showed by 

 ingenious experiments, that with suitable adjustments of 

 pressure this re-arrangement could be imitated artificially 



