The Great Rift Valley of East Africa – Beloved Planet

The East African Rift Valley (or the Great Rift Valley) is a massive geological structure, a system of tectonic faults that stretches across East Africa and Asia. The valley was formed by the movement of lithospheric plates and active volcanism.

Great Rift Valley

The Great Rift Valley (East African Rift Valley) is a huge rift valley that stretches deep into East Africa from northern Ethiopia to the central province of Mozambique. The contours of the Great Rift Valley are like a crude slingshot.

The East African Rift Valley is considered the cradle of humanity, as some of the oldest remains of modern human ancestors have been found here. In particular, finds in Olduvai Gorge (Tanzania) and the Lake Turkana region (Kenya) have provided important data on early human evolution.

Geography and history

This massive structure was named in the late 19th century by the British geologist and explorer John Walter Gregory (1864-1932), who was famous for his studies of the geography and geology of East Africa and Australia. Red Sea The eastern shore of Lake Nyasa is named the Gregory Rift in honor of the scientist himself, while the short western branch is known as the Albertine Rift.

The Great Rift Valley of East Africa was formed by tectonic activity at the boundary between the African and Arabian plates, and the northern part of the valley was filled with water, forming the Red Sea.

Rift valley – an elongated depression in the Earth’s crust, usually very large, formed along fault lines in the crust when tensile or longitudinal forces act on it (either in the ocean or on land). It is correct to talk about the East African Rift System, because in different parts and sections of it, the continental belts of the Earth’s crust are expanding and contracting. In the rift system, there are also areas where oceanic crust has been formed. An example of such a part of the Great Rift Valley is the Afar Valley in Ethiopia, located in the northern part of the rift zone.

As a result of the constant movement of the Earth’s crust, the deepest depression in Africa has been formed here, with a depth of 1,500 meters below sea level. The topographical features combined with the climatic features make this one of the hottest places on Earth: the average minimum temperature in the Afar Valley is +25°C, the maximum is +35°C, and the annual precipitation is about 200 mm. The depression was formed about 1.5-2 million years ago, at the beginning of the Quaternary period. On the edge of the depression are the tops of volcanoes, including active volcanoes such as Dabahu (1,442 meters), which became famous due to the eruption in 2005 and previous earthquakes that caused a crack in the Earth’s crust – the “Dabahu Fault”. Researchers believe that it is this crack that indicates the direction in which the Somali tectonic protoplate will separate from the African protoplate, eventually splitting the African continent in two.

The Afar Valley, also known as the Afar Basin, is also known as the “tectonic triangle”: the Red Sea Rift, the East African Rift and the Aden Ridge meet here. The basin is subject to constant tectonic movement (1-2 cm per year) and is the second place in the world (after Iceland) where the ridges can be studied directly on land. The Afar Basin is famous for the most unique volcano on Earth – Erta Ape, a shield volcano that is the most active volcano in Ethiopia (it is worth noting that it has been active since 1976) and the only volcano in the world with two lava lakes.

The Great Rift Valley of East Africa contains the highest peak in Africa, Mount Kilimanjaro, and a huge crater. Ngorongoro (Tanzania), formed by the collapse of a large volcano 2.5 million years ago. The crater is 610 meters deep, 17 to 21 kilometers in diameter, and has a total area of ​​about 265 square kilometers.

The East African Rift Valley region is home to several volcanoes, the tallest of which are the extinct volcanoes of Kenya, Mount Kilimanjaro and Mount Elgon. Also in northwestern Rwanda is Volcanoes National Park, an example of these stunning, naturally formed, large volcanic formations, with Mount Karisimbi, Mount Bisoke, Mount Muhabura, Mount Gashinga and Mount Sabinyo all within the park.

Modern science links the initial stages of the evolution of the ape-human branch to the Great Rift Valley of East Africa. In particular, the Afar Basin, where the oldest human remains have been found – Australopithecus afar, who lived about 4 million years ago. In 1913, German geologist Hans Leake first explored Olduvai Gorge, west of the Giant Crater Highlands in Tanzania. The scientist brought back a large number of fossil mammal remains from there. In 1928, British anthropologist Louis Leakey (1903-1972) examined these remains and found that some of the materials Leake brought back were artifacts – man-made objects. Leakey traveled to Olduvai Gorge, but it was not until 1959 that he discovered skulls of modern human ancestors, including one belonging to the genus Homo. Leakey called it Homo habilis – “man of great skill”. Later, the remains of other hominins were discovered, ranging in age from 500,000 to 1.8 million years old.

According to scientists’ calculations, in the future East Africa will be separated from the main body of the African continent by a fault, forming an island and extending in the direction of the Arabian Peninsula. When the Arabian Peninsula collides with the East African island, mountains will form and the Red Sea will become three times longer. Scientists say this will definitely happen in 3 to 4 million years, and the main fault line will run exactly along the current East African Rift Valley. Researchers are convinced that Africa is splitting at a speed rarely seen in geology.

