354 OF THE GEOLOGICAL 



across Abyssinia in the direction of these several 

 points, one effect of which (that of the great disinte- 

 gration of the material of the rocks along its course) 

 appears to me to have favoured the denudation 

 observed on the eastern and western borders of 

 this country. To this fracture I also attribute 

 the sudden curve of the Abi to the west, after 

 flowing nearly due south from lake Dembea ; the 

 physical barrier to its farther continuance in that 

 direction not being a ridge of hills, or what is 

 generally termed an anticlinal axis, but the presence 

 of the opposite wall of the disjointed rock, which 

 characterizes the extension of the fault across the 

 table land. This is neither unfounded assertion 

 nor rash conclusion, but the deliberate opinion I 

 have formed by a careful examination of the 

 mighty operations of nature that appear to have 

 acted upon the surface geography of Abyssinia from 

 the most remote ages. 



Let my reader return with me for a moment to 

 the country of Adal, an extensive plain, scarcely 

 one thousand feet high above the level of the sea. 

 Its river, the Ha wash, peculiarly its own, distinct in 

 the non-existence of opposite corresponding water- 

 sheds to identify it as having formed part of the 

 original surface level of the surrounding countries : 

 an intruder, in fact, between the opposite slopes of 

 the river Tacazza to the north and of the river 

 Whaabbee to the south ; the countries of which 

 were once continuous, but some convulsion 



