7. Identify the major topographical units of Ethiopia and its sub units? (Not less than 10 pages
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Answer:
Between the valley of the Upper Nile and Ethiopia's border with Sudan and South Sudan is a region of elevated plateaus from which rise the various tablelands and mountains that constitute the Ethiopian Highlands. On nearly every side, the walls of the plateaus rise abruptly from the plains, constituting outer mountain chains. The highlands are thus a clearly marked geographic division. In Eritrea, the eastern wall of this plateau runs parallel to the Red Sea from Ras Kasar (18° N) to Annesley Bay (also known as the Bay of Zula) (15° N). It then turns due south into Ethiopia and follows closely the line of 40° E for some 600 km (373 mi).
About 9° N there is a break in the wall, through which the Awash River flows eastward. The main range at this point trends southwest, while south of the Awash Valley, which is some 1,000 m (3,281 ft) below the level of the mountains, another massif rises in a direct line south. This second range sends a chain (the Ahmar Mountains) eastward toward the Gulf of Aden.
The two chief eastern ranges maintain a parallel course south by west, with a broad upland valley in between – in which valley are a series of lakes – to about 3° N, the outer (eastern) spurs of the plateau still keeping along the line of 40° E. The southern escarpment of the plateau is highly irregular, but has a general direction northwest and southeast from 6° N to 3° N. It overlooks the depression in which is Lake Turkana and – east of that lake – the southern Debub Omo Zone (part of the larger Southern Nations, Nationalities, and Peoples Region).
The western wall of the plateau from 6° N to 11° N is well marked and precipitous. North of 11° N the hills turn more to the east and fall more gradually to the East Sudanian savanna plains at their base. On its northern face, the plateau falls in terraces to the level of the eastern Sudan.
The eastern escarpment is the best defined of these outer ranges. It has a mean height of 2,100 to 2,400 m (6,890 to 7,874 ft), and in many places rises almost perpendicularly from the plain. Narrow and deep clefts, through which descend mountain torrents that lose themselves in the sandy soil of the Eritrean coast, afford means of reaching the plateau, or the easier route through the Awash Valley may be chosen. On surmounting this rocky barrier, the traveller finds that the encircling rampart rises little above the normal level of the plateau.
The physical aspect of the highlands is impressive. The northern portion lies mainly between 10° and 15° N. It consists of a huge mass of Archaean rocks with a mean height of 2,000 to 2,200 m (6,562 to 7,218 ft) above sea level, and is flooded in a deep central depression by the waters of Lake Tana. Above the plateau rise several irregular and generally ill-defined mountain ranges which attain altitudes of from 3,700 m (12,139 ft) to just under 4,600 m (15,092 ft). Many of the mountains are of unusual shape.
Characteristic of the country are the enormous fissures which divide it, formed over time by the erosive action of water. They are the valleys of the rivers, which rising on the uplands or mountain sides, have cut their way to the surrounding lowlands. Some of the valleys are of considerable width; in other cases the opposite walls of the gorges are but two or three hundred meters apart, and fall almost vertically thousands of meters, representing an erosion of many hundred thousands cubic metres of hard rock. One result of the action of the water has been the formation of numerous isolated flat-topped hills or small plateaus, known as ambas, with nearly perpendicular sides.
The highest peaks are found in the Semien and Bale ranges. The Semien Mountains lie northeast of Lake Tana and culminate in the snow-covered peak of Ras Dashen, which has an altitude of 4,550 m (14,928 ft). A few kilometers east and north respectively of Ras Dashen are Mounts Biuat and Abba Yared, whose summits are less than 100 meters (328 ft) below that of Ras Dashen.
The Bale Mountains are separated from the larger part of the Ethiopian highlands by the Great Rift Valley, one of the longest and most profound chasms in Ethiopia. The highest peaks of that range include Tullu Demtu, the second-highest mountain in Ethiopia (4,377 m or 14,360 ft), Batu (4,307 m or 14,131 ft), Chilalo (4,036 m or 13,241 ft) and Mount Kaka (3,820 m or 12,533 ft).
Parallel with the eastern escarpment are the heights of Biala, 3,810 m (12,500 ft), Mount Abuna Yosef, 4,190 m (13,747 ft), and Kollo, 4,300 m (14,108 ft), the last-named being southwest of Magdala. Between Lake Tana and the eastern hills are Mounts Guna, 4,210 m (13,812 ft), and Uara Sahia, 3,960 m (12,992 ft). In the Choqa Mountains of Misraq Gojjam, Mount Choqa (also known as Mount Birhan) attains a height of 4,154 m (13,629 ft).
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