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This guide reviews the three main types of volcanoes: shield, cinder, and composite. Shield volcanoes have broad, gently sloping sides formed by nonexplosive eruptions of low-viscosity basaltic lava. Cinder volcanoes are smaller, steep-sided formations created from ejected materials that accumulate around a vent, featuring more viscous magma with higher silica and water content, leading to explosive eruptions. Composite volcanoes, the largest of the three, are formed from alternating layers of volcanic fragments and lava, characterized by violent eruptions and significant hazards to humans and the environment.
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Let’s Review! • Shield Volcano • Broad, gently sloping sides • Nearly circular base • Form because of layered basaltic lava accumulation during nonexplosive eruptions • (basaltic lava: low viscosity small amounts of gases and silica) • “Oozing” eruptions
Let’s Review! • Cinder Volcano • Small; most are less than 500 m high • Formed by material ejected by a vent that falls back to Earth and accumulates around the vent • Steep sides • Its more viscous magma contains more water and silica than that of the magma fueling shield volcanoes • Contains large volumes of gases • More explosive than shield
Let’s Review! • Composite Volcano • Formed when layering alternates between volcanic fragments and lava • Magma contains large amounts of silica, water, and gases • Much larger than cinder-cone volcanoes because of their violent eruptions • Very dangerous to humans and environment
Name that Volcano!! 1.) Shield 2.) Cinder 3.) Composite
