- Cinder cones (scoria cones) -

Cinder cones atop Mauna Kea volcano, Hawaii.
(Photo: P. Ong)

Brief explanation:

A cinder cone (or often also called scoria cone) is a steep, conical hill of volcanic fragments that accumulate around and downwind from a vent. The rock fragments, often called cinders or scoria, are glassy and usually contain numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Cinder cones range in size from tens to hundreds of meters tall and are usually formed by lava fountains or strombolian eruptions.
Cinder cones are the most common, and also smallest type of volcano. They can occur as individual volcanoes, or (more often) as parasitic cones generated by flank eruptions on shield volcanoes and stratovolcanoes. Scoria cones are composed almost wholly of ejected basaltic tephra, most commonly of lapilli- and bomb-size fragments.



A new cinder cone was formed by Etna's eruption in July 2001. All photos were taken from approximately the same position and using the same lens. Note the rapid growth of the cone from the 1st to the 2nd and 3rd picture, taken on July 24, July 25 and July 28.

Some interesting facts:

-- Cinder cones usually erupt lava flows, either through a breach on one side of the crater or from a vent located on a flank. Lava rarely issues from the top (except as a fountain) because the loose, non cemented cinders are too weak to support the pressure exerted by molten rock as it rises toward the surface through the central vent.

-- Perhaps the most famous cinder cone, Paricutin, grew out of a corn field in Mexico in 1943 from a new vent. Eruptions continued for 9 years, built the cone to a height of 424 meters, and produced lava flows that covered 25 km2.

-- Geologists have identified nearly 100 cinder cones on the flanks of Mauna Kea, a shield volcano located on the Island of Hawai`i. On Etna volcano in Italy, there are even more than 300 known cinder cones from prehistoric and historic flank eruptions. Even more might have existed, but have over time been buried beneath lava flows.

-- Usually, cinder cones corresponding to flank eruptions of a volcano erupt only once and can be regarded as extinct already shortly after their activity ceases. 

At the "Red Beach" on Santorini a beautiful cross-section of an old cinder cone is exposed.

Cinder cones on the flank of Mauna Kea.

Monti Silvestri cinder cones on Etna (1892 eruption).