Everything about The Ethiopian Highlands totally explained
The
Ethiopian Highlands are a rugged mass of mountains in
Ethiopia,
Eritrea (which is sometimes referred to as the
Eritrean Highlands), and northern
Somalia (
Somaliland) in northeastern
Africa. The Ethiopian Highlands form the largest continuous area of its altitude in the whole continent, with little of its surface falling below 1500 m (5000 ft), while the summits reach heights of 4600 m to 4900 m (15,000 to 16,000 ft). It is sometimes called the
Roof of Africa for its height and large area it covers.
Geography
The Highlands are divided into northwestern and southeastern portions by the
Great Rift Valley, which contains a number of salt lakes. The northwestern portion, which covers the
Tigray and
Amhara Regions, includes the
Semien Mountains, part of which has been designated a
national park. Its highest peak,
Ras Dashan (4533 m), is the highest peak in Ethiopia and the fourth-highest in Africa.
Lake Tana, the source of the
Blue Nile, also lies in the northwestern portion.
The southeastern portion's highest peaks are located in the
Bale Zone of Ethiopia's
Oromia Region. The
Bale Mountains, also designated a
national park, are nearly as high those of Semien, with peaks over 4000 m, such as
Tullu Demtu (4337 m and the second-highest peak in Ethiopia) and
Batu (4307 m).
Geology
The Ethiopian Highlands began to rise 75 million years ago, as magma from the earth's mantle uplifted a broad dome of the ancient rocks of the
African Craton. The opening of the
Great Rift Valley split the dome of the Ethiopian Highlands into three parts; the mountains of the southern
Arabian Peninsula are geologically part of the ancient Ethiopian Highlands, separated by the rifting which created the
Red Sea and
Gulf of Aden and separated Africa from Arabia.
Around 30 million years ago, a
flood basalt plateau began to form, piling layers upon layers of voluminous fissure-fed
basaltic lava flows. Most of the flows were
tholeiitic balts, save for a thin layer of alkali basalts and minor amounts of
felsic (high-silica) volcanic rocks, such as
rhyolite. In the waning stages of the flood basalt episode, large explosive
caldera-forming eruptions also occurred.
The Ethiopian Highlands eventually became bisected by the
Great Rift Valley, as the African continental crust pulled apart. This rifting gave rise to large
alkaline basalt
shield volcanoes beginning about 30-31 million years ago.
Ecology
Because the highlands elevate Ethiopia, located close to the
equator, this has resulted in giving this country an unexpectedly temperate
climate. Further, these mountains catch the precipitation of the
monsoon winds of the
Indian Ocean, resulting in a
rainy season that lasts from June until mid-September. These heavy rains cause the
Nile to flood in the summer, a phenomenon that puzzled the
ancient Greeks.
The Ethiopian Highlands share a similar flora and fauna of other mountainous regions of Africa; this distinctive flora and fauna is known as
Afromontane. The Highlands are home to a number of
endemic species, such as the
Walia Ibex and
Ethiopian Wolf.
At lower elevations, the highlands are surrounded by
tropical savannas and grasslands, including the
Sahelian Acacia savanna to the northwest, the
East Sudanian savanna to the west, and the
Somali Acacia-Commiphora bushlands and thickets to the northeast, east, south, and through the Rift Valley.
The highlands themselves are divided into three distinct ecoregions, distinguished by elevation. The
Ethiopian montane forests lie between 1,100 and 1,800 meters elevation, above the lowland grasslands and savannas. This woodland belt has several plant communities.
Kolla, is an open woodland found at lower elevations, and dominated by species of
Terminalia, Commiphora, Boswellia, and
Acacia.
Weyna dega is a woodland found in moister and higher locations, dominated by the
conifers
Afrocarpus gracilior and
Juniperus procera. The lower portion of the Harenna forest is a distinct woodland community, with an open canopy of
Warburgia ugandensis,
Croton macrostachyus, and
Syzygium guineense, and
Afrocarpus gracilior, with
wild coffee (Coffea arabica) as the dominant understory shrub.
The
Ethiopian montane grasslands and woodlands occupies the area between 1800 and 3000 meters elevation. The natural vegetation was closed-canopy forest in moister areas, and grassland, bushland, and thicket in drier areas. A few areas of natural vegetation remain. Drier areas covered with forests of the forest consists of
Podocarpus falcatus and
Juniperus procera, often with
Hagenia abyssinica. In the Harenna forest, pockets of moist, closed-canopy forest with
Aningeria and
Olea are draped with
lianas and
epiphytes, while above 2400 meters, a shrubby zone is home to
Hagenia,
Schefflera, and giant
lobelias. The evergreen broadleaved forest of the
Semien Mountains, between 2,300 and 2,700 meters elevation, is dominated by
Syzygium guineense,
Juniperus procera, and
Olea africana.
Above 3000 meters elevation lie the
Ethiopian montane moorlands, the largest
afroalpine region in Africa. The montane moorlands lie above tree line, and consists of grassland and
moorland with abundant herbs and some shrubs. The Ethiopian Wolf is endemic to the montane moorlands, and is critically endangered.
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