The Ethiopian Highlands, also known as the Abyssinian Highlands, is a rough and uneven area of mountains that stretches from Ethiopia to Eritrea in Northeast Africa. This region covers the largest continuous area of such high elevation in the continent, with most of its surface above 1,500 meters (4,900 feet). The highest points reach up to 4,550 meters (14,930 feet). Because of its great height and wide area, the region is sometimes called the "Roof of Africa." Ethiopia is the only country in the area with such a highly elevated surface. This elevated land is cut diagonally by the Great East African Rift System, which runs from Syria to Mozambique across the East African Lakes. Most of the Ethiopian Highlands are located in central and northern Ethiopia, with the Eritrean Highlands forming the northernmost part of the region. The Ethiopia-Yemen Continental Flood Basalts are found in both the Horn of Africa and the highlands of Upper Yemen. These areas share cultural, historical, and genetic connections across the Red Sea.
History
In the southern parts of the Ethiopian Highlands, there was once a kingdom called Kaffa, a state from the medieval and early modern times. This region is where the coffee plant was sent to the Arabian Peninsula. The area where the kingdom once existed is mountainous and has areas with forests. The land is very fertile and can produce three harvests each year. The word "coffee" comes from the Arabic word "qahwah" and is connected to the region of Kaffa.
In the Amhara region to the north, scientists have found genetic changes in the Amhara people that help them adapt to low oxygen levels and high altitudes. These changes include a specific DNA variation linked to how hemoglobin works, a gene related to the body's daily cycles and response to low oxygen, and another gene strongly connected to how mammals manage oxygen levels. These adaptations may have developed within the past 5,000 years.
Physical geography
The Highlands are split into northwestern and southeastern areas by the Main Ethiopian Rift, which has several salt lakes. The northwestern area, called the Abyssinian Massif, includes the Semien Mountains. Part of this region has been made into the Simien Mountains National Park. The highest point there, Ras Dashen (4,550 m), is Ethiopia's tallest mountain. Lake Tana, which is the starting point of the Blue Nile, is also located in the northwestern part of the Highlands.
The southeastern area is called the Harar Massif. It is surrounded on the west by the fault line of the Rift Valley, on the east by the Ogaden Lowlands, and on the south by the Elkerie and Borena Lowlands. Its tallest mountains are found in the Bale Zone of Ethiopia's Oromia Region. The Bale Mountains, which have also been made into a national park, are almost as high as the Semien Mountains. This range is the main source of the Wabishebelle and Genalle (Juba) rivers. The mountains include peaks over 4,000 m. Examples are Mount Tullu Demtu (4,337 m), which is Ethiopia's second-highest major mountain, and Mount Batu (4,307 m).
Most of Ethiopia's major cities are found at heights of about 2,000–2,500 meters above sea level. These include Addis Ababa, Ethiopia's capital and largest city, and historic cities like Gondar and Axum.
Geology
The Ethiopian Highlands started to rise about 75 million years ago when hot rock from deep inside Earth pushed up a large dome made of old rocks from the Arabian-Nubian Shield. Later, the opening of the Great Rift Valley divided this dome into three sections. The mountains in the southern Arabian Peninsula are geologically connected to the Ethiopian Highlands but were separated by the splitting that formed the Red Sea and Gulf of Aden, which divided Africa from Arabia.
About 30 million years ago, a large flat area of rock began to form as layers of basalt lava poured out from cracks in Earth's surface. Most of these lava layers were tholeiitic, but some thin layers were alkali basalts, and smaller amounts of felsic volcanic rocks, like rhyolite, were also present. Toward the end of this lava-forming period, large explosive eruptions created calderas.
The Great Rift Valley eventually split the Ethiopian Highlands as Earth's crust stretched apart. This stretching caused large shield volcanoes made of alkaline basalt to form around 30–31 million years ago.
In the northern Ethiopian Highlands, there are four distinct planation surfaces. The oldest of these formed no later than the Ordovician Period. The youngest surface formed during the Cenozoic Era and is partially covered by the Ethiopia-Yemen Continental Flood Basalts. Unlike some areas of Africa, the planation surfaces in northern Ethiopia are not classified as pediplains or etchplains.
Climate
The way temperature spreads across Ethiopia is mainly influenced by altitude and latitude. Altitude is the most important factor that affects how temperature varies in different areas of Ethiopia. Ethiopia is located in the tropics, a region that receives the most sunlight, and every place there experiences the sun directly overhead twice each year. However, much of Ethiopia has highland areas, and their high altitudes lead to cooler, non-tropical temperatures. Ethiopia’s tropical climate is found in the lowland areas near the edges of the country. The main climate type in the Ethiopian Highlands is the Alpine climate.
Because the highlands raise Ethiopia’s elevation, even though the country is near the equator, it has a surprisingly mild climate. These highlands also capture rain from the monsoon winds coming from the Indian Ocean, causing a rainy season that lasts from June until the middle of September. These heavy rains lead to the Nile River flooding during the summer. This phenomenon confused ancient Greeks, as they were used to the Mediterranean climate, where summer is the driest season.
