Geology 1121- Ch 5 Quiz

Aa Lava

chunky lava that is usually full of vesicles

Andesitic lava

intermediate composition lava that may plug volcanoes

Basaltic lava

mafic composition lava that is runny

Columnar Joints

fracturing during cooling that makes hexagonal colums

Pahoehoe

ropy lava

Pillow lava

piles of ellipsoidal basalt that form underwater

Rhyolitic

highest viscosity lava that is likely to plug volcanoes

Ash

what term best describes fine-grained pyroclastic material?

Pyroclastic Flow

hot ash and gas that flows downhill at high speeds

Central Vent

primary eruption site at the center of a symmetrical volcanoe

fissure eruption

magma that is fed through large, nearly vertical cracks in earths surface

large igneous province

What is a synonym for flood basalt?

Shield Volcano

broad, pancake shape volcano, basaltic lava flows

Stratovolcano

cone-shaped, lava and pyroclastic (steep, small central vent)

Cinder cone

cone-shaped, pyroclastic debris (steep, large central vent)

Caldera

big circular depression, lots of magma discouraged rapidly

flood basalts

immense plateau of basalt, form from fissure eruptions

ocean-ocean convergence

island arc, Aleutian Islands