Volcano Types and Characteristics Flashcards
What is extrusive rock?
Igneous rock formed by the crystallisation of magma above the surface of the Earth.
What is intrusive rock?
Igneous rock formed by the crystallisation of magma below the surface of the Earth.
Basaltic lava is found where?
At spreading ridges and hot spots.
Andesitic and Rhyolitic lavas are found at…
destructive and collision plate boundaries
Ryholitic lavas can be located at…
destructive and collision margins
As the silica content increases what happens to the lava?
It gets more viscous (thicker)
From Basaltic to Ryholitic
What are the volcano classifications?
- Fissure
- Shield
- Composite
- Acid/Dome
- Caldera
Minor extrusives include…
- Geysers and hot springs
- Solfataras
- Fumaroles
- Boiling Mud volcanoes
A fissure is..
an elongated crack in the crust allowing basaltic lava to spill out on to a large area.
they re found at spreading ridges, where the crust is pulled apart.
An example of a fissure eruption is the…
Heimaey, Iceland in 1973
Evidence of fissures can be seen in…
Rock fragments in the columnar basalts of the Giants Causeway in Northern Ireland
And Fingal’s Cave on the Isle of Staffa, Scotland.
Shield volcanoes are…
produced from basaltic rock and form gentle sloping cones of less viscous lava.
An example of a shield volcano is…
the Mauna Loa in Hawaii
largest in the world as it stands 4,169 above sea level and the structure extends 10,099 from the ocean floor.
Composite volcanoes are the…
most common type of volcano
created by layers of ash and lava
Examples of composite volcanoes include…
Mount Etna, Sicily, Italy
Mount Vesuvius
Acid or Dome volcanoes are…
steep sided volcanoes formed from very viscous lava (Rhyolitic lava), as it cannot travel far
builds up convex cone shaped volcanoes
lava can solidify in vent and revealed later by erosion.
An example of a dome volcano feature is the…
Puy de Domes in France
Calderas form when…
gases that have built up beneath blocked volcanic vents eventually result in a catastrophic eruption.
the caldera eruption…
destroys the volcano summit and leaves an enormous crater.
later eruption may form smaller cones.
A geyser is…
an intermittent turbulent discharge of superheated water ejected on the surface.
Geysers form when…
water in the lower crust is heated by magma chambers and turns to steam and explodes on the surface.
Solfataras fare created when….
steam mixes with sulphur-rich gases and escape onto the surface
Mud volcanoes form when…
rising hot water mixes with mud on the surface
Fumaroles form when…
superheated water turns to steam as its pressure drops when it emerges on the ground.