Ecology
The Ethiopian Highlands have plant and animal life similar to other mountain areas in Africa, known as Afromontane. However, since the last ice age, some plants from Eurasia (called palearctic) have also grown in this region. The Great Rift Valley divides the highlands, creating different habitats on either side.
At lower elevations, the highlands are surrounded by tropical savannas and grasslands. These include the Sahelian acacia savanna to the northwest and the East Sudanian savanna to the west.
The highlands are divided into three main ecoregions based on elevation. The Ethiopian montane forests are found between 1,100 and 1,800 meters, above the lowland grasslands and savannas. These forests extend into parts of Eritrea, Sudan, and Djibouti. This area once had many natural plant communities, but most have been turned into farmland. Kolla is a type of open woodland with trees like Terminalia, Commiphora, Boswellia, and Acacia. Weyna dega is a moister, higher woodland with conifers like Afrocarpus gracilior and Juniperus procera. The lower part of the Harenna Forest has an open canopy with trees such as Warburgia ugandensis, Croton macrostachyus, Syzygium guineense, and Afrocarpus gracilior, with wild coffee (Coffea arabica) as the main shrub. Rainfall from May to October and moisture from the Red Sea influence this area. Animals here include the Harwood's spurfowl (Pternistis harwoodi), Prince Ruspoli's turaco (Tauraco ruspolii), and yellow-throated seedeater (Serinus flavigula).
The Ethiopian montane grasslands and woodlands cover the area between 1,800 and 3,000 meters. Natural vegetation included forests in wetter areas and grasslands, bushland, and thicket in drier areas. However, much of this region has been converted to farmland due to fertile soil and human settlement. Cities in this area include Addis Ababa (Ethiopia’s capital), Bahir Dar, Harar, Ambo, Asella, Dodola, Bishoftu, Jimma, Nekemte, and Mek'ele. Awash National Park is a popular birdwatching site.
Drier areas still have some native plants, including conifers like Afrocarpus falcatus and Juniperus procera, along with Hagenia abyssinica. The Harenna Forest has moist, closed-canopy forests with Aningeria and Olea, covered in lianas and epiphytes. Above 2,400 meters, shrubs like Hagenia, Astropanax, and giant lobelias (Lobelia gibberroa) grow. The Semien Mountains have evergreen broadleaved forests dominated by Syzygium guineense, Arundinarial, Juniperus procera, and Olea africana.
Human activity, such as farming and livestock grazing, affects even high-altitude areas. Two protected moorland areas are Bale Mountains National Park (southern highlands) and Simien Mountains National Park (near Gondar), which includes Ras Dashen. These parks face habitat loss from grazing. Lower elevation parks, like Harar Wildlife Sanctuary, Awash National Park, Omo National Park, and Nechisar National Park, are even more vulnerable.
Above 3,000 meters, the high Ethiopian montane moorlands form the largest Afroalpine region in Africa. These areas are above the tree line and include grasslands and moorlands with many herbs and shrubs adapted to high altitudes. In Ethiopia, Afroalpine and Sub-Afroalpine vegetation is found in the Highlands of Semien and the Highlands of Bale.
Fauna
These slopes are home to many animals found only in this area, such as the endangered walia ibex (Capra walie) and the gelada baboon, which has thick fur that helps it live in the cool mountain climate. These two animals are only found on the northern side of the valley. Another rare animal, the mountain nyala (Tragelaphus buxtoni), lives only on the southern side and now survives at higher elevations than it originally did because farming has taken over the lower slopes. Other mammals found here include the mantled guereza (Colobus guereza), which is also in danger because its habitat is disappearing, as are the habitats of many other highland animals like the olive baboon (Papio anubis), Egyptian wolf (Canis lupaster), leopard (Panthera pardus), lion (Panthera leo), spotted hyena (Crocuta crocuta), caracal (Caracal caracal), serval (Leptailurus serval), common duiker (Sylvicapra grimmia), and giant forest hog (Hylochoerus meinertzhageni). Birds in the area include Rueppell's chat, the Ankober serin (Serinus ankoberensis), white-winged flufftail (Sarothrura ayresi), and blue-winged goose. The farmland is home to many butterflies, especially those in the groups Papilio, Charaxinae, Pieridae, and Lycaenidae.
Several animals in this region are found only here, including the critically endangered Ethiopian wolf (Canis simensis). Another endemic species is the big-headed mole-rat (Tachyoryctes macrocephalus), which is often seen on the Sanetti Plateau in the Bale Mountains. The mountain nyala sometimes moves to the high moorlands but is more commonly found at lower elevations. Birds that winter in the area include the wigeon (Anas penelope), shoveler (Anas clypeata), ruff (Philomachus pugnax), and greenshank (Tringa nebularia).
Other animals in the region include aardvarks, eagles, Egyptian wolves, secretarybirds, Nubian ibex, and marabou storks. Ethiopian endemic species found here are the shrew (Crocidura harenna), narrow-footed woodland mouse (Grammomys minnae), and Menelik's bushbuck (Tragelaphus scriptus meneliki), a subspecies known for its long, dark fur.