African Great Lakes

The Great African Lakes are a natural part of the rift system formed during the geological formation of the East African Rift Valley.

Tanganyika is the longest freshwater lake in the world: about 700 kilometers long. Lake VictoriaLocated in the tectonic trough of the East African Platform, between the western and eastern branches of the Rift Valley, it is the world’s second largest freshwater lake (after Lake Superior): 68,000 km². Lake Nyasa is the third largest and southernmost of the East African Rift Valley lakes, filling a nearly 600 km deep Meridiani depression in the crust between Malawi, Mozambique and Tanzania. Sediments at the bottom of the lake are up to 4 km thick: the lake is millions of years old. Lake Edward is the smallest of the African Great Lakes and was temporarily renamed in the 1970s after the brutal Ugandan dictator Idi Amin. The other three lakes are Lake Albert, Lake Kivu and Lake Rudolf (Lake Turkana).

nature

The area through which the Great Rift Valley passes is the richest in flora and fauna in the whole of Africa. The world-famous Urunga National Park (Democratic Republic of Congo), Rwenzori National Park, Queen Elizabeth National Park (Uganda) and Volcanoes National Park in Rwanda were established to protect wildlife. The Serengeti ecosystem is of world significance, being one of the oldest and best preserved protected areas on Earth. More than 80% of the Serengeti is covered by protected areas: Serengeti National Park, Ngorongoro Conservation Area in Tanzania and Maasai Mara Reserve in Kenya.

General information

• Location: East Africa.
• Countries and regions (from south to north): Mozambique, Malawi, Tanzania, Zambia, Democratic Republic of the Congo, Burundi, Rwanda, Uganda, Kenya, Ethiopia, Eritrea, Djibouti, Somalia.
• Main rivers: Congo, Zambezi RiverWhite Nile.
• Major lakes: Lake Nyasa, Lake Tanganyika, Lake Victoria, Lake Edward, Lake Albert, Lake Kivu, and Lake Rudolf.
• Mountain systems: Ethiopian Highlands, Rwenzori Mountains, Virunga Mountains, Itumbwe Mountains, Aberdare Mountains.
• Length (from south to north): about 6,000 kilometers.
• Width: 30 to 100 km.
• Depth: several hundred meters to several thousand meters.
• Highest point: Kilimanjaro (Tanzania, 5895 m).
• Lowest point: -153 m (Afar Valley).
• Other peaks: Ras Dashen (Ethiopia, 4620 meters), Mount Kenya (Kenya, 3825 meters), Mount Sapitwa (Mlanje, Malawi, 3002 meters).

Climate and Weather

• Climate (from north to south): tropical, equatorial, tropical again.
• Average annual temperature: +22 to +25°C.
• Average annual precipitation: 700-800 mm in plains and 2500-3500 mm in mountainous areas.
• Relative humidity: 60-80%.

Attractions

• The great African lakes (Lake Nyasa, Lake Tanganyika, Lake Victoria, Lake Edward, Lake Albert, Lake Kivu, Lake Rudolf).
• Afar Valley and Afar Basin.
• Erta Ale volcano and its lava lake.
• Mount Dabahu.
• Kilimanjaro.
• Ngorongoro Crater.
• Urunga National Park (Democratic Republic of Congo), Rwenzori National Park and Queen Elizabeth National Park (Uganda) and Volcanoes National Park in Rwanda.
• Serengeti Ecosystem (Serengeti National Park, Ngorongoro Conservation Area, Tanzania, Maasai Mara Reserve).
• Olduvai Gorge.

Interesting Facts

• In the area of ​​the chain of active volcanoes on the edge of the Afar Valley, a team of seismologists has been conducting research in search of extremophiles – organisms that can survive and reproduce in conditions of the highest temperatures (only bacteria and microorganisms have been found so far). Organisms that survive at temperatures between +45 and +113°C are called thermophiles.
• The lakes of the Gregory Rift (eastern) are surrounded by land and gradually become shallower. Due to evaporation, large amounts of salt are deposited on the bottom of the lakes. Thus, a salt layer up to 40 meters thick is formed on the bottom of Lake Magadi (Kenya), and the dried-up areas are covered with layers of the purest rock salt.
• In the East African Rift Valley there is a volcano called Ol Doinyo Lengai (Tanzania, 2962 m above sea level). The volcano’s strange appearance is due to the fact that when it erupts, it carries ash and carbonates outside. When the carbonates come into contact with moisture in the air, they turn into sodium carbonate, so what looks like snow on top of the volcano is actually white ash.
• There is life within a depth of about 200 meters in Lake Tanganyika, but below 200 meters the concentration of hydrogen sulfide is very high and there is no life all the way to the bottom of the lake.
• Some of the oldest remains of our ancestors were found in the valley, such as the famous “Lucy” skeleton (Australopithecus afarensis) found in Ethiopia.
• “Nyasa” is the Yao language, meaning “lake”. Lake Tanganyika It means “water full of fish” in the language of the Bembe people.