Glossary beginning with C

Volcano Term Definitions


The Spanish word for cauldron, a basin-shaped volcanic depression; by definition, at least a mile in diameter. Such large depressions are typically formed by the subsidence of volcanoes. Crater Lake occupies the best-known caldera in the Cascades.

Capping Stage

Refers to a stage in the evolution of a typical Hawaiian volcano during which alkalic, basalt, and related rocks build a steeply, sloping cap on the main shield of the volcano.

Central Volcano

A volcano constructed by the ejection of debris and lava flows from a central point, forming a more or less symmetrical volcano.

Cinder Cone

A volcanic cone built entirely of loose fragmented material (pyroclastics.)


A steep-walled horseshoe-shaped recess high on a mountain that is formed by glacial erosion.


The breaking of a mineral along crystallographic planes, that reflects a crystal structure.

Composite Volcano

A steep volcanic cone built by both lava flows and pyroclastic eruptions.

Compound Volcano

A volcano that consists of a complex of two or more vents, or a volcano that has an associated volcanic dome, either in its crater or on its flanks. Examples are Vesuvius and Mont Pelee.


A passage followed by magma in a volcano.


A steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent.

Curtain of Fire

A row of coalescing lava fountains along a fissure; a typical feature of a Hawaiian-type eruption