134 



NORTH-EAST AEEICA, 



Fi-. 45.- 



-Lakes of East Abyssinia. 

 Scale 1 : 1,500,000. 



reddish clay. E,ed is the normal colour of the Abyssinian rocks, the very veins 

 of quartz being often of a pink hue, caused by the oxide of iron. According to 

 Heuglin, at least one of the craters, from which were formerly ejected the Hamasen 

 lavas, has been perfectly preserved. Rising midway between Keren and Adua to a 



height of about 400 feet, it is stated to 

 present the appearance of a crater but 

 recently extinct, although Rohlfs, follow- 

 ing the same route, failed to discover it. 

 To the south, on the eastern edge of the 

 plateau, rise the isolated cones of other 

 volcanoes. Some of the Tigré crests 

 are veritable mountains, not merely in 

 absolute altitude, but also in their eleva- 

 tion relative to the surrounding plains. 

 Thus east of Adua, the cleft cone of Sema- 

 yata attains a height of 10,306 feet, or 

 over 3,000 feet above the town occupying 

 a depression of the plateau at its base. 

 Eastwards, near the outer ledge of the 

 uplands, are other lofty hills, one of which, 

 Aleqwa, rises to a height of 11,250 feet. 

 To the west, between the Mareb and Tak- 

 kazeh, the plateau gradually falls, the 

 relative heights of the mountains dimin- 

 ishing in proportion. 



The loftiest headland of northern 

 Abyssinia is separated from Tigré in the 

 north and east by the semicircular gorge 

 of the Takkazeh, while the affluents of 

 this great river encircle the plateau on 

 the south-west, thus isolating the Simen 

 (Samen, Semen, Semien, or Semieneh), 

 that is the " northern " or " cold region." 

 The mean height of its escarpments ex- 

 ceeds 10,000 feet, whilst the surrounding 

 valleys of the Balagas to the south and of 

 the Takkazeh to the north, are respectively 

 5,000 and 6,000 feet lower. Hence the 

 waters flowing from the snowy Simen 

 uplands have a very rapid course, in many 

 places broken by cascades. One of these cataracts Heuglin describes as falling some 

 1,500 feet into a chasm which appears to have been a crater partly destroyed by 

 erosion. Like most of the other fragments of the Abyssinian plateau properly so- 

 called, the Simen uplands consist entirely of volcanic, basaltic, trachytic, phonolithic. 



39"iO 



[• . of Greenwich 59°40' 



30 Miles. 



