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Cinder cones are the simplest type of volcano. Cinder cones are chiefly formed by Strombolian eruptions. Cinder cones can only occur alone or in small to large groups or fields. The longer the eruption takes place, the higher the cone. If gas pressure drops, the final stage cinder cone construction may be a lava flow that breaks through the base of the cone.
Composites volcanoes are made of layers of lava, ash, cinders, and bombs. Composite volcanoes are tall, evenly shaped, with steep sides, sometimes as high as 10,000 feet. Composite volcanoes comprise the largest percentage (60%) of the Earth’s individual volcanoes. Some composite volcanoes are just a collection of domes piled up on each other.
Shield volcano is made of thin pahoehoe lava from quiet eruptions hardening on layers of lava over and over again. Lava tubes are essential for building broad shield volcanoes, because they can permit lava to travel great distances from an erupting vent. Eruptions at shield volcanoes are only explosive if water somehow gets into the vent.
Volcanic or lava domes are formed by relatively small, bulbous masses of lava too viscous to flow any great distance; consequently, on extrusion, the lava piles over and around its vent. A dome grows largely by expansion from within. As it grows its outer surface cools and hardens, then shatters, spilling loose fragments down its sides.
Summary of Major Points
The four types of volcanoes are the Cinder Cone Volcano, Composite Volcano, Shield Volcano, and Lava Domes.
Cinder cone volcanoes are built from particles and blobs of congealed lava ejected from a single vent.
In a cinder volcano, as the gas-charged lava is blown into the air, it breaks into small pieces that solidify and fall around the vent to form a circular or oval cone.
Composite volcanoes are formed by alternating layers of lava and rock fragments.
The main feature of a composite volcano is a conduit system in which magma from a reservoir deep in the Earth's crust rises to the surface.
Shield volcanoes are built almost entirely of fluid lava flows.
Lava tubes are needed for making a shield volcano because they can let lava travel long distances from an erupting vent.
Lava domes are formed by masses of lava.
As a lava dome grows , its outer surface cools and hardens.