49 Fun Facts About Great Rift Valley

In its original definition, the Great Rift Valley runs from northern Syria to which African country?

Mozambique: the rift has been tearing open for millions of years, and the volcanic activity along it built Kilimanjaro and Mount Kenya, Africa's two highest mountains.

Which British geologist introduced the term Great Rift Valley in 1896?

John Walter Gregory coined it as the title of his 1896 book about a journey to Mount Kenya and Lake Baringo. Still exploring at 68, he drowned when his canoe overturned on a river in Peru.

A rift valley is a long, steep-sided valley that has done what?

Dropped between a series of faults: as the crust is stretched, a block of land sinks between parallel fractures, so the valley is made by collapse from below rather than carved from above by water or ice.

The East African Rift is slowly splitting the African plate into which two plates?

Somali and Nubian: as the two plates part, the small Victoria plate caught between them is being turned anticlockwise, the opposite way to its neighbours.

If the East African Rift keeps widening, what is expected to form between its two sides?

A new ocean: the sides part by only a few millimetres a year, so the sea is millions of years away, yet in Ethiopia's Danakil Depression the rift floor already lies below sea level.

Rift Valley fever, first identified among sheep in Kenya in 1931, spreads between animals mainly through the bite of what?

Mosquitoes carry the virus, so outbreaks follow unusually heavy rains and floods, when huge numbers hatch; people usually catch it from the blood or raw milk of infected animals.

Where do the Red Sea Rift, the Aden Ridge and the East African Rift meet?

The Afar triple junction is still tearing open: in September 2005 a 60 km stretch of the Afar rift was wrenched apart by as much as 8 metres as molten rock forced its way in.

Lake Albert, in the rift's western branch, was named in 1864 for which royal?

Britain's Prince Albert had died in 1861, and explorer Samuel Baker, reaching the lake in 1864 while searching for the Nile's headwaters, named it for Queen Victoria's late consort.

The Dead Sea Transform, the fault behind the rift's Asian section, separates the African plate from which other plate?

The Arabian plate is sliding north past Africa along this fault and has shifted about 105 km so far; a basin pulled open along the way now holds the Dead Sea.

Which river flows south along the rift valley floor and empties into the Dead Sea?

The Jordan ends in the Dead Sea, which has no outlet; so much of the river is now diverted for farms and cities that the sea's surface has been falling by about a metre a year.

The shores of the Dead Sea hold which world record?

Lowest land on Earth: the shore lies more than 400 metres below sea level and keeps dropping as the water retreats, which has opened sinkholes along the coast.

The Dead Sea is roughly how many times saltier than the ocean?

About 10 times: the brine is so dense that bathers float without trying, and fish swept in by floods die quickly.

The Virunga volcanoes of the rift's western branch are the best-known home of which endangered great apes?

Gorillas: Dian Fossey studied mountain gorillas from a camp between two of the Virunga volcanoes, and after decades of protection they had recovered to just over 1,000 by 2019.

The Arabah, the dry section of the rift south of the Dead Sea, ends at which gulf?

Aqaba: its gulf is the rift carried on under water, which is why it plunges more than 1,500 metres while the wider Gulf of Suez next door is under 100 metres deep.

For centuries, caravans have carried which commodity out of Ethiopia's Danakil Depression?

Salt: bars cut from the depression's salt flats were carried up to the highlands and served as money across Ethiopia into the 20th century.

Dallol in the Danakil Depression holds what climatic record?

Hottest year-round average temperature: about 35 °C, measured from 1960 to 1966 while a mining company prospected there; Dallol has since emptied into a ghost town.

Erta Ale, a volcano in northern Ethiopia, has held what rare feature at its summit for decades?

A lava lake: molten rock has churned in Erta Ale's summit pit since at least 1967, and possibly since 1906, at times rising high enough to spill over the rim.

The unique soda-rich lava of Tanzania's Ol Doinyo Lengai erupts black, then weathers to which colour?

