Ethiopia

Geography 

Ethiopia is a landlocked country occupying most of the Horn of Africa. It is bordered to the north and northeast by Eritrea, to the east by Djibouti and Somalia, to the south by Kenya, and to the west and southwest by (South)Sudan. The total area of Ethiopia excluding the disputed Ilemi triangle is 1,104,300 km2 of which only 0.7% is water. The terrain comprises a massive highland complex of mountains and plateaus (1,300 – 3,000 m above sea level) with central mountain range divided by the Great Rift Valley and surrounded by lowlands. The highest mountain in the Ethiopian Highlands occurs in Semien Mountains and reaches 4,533 m. The Danakil Depression within the Afar Triangle at -125m is the lowest point of Ethiopia. The Blue Nile, the chief headstream of the Nile by water volume, rises in T'ana Hayk (Lake Tana) in NW Ethiopia. Nearly all the large rivers comprising some 85% of its water flow northwestwards to the Nile. The chief river of Ethiopia flowing east is the Awash River, which rises in the Shewan uplands and runs out into the saline lacustrine district of the Afar Depression along the border with Djibouti.

Geology

Rocks of Precambrian age underlie large parts of northern and western Ethiopia and smaller areas in the south and east of the country. The Precambrian geology is poorly understood pending modern investigations but appears to comprise Archaen to Proterozoic metamorphic rocks, including granulites, all of which have been effected by the Neoproterozoic Pan African event. Ethiopia lies at the northern tip of the continental part of the East Africa Rift System. Voluminous piles of mainly Cenozoic volcanic rocks occur in large parts of western Ethiopia. Mesozoic and Cenozoic sediments occupy the east of the country unconformably overlying peneplaned basement.. The rift valley is covered with relatively young lacustrine sediments and volcanics. Volcanic rocks are more extensively developed in Ethiopia than anywhere else in the East African Rift and are most thickly developed in the central region and along a N-S axis situated immediately west of the main rift. The volcanics are characteristically alkaline, typified by fissure basalts of the Trap Series which can reach 2000m in thickness at the plateau-rift margin(s).