Geology 5

Front 1

a'a

Back 1

a lava flow with a nubbly surface

Front 2

accretionary lapilli

Back 2

hailstone-like clumps of wet ash that fall from a volcano eruptive cloud

Front 3

active volcano

Back 3

a volcano that has erupted within the past few centuries and will likely erupt again

Front 4

blocky lava

Back 4

lava that is so viscous that it breaks into boulder-like blocks as it moves; adesitic or rhyolitic

Front 5

caldera

Back 5

a large circular depression with steep walls and a fairly flat floor; formed after an eruption as the center of the volcano collapses into the drained magma chamber below

Front 6

columnar jointing

Back 6

a type of fracturing that yields roughly hexagonal columns of basalt; forms when a dike, sill, or lava flow cools

Front 7

effusive eruption

Back 7

an eruption that produces mostly lava not ash

Front 8

fissure

Back 8

a conduit in a magma chamber in the shape of a long crack through which magma rises and erupts at the surface

Front 9

flood basalt

Back 9

vast sheets of basalt that spread from a volcano vent over an extensive surface of land; may form where a rift develops above continental hot spot and where lava is particularity hot and has low vicosity

Front 10

hyaloclastite

Back 10

a rubbly extrusive rock consisting of glassy debris formed in a submarine or sub-ice eruption

Front 11

ignimbrite

Back 11

rock formed when deposits of pyroclastic flows solidify

Front 12

large igneous providence

Back 12

a region in which huge volumes of lava and/or ash erupted over a relatively short interval of geologic time

Front 13

lapilli

Back 13

any pyroclastic particle that is 2 to 64 mm in diameter

Front 14

lava tube

Back 14

an empty space left when a lava tunnel drains

Front 15

pahoehoe

Back 15

a lava flow with a surface texture of smooth, glassy, rope-like ridges

Front 16

pumice lapilli

Back 16

marble-sized chunks of frothy, siliceous igneous rock that fall from a volcanic eruptive cloud

Front 17

pyroclastic debris

Back 17

fragmented material that sprayed out of a volcanoand landed on the ground or sea floor in solid form

Front 18

pyroclastic flow

Back 18

a fast moving avalanche that occurs when hot volcano ash and debris mix with air and flow down the side of a volcano

Front 19

stratovolcano

Back 19

a large, cone-shaped subarial volcano consisting of alternating layers of lava and tephra

Front 20

supervolcano

Back 20

a volcano that erupts a vast amount of volcanic material during a single event

Front 21

tephra

Back 21

unconsolidated accumulations of pyroclastic grains

Front 22

tuff

Back 22

a pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together