Albertine Rift, East African Rift (artificial rendering)

The Albertine Rift is the western branch of the

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of ...

, covering parts of

Uganda }), is a landlocked country in East Africa. The country is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the south by Tanzania. The ...

, the

Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

(DRC),

Rwanda Rwanda (; rw, u Rwanda ), officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of Central Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator ...

Burundi Burundi (, ), officially the Republic of Burundi ( rn, Repuburika y’Uburundi ; Swahili: ''Jamuhuri ya Burundi''; French: ''République du Burundi'' ), is a landlocked country in the Great Rift Valley at the junction between the African Gr ...

and

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...

. It extends from the northern end of Lake Albert to the southern end of

Lake Tanganyika Lake Tanganyika () is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. T ...

. The geographical term includes the valley and the surrounding mountains.

Geology

The Albertine Rift and the mountains are the result of tectonic movements that are gradually splitting the

Somali Plate The Somali Plate is a minor tectonic plate which straddles the Equator in the Eastern Hemisphere. It is currently in the process of separating from the African Plate along the East African Rift Valley. It is approximately centered on the isl ...

away from the rest of the African continent. The mountains surrounding the rift are composed of uplifted

Pre-Cambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

basement rock In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The baseme ...

s, overlaid in parts by recent

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...

Lakes and rivers

The northern part of the rift is crossed by two large mountain ranges, the Rwenzori Mountains between Lake Albert and Lake Rutanzige (formerly Lake Edward) and the Virunga Mountains between Lake Rutanzige and

Lake Kivu Lake Kivu is one of the African Great Lakes. It lies on the border between the Democratic Republic of the Congo and Rwanda, and is in the Albertine Rift, the western branch of the East African Rift. Lake Kivu empties into the Ruzizi River, whic ...

. The Virungas form a barrier between the

Nile Basin The Nile Basin is the part of Africa drained by the Nile River and its tributaries. Besides being the second largest hydrographic basin in Africa, the Nile Basin is effectively the most notable drainage basin on the continent. It covers approxi ...

to the north and east and the

Congo Basin The Congo Basin (french: Bassin du Congo) is the sedimentary basin of the Congo River. The Congo Basin is located in Central Africa, in a region known as west equatorial Africa. The Congo Basin region is sometimes known simply as the Congo. It con ...

to the west and south. Lake Rutenzige is fed by several large rivers, the Rutshuru River being one, and drains to the north through the Semliki River into Lake Albert. The Victoria Nile flows from

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after ...

into the northern end of Lake Albert and exits as the

White Nile The White Nile ( ar, النيل الأبيض ') is a river in Africa, one of the two main tributaries of the Nile, the other being the Blue Nile. The name comes from the clay sediment carried in the water that changes the water to a pale color ...

from a point slightly to the west, flowing north to the Mediterranean. South of the Virungu, Lake Kivu drains to the south into Lake Tanganyika through the

Ruzizi River The Ruzizi (also sometimes spelled Rusizi) is a river, long, that flows from Lake Kivu to Lake Tanganyika in Central Africa, descending from about to about above sea level over its length. The steepest gradients occur over the first , where ...

. Lake Tanganyika then drains into the

Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire River, is the second longest river in Africa, shorter only than the Nile, as well as the second largest river in the world by discharg ...

via the

Lukuga River The Lukuga River is a tributary of the Lualaba River in the Democratic Republic of the Congo (DRC) that drains Lake Tanganyika. It is unusual in that its flow varies not just seasonally but also due to longer term climate fluctuations. Location ...

. It seems likely that the present hydrological system was established quite recently when the Virunga volcanoes erupted and blocked the northward flow of water from

into

Lake Edward Lake Edward (locally Rwitanzigye or Rweru) is one of the smaller African Great Lakes. It is located in the Albertine Rift, the western branch of the East African Rift, on the border between the Democratic Republic of the Congo (DRC) and Uganda, ...

, causing it instead to discharge southward into Lake Tanganyika. Before that Lake Tanganyika, or separate sub-basins in what is now the lake, may have had no outlet other than evaporation. The Lukuga has formed relatively recently, providing a route through which aquatic species of the Congo Basin could colonize Lake Tanganyika, which formerly had distinct fauna.

Mountains

From north to south the mountains include the Lendu Plateau, Rwenzori Mountains, Virunga Mountains and Itombwe Mountains. The Ruwenzori mountains have been identified with Ptolemy's "Mountains of the Moon". The range covers an area long by wide. This range includes Mount Stanley , Mount Speke and

Mount Baker Mount Baker ( Lummi: '; nok, Kw’eq Smaenit or '), also known as Koma Kulshan or simply Kulshan, is a active glacier-covered andesitic stratovolcano in the Cascade Volcanic Arc and the North Cascades of Washington in the United States. ...

. The Virunga Massif along the border between Rwanda and the DRC consists of eight volcanoes. Two of these,

Nyamuragira Nyamuragira, also known as Nyamulagira, is an active shield volcano in the Virunga Mountains of the Democratic Republic of the Congo, situated about north of Lake Kivu. The name is derived from the Bantu verb ''Kuragira nyamu'', meaning to ' ...

and Nyiragongo, are still highly active. Isolated mountain blocks further to the south include Mount Bururi in southern Burundi, the Kungwe-Mahale Mountains in western Tanzania, and Mount Kabobo and the Marungu Mountains in the DRC on the shores of

. Most of the massifs rise to between and .

Ecology

The

Albertine Rift montane forests The Albertine Rift montane forests is a tropical moist broadleaf forest ecoregion in east-central Africa. The ecoregion covers the mountains of the northern Albertine Rift, and is home to distinct Afromontane forests with high biodiversity. G ...

are important eco-regions. Transitional forests, intermediate between lowland and montane forest, are found at elevations from around to . Montane forest covers the slopes from around to . Above there are areas of bamboo and elfin forest. Heather and grasses predominate above . The ecology is threatened by deforestation as a growing population seeks new farmland. Illegal timber extraction is another problem, and artisanal gold mining causes some local damage.

References

Sources