White: the lava is natrocarbonatite, which no other active volcano erupts, and it is the coolest lava known, so by day it looks more like flowing mud than molten rock.

What do the Maasai call Ol Doinyo Lengai?

The Mountain of God: the Maasai hold it to be the home of their god Engai, and when it erupted in 2007 and 2008 its ash emptied whole villages of the herders living around it.

Kilimanjaro is Africa's highest peak and also the world's highest what?

Free-standing mountain: Kilimanjaro is a lone pile of three volcanoes rather than a peak in a range, so it rises nearly 4,900 metres straight from the plains around it.

Which Kenyan town on the rift's edge calls itself the Home of Champions for its distance runners?

Iten: Colm O'Connell, an Irish missionary who came in 1976 to teach geography, started coaching his pupils with no athletics experience and went on to train a string of world and Olympic champions.

Which lake in the rift's western branch is the world's longest freshwater lake and its second deepest?

Tanganyika was first reached by Europeans in 1858, when Burton and Speke arrived hunting for the headwaters of the Nile, which Speke went on to find later that year at Lake Victoria.

Lake Malawi holds more species of fish than any other lake, most of them from which family?

Cichlids: hundreds of kinds evolved inside this one lake, nearly all of them found nowhere else, and their bright colours have made them favourites of aquarium keepers.

Lake Victoria, though not in a rift trough itself, is Africa's largest lake and the world's largest lake of what kind?

Tropical: Lake Victoria is the largest lake in the tropics yet only about 80 metres deep, because it fills a shallow sag between the rift's two branches rather than a rift trench.

Which invasive fish has driven many of Lake Victoria's endemic species to extinction?

Nile perch were released into the lake in the 1950s; the predators, which can grow to nearly two metres, ate through the native fish until several hundred species had died out or nearly so.

Which desert lake in northern Kenya is nicknamed the Jade Sea for the colour of its water?

Lake Turkana has no outlet, so the water its rivers pour in can leave only by evaporation, which is why so large a lake is brackish.

The Jade Sea's colonial-era name, Lake Rudolf, honoured the crown prince of which empire?

Austria-Hungary: Count Sámuel Teleki named the lake in 1888 for Crown Prince Rudolf, who died at his Mayerling hunting lodge the following year; Kenya dropped the colonial name in 1975.

Lake Natron's water can reach a pH above 12 and does what to the bodies of animals that die in it?

Calcifies them: minerals in the caustic water crust the carcasses as they dry, leaving drowned birds looking like stone statues, which photographer Nick Brandt collected and posed for a famous series.

Lake Natron is the only regular East African breeding site for which birds?

Lesser flamingos nest far out on the lake's soda flats because the caustic water around them keeps predators away, which leaves East Africa's whole flock relying on this one lake.

Lake Kivu, like Cameroon's Lake Nyos, holds enough dissolved gas to suffer which rare catastrophe?

Limnic eruptions: gas held in the deep water can burst out all at once, and the carbon dioxide cloud that Lake Nyos released in 1986 suffocated about 1,700 people.

Olduvai Gorge cuts into the eastern edge of which wildlife region?

Serengeti: erosion cutting down through its eastern plain laid bare stacked beds spanning about two million years, the most continuous record of human evolution known.

At Laetoli, south of Olduvai Gorge, Mary Leakey's team uncovered what, preserved in volcanic ash over 3.5 million years old?

Footprints: early humans crossed a bed of fresh volcanic ash, rain set it like cement, and the trail showed that our ancestors walked upright long before their brains grew large.

The Hadza of Lake Eyasi, on Tanzania's rift floor, are known for which traditional way of life?

Hunter-gathering: many Hadza still live by foraging rather than farming, and their honey-hunters follow a wild bird, the honeyguide, that leads them to bees' nests.

Which Congolese city on the shore of Lake Kivu was overrun by lava from Mount Nyiragongo in 2002?

