Chapter 4 Volcanoes

caldera A large circular depression, or basin, at the top of a volcano

cinder cone volcano a kind of volcano, usually small and steep-sloped, that is formed from layers of cinders which are sticky bits of volcanic material

composite cone volcano A kind of volcano formed when explosive eruptions of sticky lava alternate with quieter eruptions of volcanic rock bits

hot spot A place deep within Earth’s mantle that is extremely hot and contains a chamber of magma

island arc A chain of volcanoes formed from magma that rises as a result of an oceanic plate sinking into the mantle

lava Magma that flows out onto Earth’s surface from a volcano

magma The hot molten rock deep inside the earth

rifting The process by which magma rises to fill the gap between two plates that are moving apart

seismometer An instrument that detects and records Earth’s movements

shield volcano A kind of volcano that is large and gently sloped and that is formed when lava flows quietly from a crack in the earth’s crust

volcano An opening in Earth’s crust through which hot gasses, rock fragments and molten rock erupt