Three Types of Three Types of VolcanoesVolcanoes

Shield VolcanoesShield Volcanoes

Low silica levelLow silica level Low viscosity Lava-thinnerLow viscosity Lava-thinner High or low levels of gasHigh or low levels of gas Flattened moundFlattened mound Resembles a warrior’s shieldResembles a warrior’s shield

Mauna Loa, HawaiiMauna Loa, Hawaii

Piton de la FournaisePiton de la Fournaise

Surtsey, FinlandSurtsey, Finland

Composite VolcanoesComposite Volcanoes

High in silicaHigh in silica High viscosity magmaHigh viscosity magma High levels of gasHigh levels of gas Highly explosiveHighly explosive Cone shapedCone shaped Formed by layers of lava and ashFormed by layers of lava and ash

Mt. Rainier, WashingtonMt. Rainier, Washington

Mt. Fuji, JapanMt. Fuji, Japan

Mt. St. Helens, WashingtonMt. St. Helens, Washington

CinderconesCindercones

Low silica lavaLow silica lava High levels of gasHigh levels of gas ““Fire-fountain” eruptionsFire-fountain” eruptions Commonly found on the Commonly found on the

flanks of shield volcanoesflanks of shield volcanoes Made from a pile of rock piecesMade from a pile of rock pieces Structurally weakStructurally weak

Pu'u ka Pele, HawaiiPu'u ka Pele, Hawaii(on the flanks of Mauna Loa)(on the flanks of Mauna Loa)

Floreana Island, Galapagos

Puu OO, HawaiiPuu OO, Hawaii

AaAa

lava that is thick and sharplava that is thick and sharp

Pahoehoe:Pahoehoe:

lava that forms thin lava that forms thin crust and wrinklescrust and wrinkles

Pillow lavaPillow lava

lava that erupts lava that erupts under water, has a under water, has a round shaperound shape

Blocky lavaBlocky lava

cooler, lava that cooler, lava that does not travel far does not travel far from eruption, from eruption, jagged when it jagged when it dries.dries.