Africa's largest high roof split by a salt-lake rift
Little of the Ethiopian—or Abyssinian—Highlands falls below 1,500 metres, forming the continent's largest continuous elevated mass from Ethiopia into Eritrea. The Main Ethiopian Rift slices it into northwestern Semien and southeastern Harar massifs lined with salt lakes.
Simien Mountains National Park protects part of the Abyssinian Massif; Bale Zone peaks crown the Harar side above Ogaden and southern lowlands. In the south, medieval–early modern Kaffa exported coffee plants toward Arabia from forested high country—the commodity's namesake landscape.
The dome began rising some 75 million years ago as mantle magma pushed up ancient rocks of the Arabian-Nubian Shield. From around 30 million years ago, fissure eruptions stacked layer on layer of basalt into a flood plateau, and as the continental crust pulled apart the Great Rift Valley split the dome and raised large shield volcanoes. The northern highlands preserve four planation surfaces, the oldest formed no later than the Ordovician.
Height gives a tropical country a surprisingly temperate climate, and the mountains wring rain from Indian Ocean monsoon winds. Most major cities, including Addis Ababa and the old capitals Gondar and Axum, sit at about 2,000 to 2,500 metres. Montane forest grows between 1,100 and 1,800 metres, home to endemic birds such as Harwood's spurfowl and Prince Ruspoli's turaco; grassland and woodland, the largest ecoregion, spans 1,800 to 3,000 metres with junipers and Afrocarpus conifers; above that lie moorlands forming Africa's largest Afroalpine zone. Dense settlement on the lower slopes means grazing and even farming reach the high moorland.
Among the Amhara in the north, researchers have found genetic variants tied to breathing and hemoglobin levels, adaptations to thin air. Since the last ice age some Eurasian plants and animals have joined the region's Afromontane flora and fauna, while Sahelian acacia savanna to the northwest and East Sudanian savanna to the west ring the lower ground.
Source: Ethiopian Highlands
