Chapter 6: Volcanoes Study Guide

Chapter 7: Volcanoes Study Guide Name ______Period ____ Section 7-1 Volcanoes and Plate Tectonics (pages 200-203) 1. A volcano is a weak spot in the crust where ______comes to the surface. 2. A molten mixture of rock-forming substances, gases and water from the mantle is referred to as ______. 3. When magma reaches the surface, it is called ______. 4. The ______is a major volcanic belt formed by a long chain of volcanoes that rim the Pacific Plate. 5. Most volcanoes form along which 2 plate boundaries?______and ______6. Volcanoes form along the mid-ocean ridge when ______7. True or False? Volcanoes can form along diverging plate boundaries on land. ______8. True or False? Many volcanoes form near converging plate boundaries where oceanic crust subducts. ____ 9. Volcanoes at boundaries where 2 oceanic plates collide create a string of islands called an ______. 10. Give 3 examples of island arcs. ______11. Circle the letter of the types of plates that collided to form the Andes Mountains on the west coast of South America. a. two oceanic plates b. a continental plate and an oceanic plate c. a continental plate and an island plate d. two continental plates. 12. A ______is an area where magma from deep within the mantle melts through the crust like a blow torch. 13. The Hawaiian Islands formed as the ______plate drifted over a hot spot. 14. True or False? Hot spots only form under oceanic crust. ______Section 7-2 Properties of Magma (pages 205-208) 15. A substance the cannot be broken down into other substances is called a(n) ______. 16. True or false? When frozen water melts, it is undergoing a physical change. ______17-18. Circle the statements that indicate a chemical property. a. Water boils at 100°C under normal conditions. c. an iron chair will develop rust if oxygen combines with the iron. b. When paper is burned, it forms ashes. d. A basketball is larger than a baseball. 19. The greater the viscosity, the ______a liquid flows. The ______the viscosity, the more easily a liquid flows. 20-21. Circle the letter of each liquid that has a relatively low viscosity. a. milk b. molasses c. ketchup d. orange juice e. milkshake 22. The viscosity of magma is determined by the amount of ______and its ______. 23-24. Circle the letter that is true about silica. a. It is formed from oxygen (O) and nitrogen (N). c. It is rarely found in the crust. b. It makes magma thicker. d. It produces light-colored lava. 25. The rock ______forms from light-colored lava. Low-silica magma forms rocks like______. 26. The higher the temperature, the ______the viscosity. 27. Hot, fast-moving lava is called ______. 28. Cool, slow-moving lava is called ______. Viscosity of Magma Temperature Silica Content High 29. 30. 31. Higher 32. Section 7-3 Volcanic Eruptions (pages 209-216) 33. True or False? Magma usually forms in the asthenosphere (part of lithosphere).______34. True of False? Liquid magma rises until it reaches the surface or until it becomes trapped beneath layers of rock. ______35. During a volcanic eruption, the force of the expanding gases pushes magma from the ______through the ______until it flows or explodes out of the ______. 36-37. Circle the letters of the features that all volcanoes share. a. pocket of magma b. cracks to the surface c. side vents d. crater 38. A ______is the area covered by lava as it pours out of a vent. 39. A ______forms at the top of a volcano around the central vent. 40. True or False? The pipe of a volcano is a horizontal crack in the crust. ______41. The 2 main factors that determine whether a volcanic eruption will be quiet or explosive are the magma’s ______content and ______. 42. High- viscosity magma causes ______eruptions. 43. Volcanic ______is made up of fine rocky particles as small as a speck of dust. 44. Pebbles sized particles are called ______. 45. Particles ranging in size from the size of a baseball to the size of a car are called ______. 46. A ______occurs when an explosive eruption hurls out a mixture of ash, cinders, bombs and a mixture of REALLY HOT & deadly gases (melts your skin). 47. True or False? The activity of a volcano may last from less than a decade to more than 10 million years. ___ 48-50. Volcanoes are dangerous because their lava flows start ______and bury everything in their path. If it becomes wet from rain, volcanic ash becomes very heavy and causes ______to collapse. Engines of cars and ______stall if the ash clogs the engine. Due to snow-capped volcanoes mixing with intense heat, ______and ______often occur. The ash and poisonous ______can be fatal to humans, animals and plants. 51. The three stages of a volcano: ______dead or very unlikely to erupt again ______erupting/showing signs of erupting ______sleeping, but expected to erupt again 52-53. Geologists who study volcanoes are called volcanologists. They use instruments like the ______to monitor changes in elevation around volcanoes. They monitor any ______that might be escaping from the volcano and also take temperature readings of underground ______. Small earthquakes are a sign that ______is moving under the surface.

Section 7-4 Volcanic Landforms (pages 217-223) Match each landform with its description. ______54. shield volcano A. high, level area formed by repeated lava flows ______55. cinder cone B. mountain formed by lava flows alternating with explosive eruptions ______56. batholith C. forms when magma hardens in volcano’s pipe, (looks like giant tooth) ______57. lava plateau D. hole left by the collapse of a volcanic mountain ______58. caldera E. gently sloping mountain formed by repeated lava flows ______59. volcanic neck F. cone-shaped mountain formed from ash, cinders and bombs ______60. composite volcano G. mass of rock formed when magma cools inside crust and the layers of rock surrounding it erode 61. When volcanic rock erodes and creates soil, it is very fertile due to the nutrients ______and ______, both of which the enrich soil around volcanoes. 62. “Geo” means ______and “therm” means heat, so geothermal means heat from the earth. 63. When groundwater is heated by a nearby body of magma or hot rock deep underground, it forms ______. When hot water and steam become trapped and suddenly sprays above the surface it is called a ______. 64. Geothermal energy is a tremendous renewable energy resource. The steam is piped into a ______, which spins a generator. California and New Zealand take advantage of this resource.