Glossary

Below are some of the most common terms you will encounter while researching volcanoes.  If the word isn't listed on this page, you can locate a definition and image at this website.  Or, if you would like to hear the pronunciation of the word (how to say it), you can find that here.

basalt
dark, volcanic rock or lava

crust
 the solid and outer layer of the Earth

fissure
a crack in the surface

debris avalanche
 loose pieces of rocks and other matter that
rushes down the slope

cinder cone
a conical hill made of volcanic debris
around a vent

lava
molten rock that has reached the surface

pumice
a light, porous volcanic rock that forms
from eruptions

pyroclastic flow
hot ash, pumice, rock fragments, and gases

magma
molten rock material beneath the surface

dormant - a sleeping or inactive volcano that may erupt in the future