Geological Glossary

Glossary of common terms used in geology, and related to earth sciences.

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Cinder Cone

A colorful cinder cone dominates the skyline at Sunset Crater Volcano National Monument. Cinder cones are cone-shaped volcanic hills made of loose cinders and other tephra. Unlike the violently explosive eruptions that create large stratovolcanoes, cinder cones form when runny (low viscosity) lava with lots of gas erupts as liquid fountains. Lava may be spewed hundreds of feet through the air. The molten rock solidifies instantly, often preserving bubbles created by escaping gasses.

Pu`u `O`o cinder cone erupting in Hawaii. Photograph by J.D. Griggs on September 6, 1983. If an eruption of this type continues long enough, fragments accumulate layer by layer to form a cinder cone. Cinder cones can grow up to 700 meters (2,300 feet) high, but most are between 30 and 300 meters (100 and 1,000 ft).

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