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44 terms

Ch 7 Earth Science

Foundation of Earth Science Pearson Hall
STUDY
PLAY
as flow
it flows in a direction and manner dictated by the lay of the land and underlying bedrock
batholith
A mass of rock formed when a large body of magma cools inside the crust
caldera
The large hole at the top of a volcano formed when the roof of a volcano's magma chamber collapses.
cinder cone
a steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening
columnar joint
A regularly spaced crack that commonly develops in lava flows forming five or six sided columns
composite cone
A volcano composed of both lava flows and pyroclastic material.
concordant
A term used to describe intrusive igneous masses that form parallel to the bedding of the surrounding rock
conduit
a passage (a pipe or tunnel) through which water or electric wires can pass
continental volcanic arc
mountains formed by igneous activity associated with the subduction of oceanic lithosphere beneath a continent
crater
a bowl-shaped area that forms around a volcano's central opening
dike
a slab of volcanic rock formed when magma forces itself across rock layers
discordant
not in agreement or harmony
eruption columns
jets of hot ash-laden gases that evolve into bouyant plumes that extend thousands of meters into the atmosphere
fissure
a long narrow depression in a surface
fissure eruption
the eruption of magma out of a crack in the lithosphere, rather than from a single pipe or vent
flood basalt
flow of basaltic lava that issue from numerous cracks or fissures and commonly cover extensive areas to thicknesses of hundreds of meters
fumarole
A volcanic vent emitting only gas and steam
hot spot
an area where magma from deep within the mantle melts through the crust above it
intraplate volcanism
igneous activity that occurs within a tectonic plate away from plate boundaries
intrusions
magma that has pushed into cracks in existing rocks
island arc
A string of islands formed by the volcanoes along a deep ocean trench
laccolith
when magma pushes up the earth's surface and cools forming a dome
lahar
an avalanche of volcanic water and mud down the slopes of a volcano
lava tube
tunnel in hardened lava that acts as a horizontal conduit for lava flowing from a volcanic vent. lava tubes allow fluid lavas to advance great distances
mantle plume
A buoyant mass of hot rock rising through Earth's mantle. As it nears the surface of Earth, some of the plume melts and erupts at the surface forming a "hot spot."
massive
consisting of great mass
nuee ardente
The most dangerous pyroclastic flow, incandescent volcano debris float up and then fall down in avalanche form, can move at 125 miles per hour, suspended by gases
pahoehoe flow
a lava flow with a smooth-to-ropy surface
parasitic cone
a volcanic cone that forms on the flank of a larger volcano
pipe
a long tube through which magma moves from the magma chamber to Earth's surface
pluton
large mass of intrusive igneous rock believed to have solidified deep within the earth
pyroclastic materials
the volcanic rock ejected during an eruption including ash, bombs, and blocks
scoria cone
a rather small volcano built primarily of pyroclastics ejected from a single vent with hardened lava
shield volcano
A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava
sill
(geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock
stocks
...
stratovolcano
A concave-shaped volcano containing alternating layers of lava flows and beds of pyroclasts.
tabular
Describing a feature such as an igneous pluton having two dimensions that are much longer than the third
vent
a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt
viscosity
resistance of a liquid to sheer forces (and hence to flow)
volatiles
gaseous components of magma dissolved in the melt. They will readily vaporize at surface pressures
volcanic island arc
a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another
volcanic neck
solid igneous core of a volcano left behind after the softer cone has been eroded
volcano
a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt