7.2 Volcanoes Flashcards
aa (AH-ah)
A basaltic lava flow that breaks up into sharp fragments as the lava advances.
Ash
Silt and sand-sized pyroclastic material that may be carried in the atmosphere hundreds or thousands of kilometers downwind from a volcano.
Block
A large, solid pyroclastic particle ejected from volcanoes.
Bomb
A large, molten pyroclastic mass ejected from volcanoes.
Caldera
A large volcanic crater.
Cinder
A pea-sized pyroclastic particle.
Cinder cone
A small volcano built mainly from loose pyroclastic material such as cinders and lapilli.
Composite cone
A volcano made of alternating layers of lava flows and pyroclastic material.
Crater
A steep-walled depression at the summit of a volcano.
Fissure eruption
A volcanic eruption where lava is erupted from long cracks in Earth’s crust called fissures rather than from craters at the summits of volcanoes.
Lahar
A thick, dense mixture of water and pyroclastic material that flows down the slopes of a volcano.
Lapilli
A walnut-sized pyroclastic particle.
Nuée ardente (noo-EH ar-DAWNT)
A mixture of pyroclastic materials and very hot steam which moves rapidly down the slopes of a volcano with very little friction.
Pahoehoe (pah-HO-ee-ho-ee)
A smooth-surfaced basaltic lava flow.
Pipe
The conduit which connects a volcanic crater to a magma chamber at depth.
