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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.