high res (1.3 M) low res (112 K)

ISS016-E-010784 (16 Nov. 2007) --- Semien Mountains, Gonder, northern Ethiopia are featured in this image photographed by an Expedition 16 crewmember on the International Space Station.

The Semien Mountains, the highest parts of the Ethiopian Plateau (above 2,000 meters--6,560 feet), are surrounded by a steep, ragged escarpment (step) with dramatic vertical cliffs, pinnacles, and rock spires - scenery that draws international tourists. Included in the range is the highest point in Ethiopia, Ras Dashen at 4,533 meters (14,926 feet) - an altitude only recently computed with any accuracy. The plateau and surrounding areas are made up of numerous flood basalts, totaling probably more than 3,000 meters in thickness. According to scientists, the lavas erupted quickly (in about one million years) 31 million years ago, as Ethiopia passed above what is known as the Afar "hotspot."

The hotspot caused the general region of Ethiopia to be elevated, which encouraged extensive river erosion. This erosion has cut the highly dramatic canyons that ring the plateau. Although the plateau lies in the latitude of the Sahara--Arabia deserts, its great altitude makes for a cool, wet climate.

This is shown by light green vegetation, compared with the brown canyons which are hot and dry. The green tinge on the biggest escarpment (trending across the top third of the image) is also vegetation, showing that this part of the escarpment also receives more rain than other parts of the escarpment wall.

The Semien Mountains are one of the few places in Africa to regularly receive snow, and they receive plentiful rainfall (more than 1,280 millimeters--55 inches). A major canyon cuts the flatter plateau surface (center), with several more surrounding the plateau. These canyons are hot because they reach low altitudes, more than 2,000 meters below the plateau surface. The Semien Mountains National Park has been declared a World Heritage Site by UNESCO for its rugged beauty.

In addition, several extremely rare species are found here, such as the Gelada baboon with its thick coat to protect against the cold; the critically-endangered Walia ibex with long, heavy scimitar-like horns; and the Ethiopian wolf--also known as the Semien jackal, the "most endangered canid."

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