Volcanoes Flashcards
Products escape thru a single pipe or vent
Central type
Ejection of lava takes place from a long fissure or a group of parallel or closed fissures
Fissure type
Lava is of acidic(Felsic) in nature and because of their high degree of viscosity
Explosive Eruption
Lava is of basaltic(Mafic) which is highly fluid and holds little gas and lava can travel long distances to spread out in thin layers
Quiet eruption
Silent effusion of lava without any explosive activity
Hawaiian Type
Periodic eruption, with a little explosive activity
Strombolian Type
Eruption takes place at longer intervals and the viscous lava quickly solidifies and gives rise to explosions of volcanic ash
Vulcanian Type
Highly explosive volcanic activity and eruption occurs after a long interval (measured in tens of years)
Vesuvian Type
The most violent type of vesuvian eruption. Huge fragment of fragmental products are given out with little or no discharge of lava
Plinian Type
Most violent type of all the eruptions. Characterized by eruption of nuees ardentes
Pelean Type
Very small lava flows
Hornitos
Most acid lavas often give rise to quite small conelets
Driblet Cones
Volcanoes of central types, steep sided with uniform slopes of 30 40 degrees
Cinder cones
Built up of lava flows due to heaping of lava during quiet type of explosion. Also known as plug dome
Lava cone
Made up of alternatively of pyroclastic material and lava. Due to rude stratification, they are also known as stratovolcanoes.
Composite cones
Made up of lava alone and due to quiet type of explosions whereby piling up of flow after flow of fluid lava, a rounded like mass is produced
Shield Volcanoes
Small cones formed on lava flows where breaks occur in the cooled surface of the flow allowing hot gases and lava to be blown out
Spatter cones
Formed because of fissure type of eruptions
Volcanic Plateau
Depression located at the summit of the volcanic cone
Crater
Due to erosion and enlargement of the crater
Calderas
More mobile lavas of basic composition, when erupted on the surface in the form of flows quickly consolidate and form a solid crust while the interior may still remain fluid.
Lava tunnels
After an explosion destroys an exiting crater, a new built smaller cone with its own crater is built up
Cone in cone topography
Pyroclastic material with a diameter which is always above 32mm
Volcanic blocks or bombs
Pyroclastic material with a diameter between 4mm to 32mm
Lapilli or cinders
Pyroclastic material with a diameter ranging between 0.25mm to 4mm
Ash
Pyroclastic material with minute particles of diameter less than 0.25 mm
Fine Ash
Rocks made up of ash and fine ash
Tuff
Welded tuffs are known as _____?
Ignimbrite
Pyroclastic rocks consisting mainly of fragments larger than 20mm in diameter
Agglomerates
These are albitic lava and it produces pillow structures
Spilitic Lava
An incandescent cloud of gas and volcanic ash
Nuee Ardente
Fissures or vents thru which volcanic gases are ejected
Fumaroles
Fumaroles emitting sulphurous vapors
Solfataras
Fumaroles emitting boric acid
Saffoni
Fumaroles emitting carbon dioxide
Mofettes
Fissures thru which hot water escapes
Hot springs
Calcareous deposits formed from hot springs
Travertine or tufa
Similarly siliceous deposits are known as _____?
Siliceous sinters
Hot spring ejecting boiling water and steam at regular intervals
Geysers
Siliceous deposits formed around geysers
Geyserites
Examples of pseudo-volcanic features
mud volcanoes and meteor craters
