Scoria cone

Scoria cones, also known as cinder cones, are the most common type of volcano. They are also the smallest type, with heights generally less than 300 meters. They can occur as discrete volcanoes on basaltic lava fields, or as parasitic cones generated by flank eruptions on shield volcanoes and stratovolcanoes. Scoria cones are composed almost wholly of ejected basaltic tephra. The tephra is most commonly of lapilli size, although bomb-size fragments and lava spatter may also be present. The tephra fragments typically contain abundant gas bubbles (vesicles), giving the lapilli and bombs a cindery (or scoriaceous) appearance. The tephra accumulates as scoria-fall deposits which build up around the vent to form the volcanic edifice. The edifice has very steep slopes, up to 35 degrees. Unlike the other two main volcano types, scoria cones have straight sides and very large summit craters, with respect to their relatively small edifices. They are often symmetric, although many are asymmetric due to (1) the build up of tephra on the downwind flank of the edifice, (2) elongation of the volcano above an eruptive fissure, or (3) partial rafting of an outer wall of the volcano due to basalt lava oozing outward from beneath the volcano edifice. Where scoria cones have been breached, they typically reveal red-oxidized interiors.

Scoria cones are generated by strombolian or hawaiian eruptions. Many scoria cones are monogenetic in that they only erupt once.

 

This photo, taken in april 2001, shws a parasitic cone (called Château Fort) on the Flank of Piton de la Fournaise

 

 

 

 

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