2. volcanism:any activity that includes the movement of magma toward the surface of the Earth volcano: place where magma reaches the surface

4. magma: liquid, molten rock underground lava: magma that reaches the surface lost gas, gained rock

5. MID-OCEAN RIDGE: occurs where plates are moving apart lava flows out smoothly and fluidly from cracks

7. SUBDUCTION ZONE: occurs at subduction boundaries usually explosive and erupted material is mostly lava

9. HOT SPOTS: areas of volcanic activity in the middle of a lithospheric plates

10. Hawaiian Islands are an example

13. two types of lava: felsic: much silica (Rhyolitic), light-colored, slow moving (viscous), continental crust

14. mafic: low silica (basaltic), dark-colored, fast moving (least viscous), oceanic crust

15. Pahoehoe (puh- HOEEE-hoeee): thin mafic lava. –usually hardens with wrinkled surface –means “ropey” in Hawaiian Pahoehoe Lava

16. Aa (AH-ah): sharp block shapes of hardened mafic lava. –caused by rapid cooling on surface of lava –breaks into jagged chunks Aa Lava

17. PahoehoeLava

18. Pahoehoe

19. Aa

20. Pillow lava from Hawaii

21. many magmas contain dissolved gases that are given off water vapor, carbon dioxide (CO 2 ), sulfur (S) magmas with more gases have more explosive eruptions

22. tephra:solid fragments ejected from a volcano ash (<2mm) bombs lapilli (<64mm) blocks Sometimes called pyroclastic material

24. lapilli

25. bombs

27. blocks

29. Vent: opening from which lava flows Crater: funnel-shaped pit or depression at top of volcano Caldera:craters whose walls have collapsed

30. composed of quiet lava flows form gently sloping, dome- shaped mountain basaltic (mafic) magma

31. largest = Mauna Loa in Hawaii

32. Made mostly of tephra and other rock particles Formed from explosive eruptions Not very high, narrow base, steep sides Rhyolitic (felsic) magma

34. built up of alternating layers of rock & lava explosive eruptions at first with tephra, then quiet with lava forms large, cone-shaped mountains made of rhyolitic & basaltic magma

35. Mount Fuji