188 GEOLOGY. 



rounded hummocks of a very peculiar shape. Many- 

 more of similar form occur to the westward, and the 

 range near Adowa presents a very similar appearance, 

 and consists, in aU probability, of the same rock. 



These traps rest in places upon the metamorphics, 

 but in general upon the Adigrat sandstones, to which 

 they are quite unconformable. Although they are not 

 generally bedded, there is in places, as on Akub Teriki 

 hUl, an appearance of distinct strata; and the various 

 trachyte hills to the south, towards Guna Guna and 

 Fokada, have much the appearance of being the remnants 

 of one thick lava flow. 



Taking into consideration their different mineral 

 character and mode of accumulation, the Adowa and 

 Senafd traps have much the appearance of belonging to 

 a distinct group from the beds of Ashangi, Magdala, and 

 Adigrat, and their much greater apparent unconformity 

 to the sandstones beneath would favour the idea of their 

 being more recent than the rocks of the Adigrat hUls. 

 If they be so, then their age must be very much less, 

 for there can be but little doubt that the traps of the 

 Adigrat hUls had formerly a much greater horizontal 

 extension : they are doubtless merely the remains oi 

 beds which once covered the whole country to a depth 

 probably of 2,000 or 3,000 feet, and all of these must 

 have been swept away again at Senafd before the volcanic 

 formations of Akub Teriki and the neighbouring hdls 



in this matter. Where the rock is slightly decomposed, as it generally is, it 

 is almost impossible to distinguish it from an argUlaceous sandstone. Dr. 

 BiippeU took these rocks for hardened marl. 



