Mount OlDoinyo Lengai:
“Oldoinyo Lengai” means “The Mountain of God” in Maasai. The summit of this stratovolcano is 2962 meters above sea level and provides direct views into the caldera of Tanzania’s only officially certified active volcano and the world’s only carbonatite volcano; records of eruptions have been kept since 1883, with the largest depositing ash 100 kilometres away in Loliondo on the Kenyan border to the northwest. Ol Doinyo Lengai is unique among active volcanoes in that it produces natrocarbonatite lava, a rare type of volcanic carbonatite. There are a couple older extinct carbonatite volcanoes nearby, including Homa Mountain.
Most lavas contain silicate minerals, however Ol Doinyo Lengai’s lava is carbonatite. It contains the rare sodium and potassium carbonates, nyerereite and gregoryite. Due to its peculiar composition, the lava erupts at comparatively moderate temperatures of around 510 °C. Because of the low temperature, the molten lava appears black in sunlight rather than the red glow that typical lavas have. It is also far more fluid than silicate lavas, and frequently less viscous than water. The sodium and potassium carbonate minerals in the lavas that erupted at Ol Doinyo Lengai are unstable at the Earth’s surface and subject to rapid weathering, turning black to grey in colour. The ensuing volcanic landscape is unlike any other in the globe.
Carbonatite ash strewn across the neighbouring grasslands results in a succulent, enhanced pasture. As a result, the area plays an important role in the yearly wildebeest migration, serving as a nursery for the birth of thousands of calves.
It is located in northern Tanzania, just south of Lake Natron in the Rift Valley, in the heart of Maasai territory, and is revered as a sacred mountain. Looking north from the summit crater, the hot, barren salt flats of Lake Natron extend into the distance. To the south lie the Crater Highlands and the Ngorongoro Game Reserve. Kilimanjaro dominates the eastern horizon, while the western slopes of the Rift Valley are covered in forested escarpments and hills. Every seven years, Lengai erupts and emits plumes of smoke from its crater.
The lava flowing from Ol Doinyo Lengai is unusually cool: at “only” up to 950 degrees Fahrenheit, it is about twice as cold as silicate magma.
In the sunshine, this comparatively mild temperature causes the lava to appear black and grey rather than the traditional red. When the lava hardens, it forms a distinct hue of white. And because lava can cool and harden in seconds once it comes into contact with this atmosphere, it occasionally shatters in mid-air and rains down the slopes.
It is feasible to stroll across the crater floor. The ascent of Oldoinyo Lengai is difficult due to the daytime heat, lack of water, steep and unsuitable slopes of ash and crumbly rocks, and significant height increase. Normally, you can begin ascending to the summit early in the morning and reach it about sunrise. Shorts and a warm jacket are appropriate for ascent, and long trousers are recommended because the top before dawn can be cold. The access path from the northwest provides for an early descent from the top in the morning shadow.
Mountain Ol’doinyo Lengai, also known as the Mountain of GOD to the Maasai population that live in the area, is 2,878 meters above the Soda Ash Lake Natron. It is located in the Ngorongoro highlands and the African Rift Valley, approximately 120 km northwest of Arusha, Tanzania.
Maasai have employed the Holly Lengai for prayer to their GOD, known as NGAI, since their forefathers’ time. Ol’doinyo Lengai is the world’s only active volcano that erupts natrocarbonatite lava, which is colder than other lavas (510 degrees Celsius) compared to the temperatures of basaltic lavas (1,100 degrees Celsius) containing less silicon.
Minor eruptions occur often on the mountain, and cone-like structures emerge at the crater’s base.
While on the summit of Mountain Ol’doinyo Lengai, one can clearly see the Soda Lake Natron, which accommodates and contains suitable nesting grounds for various bird species, particularly flamingos, pelicans, and geese; over 350 distinct types have been reported to far.
Unlike the other two highest mountains, Lengai takes approximately six to seven hours to reach the top crater. Also, the Mountain is a perfect location for a working safari escorted by Maasai escorts armed with guns, where tourists can see wild species such as olive baboons, velvet, monitor lizards, hyenas, lions, leopards, jackals, Grant’s gazelle, impalas, and zebras.
Nearby are the Maasai BOMAS, which allow you to connect with the indigenous and learn about their cultures, taboos, and traditions.
Now, if you understand volcano behaviour, you’ll know that a low viscosity magma is unlikely to erupt explosively. That’s because gas bubbles can escape from the lava without becoming trapped, resulting in fragmentation. So, you’d expect Ol Doinyo Lengai to erupt only when lava flows with such low viscosity lava. However, the volcano has produced both explosive and effusive eruptions in the last decade, which is most likely related to the amount of carbon dioxide that can be dissolved in the magma. The more carbon dioxide (or any other gas) you can pack into the lava, the more probable it will erupt explosively, regardless of its viscosity. Ol Doinyo Lengai had a remarkable explosive eruption in 2008 (see below), resulting in an ash plume, and carbonatite ash falls and tephra have been discovered throughout its recent history. The video of the eruption (above) shows that some of the lava appears silvery, indicating the presence of a huge number of bubbles even during these relatively inactive eruptions.
Aside from the distinct temperature and colour, Ol Doinyo Lengai’s lava is also recognised for being the least viscous and most “runny” in the globe. The lava is not just emitted from the main crater; little peaks on the volcano’s surface known as “hornitos” also spew the bizarre substance.
For all of these reasons, scientists prefer the volcano because it is easier to study than its dangerously hot counterparts—it is even referred to as a “toy volcano.” It’s so safe that a hiker apparently plunged into the volcano and survived, despite being severely burned.
Typically, the volcano’s activity is limited to the summit. However, the Mountain of God can occasionally erupt in a more dramatic manner: on September 4, 2007, the volcano emitted an ash plume that extended at least 11 kilometres downstream. Lava flowing down the north and west flanks created burn scars that could be seen from space.
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