196 GEOLOGY. 



From the small opportunity that was afforded of exa- 

 mining this formation, nothing can be added to what is 

 already known of it. 



Soils of the Abyssinian Highlands. — The great fer- 

 tility of Central and Southern Abyssinia, the home, from 

 time immemorial, of one of the few African nations 

 which have risen above the savage state, is doubtless 

 due, in a great measure, to the prevalence of trap rocks. 

 Upon the sandstones and limestones of Tigre vegetation 

 is poor and sparse ; on the metamorphic rocks the soil 

 is better ; but it is only on the traps, or in tbeir neigh- 

 bourhood, tbat it is really rich. 



The most interesting circumstance connected with the 

 Abyssinian soils is, that wherever basaltic rocks prevail 

 there is found a very fertile, somewhat argillaceous soil, 

 black or dark brown in colour, opening into cracks in 

 hot weather, and in every way resembling the well- 

 known "regur" of Central, Western, and Southern 

 India. Precisely as in India, moreover, this soil appears 

 peculiarly suited to the growth of grasses and cereals,^ 

 but less adapted for forest, perhaps because the luxuriant 

 grass chokes the growth of the larger plants. This soil 

 does not appear to be met with far from basaltic rocks, 

 although plains of it may occur upon other formations, 

 as at Buya, the site of the British camp near Antalo. In 

 this and similar cases, it is highly probable that the soil 

 has been derived from the traps which cap the neigh- 



' Wherever the climate is sufBciently warm, this soil is doubtless admirably 

 suited for cotton also. So much is this the case in India, that the soil in 

 question is commonly known as " cotton soil." 



