164 QWLOGY. 



SECTION III. 



METAMORPHICS. 



The whole mass of the plateau of Northern Abyssinia, 

 as far south as the neighbourhood of Antalo at least, 

 consists of metamorphic rocks, capped only by sedi- 

 mentary and volcanic formations. 



As is usual in countries where altered formations are 

 largely developed, the metamorphics of Abyssinia vary 

 greatly in mineral character. The variation is, indeed, 

 greater than usual, every intermediate grade being found 

 between the most . coarsely crystalline granite and a 

 slaty rock so little altered that the lines of the original 

 bedding are still apparent. 



Perhaps the most prevalent form of rock is a rather 

 finely crystalline gneiss. Hornblende-schist and mica- 

 schist are met with, but neither of the minerals from 

 which they are named appears to be so abundant as in 

 some metamorphic tracts. On the other hand, a compact 

 felspathic rock, approaching felsite in composition, is 

 prevalent in places, as in the Suru defile, between 

 Komayli and Senaf^. Bands of quartzite were not so 

 abundant as usual in the country traversed. 



