SOLVED

31) The 1943 eruption of Paricutin in Mexico was characterized by ________. A) mudflows and explosive ash eruptions B) welded-tuff deposition and caldera formation C) cinder cone building and basaltic lava D) pyroclastic eruptions and nueé ardente flows 32) The average composition of rocks comprising a large composite cone or stratovolcano is similar to a(n) ________ magma. A) basaltic B) ultramafic C) andesitic D) rhyolitic 33) A ________ volcano is a very large, gently sloping mound composed mainly of basaltic lava flows. A) composite B) stratospheric C) cinder cone D) shield 34) Which of the following best describes Shiprock, a famous volcanic feature in New Mexico? A) a very recently active, basaltic cinder cone B) an extinct, highly symmetrical, composite volcanic cone C) the eroded remains of a volcanic pipe and radiating dikes D) an extinct, massive, rhyolitic shield volcano 35) Which region has the greatest concentration of currently active volcanoes? A) the coastal plain of western Africa B) European Russia and Siberia C) the area surrounding the Red Sea D) the circum-Pacific area 36) The recent (geologically) volcanic activity in Yellowstone National Park is ________. A) related to plate subduction B) related to a divergent plate boundary C) related to a transform plate boundary D) related to intraplate, hot spot volcanism 37) The Icelandic volcanoes are related to plate tectonics because ________. A) they lie on a spreading center where two plates are converging B) they lie on a subduction zone where two plates are converging C) they lie on a spreading center where two plates are moving apart D) they lie along a subduction zone where two plates are diverging 38) Which one of the following best describes volcanism in the Cascade Range, northwestern United States? A) related to a mantle hot spot B) related to plate subduction C) related to a mid-oceanic ridge system D) related to deep, transform faults 39) Which of the following statements best describes the big Hawaiian volcanoes? A) They lie directly above a transform plate boundary that cuts deeply into the mantle. B) They lie directly above an active subduction zone where the Pacific plate is sinking into the mantle. C) They lie along the crest of the East Pacific Rise, a mid-ocean ridge or spreading center. D) They are situated in the interior of a large, Pacific plate above a hot spot deep in the mantle. 40) What volcanic events formed Crater Lake, Oregon? When did they take place? A) A powerful explosion blew away the top of a stratovolcano; 10 million years ago. B) The crater of a large, extinct cinder cone filled with water; 5 million years ago. C) Landslides and volcanic mudflows dammed the Mazama River; 500 years ago. D) Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago. 41) Which one of the following shows the correct order (left to right) of decreasing magma viscosity? A) rhyolite, andesite, basalt B) andesite, rhyolite, basalt C) basalt, rhyolite, andesite D) basalt, andesite, rhyolite 42) Why do magmas rise toward Earth’s surface? A) Magmas are more viscous than solid rocks in the crust and upper mantle. B) Most magmas are richer in silica than most crustal and upper mantle rocks. C) Magmas are mainly liquid and contain dissolved fluids such as water; most are less dense than the adjacent solid rock. D) all of the above