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Strangest Volcano on Earth?
Step into the world of writers and photographers as they tell you about the best, worst, and quirkiest places and adventures they encountered in the field.

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Mountain of God

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By Joel K. Bourne, Jr.Photographs by Carsten Peter

In a remote corner of Tanzania stands an astonishing mountain called Ol Doinyo Lengai, where lava fountains harden in midair then shatter like glass.

Read this compelling excerpt, or print the whole story.

Some people like to climb big granite walls, others frozen waterfalls. Photographer Carsten Peter and his climbing partner Chris Heinlein like to climb erupting hornitos, the sharp, extremely steep hollow pinnacles that sometimes form around active vents. "You can't compare it to normal rock," says Peter of a hornito, or spatter cone. "It's very fragile and very unstable. The cone was rumbling and vibrating, but a rock plate was directing the lava in the other direction." His advice: "Don't try this at home."

Though Ol Doinyo Lengai's fresh natrocarbonatite lavas—which erupt at around 1,000 degrees Fahrenheit (500 degrees Celsius)—are roughly half the temperature of more common basalt lavas, the spattering drops of molten rock will still burn through a cotton jumpsuit like a cigarette through nylons. Yet the dramatic mountain in a remote, little-visited corner of Tanzania invites close inspection, especially from volcanologists. The late photographer and renowned volcano chaser Katia Krafft was captivated by what she called the "toy volcano" because its diminutive flows are cool enough to collect with a spoon.

"It's a perfect little laboratory volcano," agrees Barry Dawson of the University of Edinburgh, the first to study the strange lavas, in 1960, for the Tanzania Geological Survey. "The shape and style of the extrusions exactly mimic the flows of basaltic volcanos, except the latter are so much bigger."

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In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

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Unlike other volcanoes, which spew silica-rich basalts, Ol Doinyo Lengai is the only active volcano on Earth that erupts with a carbonatite, a type of igneous rock rich in carbonates such as calcite and dolomite. Usually carbonatites are intruded into other formations and rarely reach Earth's surface as eruptions.

Ol Doinyo Lengai is unusual not only because its volcanic activity brings a carbonatite to the surface, but also because the type of carbonatite is special. Called natrocarbonatite, Ol Doinyo Lengai igneous rock is rich in sodium.

Although in the geologic past there have been other carbonatite volcanoes, it is difficult to tell whether any spewed natrocarbonatite lava. When exposed to moisture, natrocarbonatite quickly transforms in composition and texture and, being extremely water soluble, is easily washed away by rains.

—Mary Jennings

Did You Know?

Related Links
The Ol Doinyo Lengai Website
A comprehensive website that includes photographs and information on past eruptions, brought to you by Ol Doinyo Lengai expert Celia Nyamweru.

Volcanoes of the World
Get statistics from the Smithsonian Institution's Global Volcanism Program.

Ol Doinyo Lengai: The Mountain of God
Here's another informative website, this one from self-described "volcano chaser" and Ol Doinyo Lengai climber Frederick Belton.

Volcano World: Ol Doinyo Lengai
View photographs, read about recent activity, and find more links at this site about volcanoes of the world.

The Maasai Association
Read about history, ritual, and ceremonies, and current issues concerning this traditionally pastoral people.


Bell, K., and J. Keller, eds. "Carbonatite Volcanism: Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites" (a volume of the IAVCEI Proceedings in Volcanology). Springer-Verlag, 1995.

Carr, Rachel, and Solomon ole Saibull. Herd and Spear: The Maasai of East Africa. Collins and Harville Press, 1981.

Francis, Peter. Volcanoes: A Planetary Perspective. Clarendon Press, 1993.

Krafft, Maurice, and Jorg Keller. "Temperature Measurements in Carbonatite Lava Lakes and Flows from Oldoinyo Lengai, Tanzania," Science (July 14, 1989), 168-170.


NGS Resources
Pinna, Marco. "Etna Ignites," National Geographic (February 2002), 68-87.

Skelton, Renee. "Hot Stuff! The Cool Adventures of a Volcano Chaser," National Geographic World (June 2001), 12-17.

Schmidt, Jeremy. "Russia's Frozen Inferno," National Geographic (August 2001), 56-73.

Webster, Donovan. "Inside the Volcano," National Geographic (November 2000), 50-65.

Volcano! National Geographic TV, 1989.

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