Chapter 9
Volcanoes
Vocabulary:
Aa: A solidified basaltic lava flow on land that has formed with rough,
jagged surfaces.
Caldera: base level. The level of the body of water into
Cinder Cone: A cone-shaped volcano formed from lava fragments that have
been ejected from a volcanic vent.
Composite Volcano: A volcano made of layers of hardened lava flows and
pryoclastic materials
Hot Spot: An area of volcanic activity that results from a plume of hot solid
material that has risen from deep within Earth’s mantle.
Lahar: a fast-moving mudflow that occurs when the heat associated with a
volcanic eruption melts snow and ice on top of a volcano.
Lava: Magma that reaches Earth’s surface.
Lava Plateau: A plateau formed from basaltic lava pouring from a crack or
fissure in Earth’s surface.
Pahoehoe: Solidified basaltic lava flow on land that has formed with smooth,
ropelike surfaces.
Pillow Lava: Lava that cools underwater, taking on a distinctive pillow-like
shape as it hardens.
Pyroclastic Flow: A dense, superheated cloud of gases and pyroclastic
material that moves rapidly downhill from an erupting volcano.
Pyroclastic material: Solid rock fragments that are ejected during a volcanic
eruption.
Shield Volcano: A shield-shaped volcano with a broad base and gently
sloping sides that is made of basaltic lava.
Viscosity: A substance’s resistance to flow.
Volcano: An opening in Earth’s crust through that molten rock, gases, and
ash erupt; also, the landform that develops around this opening.