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Earth Science Chapter 18 Worksheet 1 Name ____________________________ Block ____________________________ Match the definitions to the correct word or term ____ 1. Plutons ____ 2. Dike ____ 3. Tephra ____ 4. Stock ____ 5. Hot spot ____ 6. Caldera ____ 7. Viscosity ____ 8. Composite volcano ____ 9. Vent ____ 10. Cinder-cone volcano ____ 11. Laccolith ____ 12. Pyroclastic flow ____ 13. Crater ____ 14. Batholith ____ 15. Shield volcano ____ 16. Sill ____ 17. Volcanism ____ ____ ____ 18. Flood basalt 19. Fissure 20. Conduit A. Relatively small, mushroom shaped pluton that forms when magma intrudes into parallel rock layers close to Earth’s surface B. Coarse-grained, irregularly shaped, igneous rock mass that covers at least 100km2 C. Pluton that forms when magma intrudes parallel rock layers D. Steep-sided, generally small volcano that is built up by the accumulation of tephra around the vent E. Opening in Earth’s crust through which lava erupts and flows out onto the surface F. Bowl shaped depression that forms around the central vent at the summit of a volcano G. Rock fragments that are thrown into the air during a volcanic eruption and fall to the ground H. Intrusive igneous rock bodies formed through mountain-building processes and oceanic-oceanic collisions I. Pluton that cuts across preexisting rocks and often forms when magma invades cracks in surrounding rock bodies J. Broad volcano with gently sloping sides built by nonexplosive eruptions of basaltic lava that accumulates in layers K. A substance’s internal resistance to flow L. Large, sloping volcano built by violent eruptions of volcanic fragments and lava that accumulate in alternating layers M. Irregularly shaped pluton that is similar to a batholith, but smaller and cuts across older rocks N. Swift-moving, potentially deadly clouds of ash, gas, and other volcanic material produced by a violent eruption O. Large crater that can form when the summit or side of a volcano collapses into the magma chamber during or after an eruption P. Unusually hot area in Earth’s mantle where plumes of mantle material rise toward the surface Q. Describes all the processes associated with the discharge of magma, hot water, and steam R. Huge amounts of lava that erupt from fissures S. A long crack in Earth’s crust T. A tubelike structure that allows lava to reach the surface Circle the letter that corresponds to the correct answer 21. Which of the following does not play a role in magma formation? a. Temperature b. Pressure c. Presence of water d. Tephra type 22. Which of the following is true? a. An increase in pressure results in a higher melting temperature of a dry substance b. A decrease in pressure increases the temperature at which a dry substance melts c. The addition of water increases the melting temperature of a substance d. An increase in pressure decreases the melting temperature of a dry substance 23. Which of the following melts to form rhyolitic magma? a. Continental crust b. Oceanic crust c. Oceanic sediment d. The upper mantle 24. Which type of pluton is completely parallel to the rock layers into which it intrudes? a. Dike b. Sill c. Laccolith d. Stock 25. The Hawaiian volcanoes formed as a result of which of the following? a. Divergence b. A hot spot c. Subduction d. Subsidence 26. Which of the following is not true? a. An increase in silica increases the viscosity of a magma b. Andesitic magma has both an intermediate gas content and explosiveness c. An increase in temperature increases a magma’s viscosity d. Basaltic magma has a low viscosity and contains little gas 27. Which of the following has broad, gently sloping sides and a circular base? a. Hot spot b. Cinder-cone volcano c. Composite volcano d. Shield volcano In the space at the left, write the word in parentheses that makes the statement correct _______________ 28. The hotter the magma or lava, the (greater, lower) is its viscosity _______________ 29. Lava that has low viscosity moves (slower, faster) than lava with high viscosity _______________ 30. Temperature and pressure (increase, decrease) with depth beneath Earth’s surface _______________ 31. The temperature at which a substance melts (increases, decreases) with the presence of water _______________ 32. Rhyolitic magma forms beneath (continental, oceanic) crust _______________ 33. Cinder-cone volcanoes have steep sides and are generally the (largest, smallest) volcanoes _______________ 34. Volcanoes associated with (divergent, convergent) plate boundaries form the Circum-Pacific and the Mediterranean Belts _______________ 35. (Laccoliths, Dikes) are plutons that cause overlying rocks to bow upward _______________ 36. (Shield, Composite) volcanoes are made of basaltic lava _______________ 37. Most of the world’s rift volcanism occurs at (divergent, convergent) boundaries Circle T if the statement is true or F if the statement is false T F 38. The fact that most of the rocks in Earth’s lower crust and upper mantle do not melt to form magma, even though the temperatures there are high enough, is explained by the effect of water T F 39. Rhyolitic magma-fueled volcanoes are especially explosive because rhyolitic magma is highly viscous and contains a large volume of trapped gas T F 40. The higher the silica content in lava, the higher the lava’s resistance to flow T F 41. Many plutons formed as a result of mountain-building processes that occurred along divergent plate boundaries T F 42. The volcanoes in the Circum-Pacific Belt form as a result of magma rising upward in faults and fractures that form as tectonic plates diverge Answer the following questions 43. Describe the three factors that affect the formation of magma 44. Discuss three ways in which magma affects the crust into which it intrudes 45. What is a volcanic crater, and how does it differ from a caldera?