1. volcano-an opening in Earth’s surface that erupts gases, ash, and lava.
2. Earth has more than 600 active volcanoes
3. an active volcano is one that has erupted in recorded history
4. the world’s most active volcano is Kilauea on the Island of Hawaii. It has been erupting for over 25 years.
5. Iceland is known as the “Land of Fire and Ice”, because it is so far north and has several active volcanoes. Iceland is part of the Mid-Ocean Ridge.
Iceland Eruption 1 Iceland Eruption 2
6. Volcanoes are dangerous because of flowing lava, but also because of volcanic ash, dust, and poisonous gases. Ash can cause buildings to collapse and cause lung damage.
7. pyroclastic flow-volcanic ash, rocks, and other matter (but not lava) rushing down the side of a volcano
8. Deep inside the Earth, heat and pressure melt rocks into a liquid called MAGMA.
9. Magma is less dense than the rock around it so it slowly “floats” to the Earth’s surface. Can take thousands of years to reach the surface.
10. vent-magma flows out of the Earth through an opening called a vent.
11. magma that reaches the Earth’s surface is called lava.
12. lava that cools and hardens on the Earth’s surface forms igneous rocks.
13. crater-the steep bowl-shaped area around a volcano’s vent
14. volcanoes often form where plates are moving apart (divergent) or are coming together (convergent)
15. Mid-Atlantic Ridge is a divergent plate boundary. When plates move apart, long, deep cracks called rifts are formed. Lava flows from the rift, cools quickly because of the cold seawater.
16. volcanoes also form at subduction zones caused by convergent boundaries. Convergent boundary volcanoes usually have more explosive eruptions.
17. hot spots are unusually hot areas of the crust where magma has melted into the crust, they are NOT near plate boundaries.
18. Hawaiian Islands are formed by volcanoes caused by a hot spot.
19. Yellowstone National Park is also a hot spot.
20. three types of volcanoes are shield, cinder cone, and composite.
21. shield volcanoes are built up from quiet eruptions of basaltic lava that spreads out in flat layers. Hawaiian Islands are shield volcanoes.
22. cinder cone volcanoes are formed by explosive eruptions throwing lava and rock high into the air. Rocks and solidified lava drop from the air, form the steep, loosely packed sides of the volcano.
23. composite volcanoes are a combination of quiet and explosive eruptions.
24. Ring of Fire is an area of frequent earthquakes and volcanic eruptions that circle the Pacific Ocean. It follows the plate boundaries.
25. fault-area where rocks break and move because of plate movement, faults can cause breaks and shifts in rock layers.
26. strike-slip faults are found along divergent boundaries moving in opposite directions.
27. fault-block mountains are formed by huge faults