This document provides definitions and descriptions of key terms related to volcanoes and volcanic eruptions. It discusses the types of magma and lava, including how composition affects explosiveness. Vent openings, pyroclastic material, and features like cinder cones, composite volcanoes and calderas are defined. The roles of tectonic plate boundaries and hot spots in the formation of magma and volcanoes are also outlined.

1. Chapter 8 Volcanoes Volcanic Eruptions Section 1

2. Nonexplosive Eruptions Volcanoes with Lava flows

3. Explosive Eruptions Clouds of hot debris and gases shoot out from the volcanoes

4. Magma Hot liquid material volcanoes are created in

5. Vents Holes in the Earth’s crust that magma rises through

6. Lava Magma that erupts onto the Earth’s surface

7. Pyroclastic Material Magma & fragments of rock that are blasted into the air during violent earthquake eruptions

8. Volcano A vent or group of vents combined with a buildup of lava or pyroclastic material

9. Magma - High Water Content Explosive volcanoes with high water content

10. Magma - Silica Magma that contains a large percentage of Silica

11. Blocky Lava Cool stiff lava that cannot travel far from the erupting vent

12. Pahoehoe Lava that flows like wax dripping from a candle

13. Aa Lava that has a jagged surface

14. Pillow Lava Lava that erupts underwater

15. Volcanic Blocks Largest pieces of pyroclastic material

16. Volcanic Bombs Large blobs of magma that harden in the air

17. Lapilli “Little stones” pebble-like bits of pyroclastic material

18. Volcanic Ash Particles that are less than 2 mm in diameter

19. Chapter 8 Volcanoes Volcanoes’ Effects on Earth Section 2

20. Volcanic Flows Clouds of hot ash that flow rapidly downhill like an avalanche

21. Volcanic Fallout As volcanic ash falls to the ground effects may be devastating

22. Climatic Fluctuation Ash & gases spread around the globe & block out the sun

23. Shield Volcanoes Layers of lava from repeated non explosive eruptions

24. Cinder cone volcanoes Small volcanic cones made entirely of pyroclastic material from moderately explosive eruptions

25. Composite Volcanoes Explosive eruptions of pyroclastic material

26. Crater Funnel shaped pit at the top of the central vent

27. Caldera Magma chamber volcanoes empties & roof collapses

28. Chapter 8 Volcanoes What causes Volcanoes? Section 2

29. Formation of Magma Magma forms below the Earth’s surface in a region that includes the lower crust & the upper mantle

30. Where Volcanoes Form Tectonic plate boundaries form “ring of fire”

31. Rift Deep crake forms between the plates

32. Hot Spots Tectonic plates that are directly above columns of rising magma