JLKR+3.1

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Vocabulary

 * volcano-** a weak part of earth's crust where magma comes out of
 * magma-** is a mixture of rock-forming substances, gases, and water
 * lava-** when magma comes out of the volcano
 * ring of fire-** a volcanic belt
 * island arc-** when a volcano makes a island
 * hot spot-** when magma in the mantle melts through the crust

What is a Volcano?

 * a volcano is a weak spot in the crust where magma comes to the surface
 * magma is a molten mixture of rock-forming substances, gases, and water from the mantle
 * when magma comes to the surface, it's called lava
 * after the lava cools, it hardens to become solid rock

Locations of Volcanoes

 * volcanoes occur in belts, or chains
 * one major volcanic belt is the Ring of Fire
 * most volcanoes occur along diverging plate boundaries, or in subduction zones around the edges of oceans

Volcanoes at Diverging Plate Boundaries

 * volcanoes form along the mid-ocean ridge
 * only in a few places, as in Iceland and the Azores Islands, do the volcanoes of the mid-ocean ridge rise above the ocean's surface

Volcanoes at Converging Boundaries

 * many volcanoes occur on islands, near boundaries where two plates collide
 * the resulting volcanoes create a string of islands called an island arc

Hot Spot Volcanoes

 * a hot spot is an area where magma from deep within the mantle melts through the crust
 * hot spots often lie in the middle of continental or oceanic plates far from any plate boundaries
 * hot spots can also form under continents