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. It was formerly considered to be part of a l ...

, covering parts of

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It 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 ...

, the

Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

(DRC),

Rwanda Rwanda, officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of East Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator, Rwanda is bordered by ...

Burundi Burundi, officially the Republic of Burundi, is a landlocked country in East Africa. It is located in the Great Rift Valley at the junction between the African Great Lakes region and Southeast Africa, with a population of over 14 million peop ...

and

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

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

Lake Tanganyika Lake Tanganyika ( ; ) is an African Great Lakes, African Great Lake. It is the world's List of lakes by volume, second-largest freshwater lake by volume and the List of lakes by depth, second deepest, in both cases after Lake Baikal in Siberia. ...

. 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 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 pC, 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 rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

Lakes and rivers

The northern part of the rift is crossed by two large mountain ranges, the

Rwenzori Mountains The Rwenzori (also known as the Ruwenzori, Rwenzururu or Rwenjura) are a range of mountains in eastern equatorial Africa, located on the border between Uganda and the Democratic Republic of the Congo. The highest peak of the Ruwenzori reaches ...

between Lake Albert and Lake Rutanzige (formerly Lake Edward) and the

Virunga Mountains The Virunga Mountains (also known as Mufumbiro) are a chain of volcanoes in East Africa, in the area where Rwanda, the Democratic Republic of the Congo (DRC), and Uganda meet. The mountain range is a branch of the Albertine Rift 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, which ...

. 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 () 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 contains some of the larg ...

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 Semliki River ( French: ''Rivière Semliki'') is a major river, long, in the Democratic Republic of the Congo (DRC) and Uganda in Central and East Africa. It flows north from Lake Edward in Beni Territory, Nord-Kivu, D.R.C avoiding the Rwenzori ...

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 tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...

into the northern end of Lake Albert and exits as the

White Nile The White Nile ( ') is a river in Africa, the minor of the two main tributaries of the Nile, the larger being the Blue Nile. The name "White" comes from the clay sediment carried in the water that changes the water to a pale color. In the stri ...

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, French language, French: ''Rivière Ruzizi''; Dutch language, Dutch: ''Ruzizi Rivier'') is a river, long, that flows from Lake Kivu to Lake Tanganyika in Central Africa, descending from about to about ...

. Lake Tanganyika then drains into the

Congo River The Congo River, formerly also known as the Zaire River, is the second-longest river in Africa, shorter only than the Nile, as well as the third-largest river in the world list of rivers by discharge, by discharge volume, following the Amazon Ri ...

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,

and

Itombwe Mountains The Itombwe Mountains (or Itombwe Massif, Plateau) are a range of mountains in the South Kivu province of the Democratic Republic of the Congo (DRC). They run along the west shore of the northern part of Lake Tanganyika. They contain a vast area ...

. The Ruwenzori mountains have been identified with

Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...

's "Mountains of the Moon". The range covers an area long by wide. This range includes

Mount Stanley Mount Stanley, also known as Mount Ngaliema (, also , ), is a mountain located in the Rwenzori range. With an elevation of 5,109 m (16,763 ft), it is the highest mountain of both the Democratic Republic of the Congo and Uganda, and th ...

Mount Speke Mount Speke lies in the Ruwenzori Mountains National Park in Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the D ...

and

Mount Baker Mount Baker (; ), 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 State in the United States. Mount Baker has the second-most ...

. 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 Bantu languages in the region, ''Kuragira nyamu'' ...

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 ( French: ''Forêts montagnardes du Rift Albertin'') 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 dis ...

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