Chapter 9 Vocab - Volcanoes

Question 1

aa flow

Answer 1

a type of lava flow that has a jagged, blocky surface

Question 2

batholith

Answer 2

a large mass of igneous rock that formed when magma was emplaced at depth, crystallize, and subsequently exposed by erosion

Question 3

caldera

Answer 3

a large depression typically caused by collapse or ejection of the summit area of a volcano

Question 4

cinder cone

Answer 4

a rather small volcano built primarily of pyroclastic ejected from a single vent

Question 5

columnar joint

Answer 5

a pattern of cracks that form during cooling of molten rock to generate columns that are generally six sided

Question 6

composite cone

Answer 6

a volcano composed of both lava flows and pyroclastic material

Question 7

conduit

Answer 7

a pipeline opening through which magma moves toward earth’s surface. it terminates at the vent

Question 8

continental volcanic arc

Answer 8

mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent

Question 9

crater

Answer 9

the depression at the summit of a volcano, or that which is produced by a meteorite impact

Question 10

decompression melting

Answer 10

melting that occurs as rock ascends due to a drop in confining pressure

Question 11

dike

Answer 11

a tabular shaped intrusive igneous feature that cuts through the surrounding rock

Question 12

eruption column

Answer 12

buoyant plumes that extend thousands of meters into the atmosphere

Question 13

fissure

Answer 13

an eruption into which lava is extruded from narrow fractures or cracks in the crust

Question 14

flood basalt

Answer 14

flows of basaltic lava that issue from numerous cracks or fissures and commonly cover extensive areas to thicknesses of hundreds of meters

Question 15

fumarole

Answer 15

a vent into a volcanic area from which fumes or gases escape

Question 16

geothermal gradient

Answer 16

natural steam used for power generation

Question 17

hot spot

Answer 17

a concentration of heat into the mantle capable of producing magma, which in turn exudes onto earth’s surface

Question 18

intraplate volcanism

Answer 18

igneous activity that occurs within a tectonic plates away from plate boundaries

Question 19

island arc

Answer 19

a chain of volcanic islands generally located a few hundred kilometers from a trench where active subduction of one oceanic slab beneath another is occurring

Question 20

laccolith

Answer 20

a massive igneous body intruded between preexisting strata

Question 21

lahar

Answer 21

mudflows on the slopes of volcanoes that result when unstable layers of ash and debris become saturated and flow downslope, usually following stream channels

Question 22

lava tube

Answer 22

tunnel hardened lava that acts as a horizontal conduit for lava flowing from a volcanic vent.

Question 23

mantle plume

Answer 23

a mass of hotter than normal mantle material that ascends toward the surface, where it may lead to igneous activity

Question 24

nuee ardente

Answer 24

incandescent volcanic debris buoyed up by hot gases that moves downslope in an avalanche fashion

Question 25

pahoehoe flow

Answer 25

a lava flow with a smooth to ropey surface

Question 26

parasitic cone

Answer 26

a volcanic cone that forms on the flank of a larger volcano

Question 27

partial melting

Answer 27

the process by which most igneous rock melts

Question 28

pipe

Answer 28

a vertical conduit through which magnetic materials have passed

Question 29

pluton

Answer 29

a structure that results from the emplacement and crystallization of magma beneath the surface of earth

Question 30

pyroclastic flow

Answer 30

a highly heated mixture, largely of ash and pumice fragments, traveling down the flanks of a volcano or along the surface of the ground

Question 31

pyroclastic materials

Answer 31

the volcanic rock ejected during an eruption, including ash, bombs, and blocks

Question 32

scoria cone

Answer 32

a rather small volcano built primarily of pyroclastic ejected from a single vent

Question 33

shield volcano

Answer 33

a broad, gently sloping volcano built from fluid basaltic lavas

Question 34

sill

Answer 34

a tabular igneous body that was intruded parallel to the layering of preexisting rock

Question 35

stratovolcanoes

Answer 35

a volcano composed of both lava flows and pyroclastic material

Question 36

vent

Answer 36

surface opening

Question 37

viscosity

Answer 37

a measure of a fluid’s resistance to flow

Question 38

volatiles

Answer 38

gaseous components of magma dissolved in the melt

Question 39

volcanic island arc

Answer 39

a chain of volcanic islands generally located a few hundred kilometers from a trench where active subduction of one oceanic slab beneath another is occurring

Question 40

volcanic neck

Answer 40

an isolated, steep sided, erosional remnant consisting of lava that once occupied the vent of a volcano

Question 41

volcano

Answer 41

a mountain formed of lava and/or pyroclastic