THE ABYSSINIAN PLATEAU. 129 



west, a mean altitude of about 8,000 feet. All the regions attaining or exceeding 

 this height are called dega, a term analogous to the Persian sarhad and Arab nejd. 

 Below the altitude of 6,000 feet, the intermediate valleys and gorges dividing the 

 plateau, excavated by the mountain torrents to various depths, take the name of 

 kivalla, holla, or kulla, a zone of " hot lands " corresponding to the ghermsir of 

 Persia, or to the tehamas of Arabia. Between these two zones stretches the voina- 

 dega, or temperate region. In many places the rugged escarpments present a 

 sudden contrast between the degas and the kwallas, the difference of their relief 

 being heightened by that of their climate and vegetation. The cataracts, such as 

 that of Davezut, near Debra-Tabor, fall either in a single sheet or through a suc- 

 cession of rapids from one zone to another. Most of the partial granite or basalt 

 masses of the plateau have outer walls formed of cliffs and superimposed talus, 

 which give the hills the appearance of step-pyramids; but some of these kwallas 

 are little more than fissures or gorges, like the North American cations. Such 

 chasms appear to be but a stone's throw across ; their true size, however, can only 



Fig. 41. — Profile of Abyssinia from East to West. 

 Scale 1 : 6,000,000. 



37°L 1 di breenwich 



The scale of heigrhts is 250 times larger than that of distances. 

 ■ 6 Miles. 



be seen on descending into the abyss, walking for hours on the edge of giddy 

 precipices, crossing the torrents at the bottom, and then scaling their abrupt sides. 

 The defiles are occasionally blocked by masses of rock swept down by the mountain 

 torrents, and presenting serious obstacles to the local trafific. The most remark- 

 able ravines occur along the eastern edge of the plateau, where the total fissure 

 exceeds 6,500 feet, measured from the summit of the degas down to the sea-level. 

 Nowhere else can a more convincing proof be observed of the erosive action of 

 running waters. The two walls of certain gorges, rising nearly vertically within 

 a few feet of each other to a height of some hundreds of feet, represent an erosion 

 of hard rock amounting to at least ten thousand five hundred million cubic feet. 

 Nevertheless, the waters have regulated the fall of the channel, which averages not 

 more than one in forty yards. This incline is easily ascended, but several of the 

 defiles remain blocked for months together by the mountain torrents ; every year 

 new paths have to be formed across the débris, while some have had to be entirely 

 abandoned. The route to Kumaili, through which the English army marched to 

 the Abyssinian plateau, had probably not been occupied by a military force since 



9— AF. 



