Volcano Exam
decompression melting
oceanic ridges melting at hotspots
Pillow Lava
forms when lava erupts underwater
Pyroclastic
fragmental texture, broken up rock
vesicle
gas bubble in rock
Volcanic gases
gases emitted include water vapor, carbon dioxide, and sulfur gases.
Dike
narrow igneous intrusion that cuts through rock
Atoll
a ring-shaped reef, island, or chain of islands formed of coral.
sulfur dioxide
a colorless pungent toxic gas formed by burning sulfur in air.
texture
feel & arrangement of minerals in rock
Aphanitic
fine grained
Cinders
a fragment of ash
Scoria
a glassy, mafic, igneous rock containing abundant air-filled holes
fine
very small grains
Shield Volcano
very wide ranging many KM
Batholith
100 km or more - a very large igneous intrusion extending deep in the earth's crust.
Stock
100 km less - Igneous intrusion
Basalt
A dark, dense, igneous rock with a fine texture, found in oceanic crust
Rhyolite
A light-brown to gray, fine-grained extrusive igneous rock with a felsic composition. The extrusive equivalent of granite.
minerals
A natural substance that is typically solid, has a crystalline structure, and is typically formed by inorganic processes. Minerals are the building blocks of most rocks.
Composite Volcano
A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials
Andesite
An intermediate colored rock, generally gray greenish-gray, also classed as an aphanite because of the small crystal or grain size.
Assimilation
Bedrock around the magma chamber going into magma, changing the composition
carbon dioxide
CO2
volcanic tremor
Ground motion lasting from minutes to hours, resulting from magma moving beneath the surface, as opposed to the sudden jolts produced by most earthquakes.
Seismometer
Instrument used to measure horizontal or vertical motion during an earthquake.
Lava
Liquid rock on the surface of Earth
Magma
Liquid rock within the Earth
Pahoehoe Lava
Low silica, Low viscosity, low rate of lava infusion
Tiltmeter
Measures changes in a volcano's slope
Glassy
Only glass, no minerals (no cooling, quenching)
Volcano
Place where lava is erupted at the surface
Aa Lava
Rough surface, higher lava infusion, breaking glasses
Ash Fall
The deposition of a layer of fine airborne rock and glass that have been erupted from a volcano
pyroclastic flow
The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption
Cinder Cone Volcano
Volcanoes found on composites and formed by a single eruption
Pluton
a body of intrusive igneous rock.
Tsunami
a long high sea wave caused by an earthquake, submarine landslide, or other disturbance.
Columnar Joint
a pattern of cracks that form during cooling of molten rock to generate columns that are generally six sided
GPS (global positioning system)
a system that accurately determines the precise position of something on Earth
Sill
a type of dike parallel to bedding planes
Flux Melting
main source of magma for island and volcanic arcs in convergent boundaries
Porphyritic
both large and small grains
vesicular
bubbly
Phaneritic
coarse grained, large crystals
Mafic
dark colored, low silica
heat induced melting
heat from magma melting crust
Tuff
igneous rock when minerals cement together
correlation spectrometer
instrument used to measure volcanic gases
Felsic
light colored, high silica
Volcanic
materials relating to a volcano; rock, range, characterized
Volatiles
materials that turn into gas at the surface
Groundmass
matrix of smaller crystals
Igneous
rocks that are formed from liquid rock
coarse
rough, seen with naked eye
Lapilli
tephra that is between 2 mm and 64 mm
Ash
tephra that is less than 2 mm in diameter
Phenocryst
the large grains in a porphyritic rock
partial melting
the process by which different minerals in rock melt at different temperatures
partial crystallization
turns rock more felsic, magma cools and crystalizes
Xenolith
unmelted country rocks within igneous rock mass
Ultramafic
very dark, extremely low silica
Lahar
volcanic mudflow
Pumice
volcanic rock with high content of water and gases
water vapor
water in the form of a gas
