Volcanoes Effect on Earth

An Explosive Impact Flows and Fallout Characteristics ◦ Can flow like an avalanche ◦ Can mix with water to form mudslides ◦ Knock down trees and buildings ◦ Dam up river valleys

Climate Changes Volcanic ash and sulfuric gases reach atmosphere Blocks out Sunlight Lower atmospheric temperature leads to wet mild summers and long cold winters

Types of Volcanoes Shield Cinder Cone Composite or Stratovolcano

Shield Nonexplosive Built by layers of low silica lava Runny lava layers spread out over great distance Gradual sides with a wide base, not very steep

Cinder Cone Moderately explosive eruptions Small cones made of pyroclastic material Steeper slopes with narrow base Erodes quickly ◦ Pyroclastic material is not cemented together with lava

Composite or Stratovolcano Formed by explosive eruptions followed by non-explosive outpourings of lava Combination leaves alternating layers of pyroclastic material and lava Broad, wide bases and sides Steep towards the top

Craters and Caldera Crater ◦ Top of the central vent, funnel shaped pit Funnel shape due to: ◦ Explosions ◦ Material erupting out of vent ◦ Collapse of material from rim back into vent Caldera ◦ Magma chamber empties and roof collapses causing ground to sink

Volcanic Formations Lava Plateau ◦ Massive outpouring of lava ◦ Erupts from long cracks called fissures ◦ Non-explosive type of eruption Geyser ◦ Hot water and steam that erupts from ground Batholith ◦ Mass of rock formed when a large body of magma cooled in the Earth Volcanic Neck ◦ Magma hardens in central pipe of volcano