Goma: lava poured from cracks low on the volcano's flank, ran through the city and over part of the airport runway into the lake, and left more than 100,000 people homeless.

Lake Assal, the lowest point in Africa, lies in which country on the Horn of Africa?

Djibouti: Lake Assal lies 155 metres below sea level and has no outlet, so evaporation under the desert sun has left it far brinier than the ocean.

The fossil skeleton found in Ethiopia in 1974 was nicknamed after which Beatles song?

Lucy in the Sky with Diamonds played over and over in camp on the night of the find, so the team called the skeleton Lucy; in Ethiopia she is Dinkinesh, 'you are marvellous'.

Tanzania's Ngorongoro Crater was formed about 2.5 million years ago when what happened?

A giant volcano collapsed: after a huge eruption the cone fell in on itself, leaving a bowl about 600 metres deep whose grassy floor now shelters lions, elephants and black rhinos.

Which Scottish explorer, remembered in the name of a gazelle, crossed Maasai country in the 1880s and travelled the Kenyan rift?

Joseph Thomson was a geologist in his early twenties on his first African expedition when its leader died, and he took command and led the party on through country unknown to Europeans.

The Red Sea, which links the rift's Asian and African sections, opens into the Gulf of Aden through which strait?

The Bab-el-Mandeb is a gap only about 30 km wide, and once the Suez Canal opened, every ship taking that short cut between the Mediterranean and Asia had to thread it.

Which ancient city on the rift floor just north of the Dead Sea has been settled since about 9000 BC?

Jericho: by about 8000 BC its people had ringed the settlement with a massive stone wall and a tower, thousands of years before the Bible's story of its walls falling.

Which snow-capped range beside the rift's western branch is often identified with Ptolemy's 'Mountains of the Moon'?

The Rwenzori Mountains are not volcanoes, unlike most of Africa's snow peaks: they are a block of crust pushed up beside the rift, high enough to carry glaciers.

Outside Africa, which lake fills another great continental rift and holds about a fifth of Earth's unfrozen fresh water?

Lake Baikal sits in a rift that is still pulling apart, which has made it the deepest lake on Earth, at more than 1,600 metres, and at over 20 million years the oldest.

Which feature on Mars is believed to be a giant rift system 4,000 km long?

Valles Marineris is thought to have cracked open along faults as the crust swelled under the Tharsis volcanic bulge to its west, and erosion then widened it into Mars's largest canyon system.

Which Kenyan rift lake, ringed by a national park, shares a UNESCO World Heritage listing with lakes Elementaita and Bogoria?

Nakuru's national park was fenced to make a sanctuary for two species of rhino, which now graze beside the shallow soda lake and its huge flocks of waterbirds.

Which Lebanese valley, known for vineyards and the Roman temples of Baalbek, is counted as the rift's northern continuation?

The Beqaa Valley is the same trough carried north between two mountain ranges, and it sheds its water both ways: one river rises there and runs north into Syria, another south to the sea near Tyre.

The Jade Sea's island national parks are a major breeding ground for which reptile?

Nile crocodiles breed on the volcanic islands of a lake that once drained into the Nile and has been cut off from it since.

Rwanda's KivuWatt plant generates electricity from which gas, piped up from the depths of Lake Kivu?

Methane: a floating platform pumps up deep water and strips out the gas, which is piped ashore and burned for power, tapping the same store of dissolved gas that makes the lake dangerous.

Which early human species did Louis Leakey's team name in 1964, crediting it with Olduvai Gorge's stone tools?

Homo habilis means 'handy man', a name chosen because it was thought to be the first toolmaker; stone tools older than any fossil of the human genus have since turned up.

Lake Bogoria, a soda lake on Kenya's rift floor, is ringed by hot springs and at least ten what?

Geysers: they spout almost at the waterline, so a rise in the lake drowns some of them and a fall sets others erupting again.