2 What is it?A volcano is a weak spot in the crust where magma is expelledTwo boundaries: divergent, convergent
3 Types of eruptions Explosive: More rare than non explosive More destructive than non explosiveBlows molten rock into the air-produce mostly pyroclastic materialQuiet (nonexplosive)-Most common-produced by calm flows of lava
4 What is inside? Magma chamber is a body of molten rock underground Vent: cracks in Earth’s surface
5 Silica and MagmaThe more silica that magma contains, the more explosive the eruption.Pyroclastic material: forms when magma is blasted into the air and hardens.
6 Eruptions and climate change As volcanic ash and gases spread through the atmosphere, they can block enough sun to cause global temperatures to drop
7 Types of volcanoesShield: forms from quiet eruptions, creates a wide-based, gently sloping mountainCinder cone: explosive eruptions, tall, narrow mountain, formed from pyroclastic materialComposite: formed from alternating quiet and explosive eruptions. Also called a Stratovolcano.
8 Other landforms created Craters: funnel shaped pits near the top of a central ventCalderas: large semi-circular depression that forms when magma chamber below has been emptied.Lava Plateau: a landform caused by repeated eruptions of lava spread over a large, flat area.
9 stagesActive: smoking, active volcano: lava, smoke coming out or will soonDormant: sleeping volcano. Nothing happening but couldExtinct: dead volcano, unlikely to erupt again.