Cordillera Review Sheet

xMULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What is the definition of cordillera? 1) _____ A) Ionic replacement B) Backbone C) Subduction of an oceanic plate D) Emplacement of metallic ores 2) Most mountain ranges are the result of ________ stress. 2) _____ A) tensional B) shearC) compressional 3) According to the plate tectonics model, most global mountain ranges are associated with which kind of plate boundary? 3) _____ A) Convergent B) Divergent C) Transform 4) The American Cordillera's location is the span from ________. 4) _____ A) Georgia to Newfoundland B) Maine to Canada C) Texas to Arizona D) Southernmost South America to Alaska 5) In which location on a continent would one be likely to find young mountain belts (less than 100 million years old)? 5) _____ A) On the continental shield B) In the center of the continent C) Along the margins of the continent D) On the stable platform 6) ________ contain large quantities of preexisting sedimentary and crystalline rocks that have been faulted and contorted into a series of folds. 6) _____ A) Mid-ocean ridges B) Fault-block mountains C) Compressional mountains D) Submarine trenches 7) The largest of the shields is the ________ shield. 7) _____ A) Australian B) Angara C) Baltic D) African 8) Which of the following regions of a subduction zone is characterized by thick sequences of relatively undeformed sedimentary rocks? 8) _____ A) Volcanic island arc B) Transform fault C) Suture D) Forearc region 9) Put the four regions of a subduction zone in order from the convergent boundary landward toward the continental interior.9) _____ A) Volcanic arc, deep-ocean trench, forearc region, back-arc region B) Deep-ocean trench, forearc region, volcanic arc, back-arc region C) Forearc, back-arc, deep-ocean trench, volcanic arc D) Back-arc region, volcanic arc, forearc, deep-ocean trench 10) What are the four regions of a subduction zone? 10) _____ A) Tensional, compressional, shear, convection B) Oceanic, volcanic, continental, island C) Accretionary wedge, terrane, accumulation zone, submarine canyon D) Volcanic arc, deep-ocean trench, forearc, and back-arc 11) Which factor(s) will most influence the depth of deep-ocean trenches? 11) _____ A) Compressive force B) Temperature and density of the plate C) Density and composition of the mantle beneath D) Rate of convection 12) The Cascadia subduction zone off the coast of Washington and Oregon famously lacks a well-defined deep-ocean trench. Why might this be the case? 12) _____ A) The descending plate is warm and buoyant, so it subducts shallowly. B) Compression from the convergent boundary has squeezed any potential trench closed. C) There is a shallow angle of plate subduction, as well as large quantities of sediment infill. D) There is a massive amount of sediment fill from the Columbia River basin. 13) How does the angle of subduction affect the dimensions of the forearc basin? 13) _____ A) Steep angle of subduction leads to a narrow forearc basin B) Steep angle of subduction leads to a wide forearc basin C) Shallow angle of subduction closes the forearc basin D) Shallow angle of subduction leads to a wide forearc basin 14) What is the source of the sediments in a forearc basin? 14) _____ A) Carbonate reefs B) Sediments washed from the landmass C) Glacial sediments D) Continental sediments and pyroclastic materials 15) If a back-arc basin is associated with a volcanic island arc, what tends to develop there? 15) _____ A) Long, linear sea B) Rift valley C) Wide continental shelf D) Submarine trench 16) If a back-arc basin is a region related to a subduction zone, how can such an extensional basin form near a boundary defined by compression? 16) _____ A) Rising magma is softening the crust, allowing it to stretch. B) Compression ceases before extension takes over. C) A plate subducting at an extremely shallow angle is pushing against the back-arc region. D) Trench rolls back as the old, dense subducting plate sinks. 17) Which of the following is an example of a continental volcanic arc? 17) _____ A) Cascade Volcanoes B) Aleutian Volcanoes C) Hawaiian Volcanoes D) Icelandic Volcanoes 18) Which of the following is an example of a volcanic island arc? 18) _____ A) Andean Volcanoes B) Hawaiian Volcanoes C) Cascade Volcanoes D) Aleutian Volcanoes 19) In oceanic-continental convergence, a volcanic arc is created on the ________ and is the result of ________ rising up from a subducting plate. 19) _____ A) oceanic plate; sediment B) continental plate; magma C) oceanic plate; magma D) continental plate; sediment 20) ________ is the driving force in orogenesis. 20) _____ A) Subduction B) Convection C) Extension D) Temperature 21) A ________ will form as sediment collects between the accretionary wedge and the volcanic arc. 21) _____ A) back-arc basin B) deep-ocean trench C) forearc basin D) continental shelf 22) Accretionary wedges will form along a(n) ________ tectonic boundary. 22) _____ A) convergent B) transform C) divergent 23) Which style of convergent boundary will characterize an Andean-type mountain building event? 23) _____ A) A rift zone B) A trench C) A back-arc basin D) A forearc basin 24) A divergent boundary will be characterized by what feature? 24) _____ A) A back-arc basin B) A rift zone C) A forearc basin D) A trench 25) Which of the following locations is a remnant of a forearc basin? 25) _____ A) Death Valley, CA B) Snake River Plain, ID C) Lake Baikal, Siberia D) Great Valley, CA 26) In what ways are the Sierra Nevada Mountains and the Andes Mountains the same in terms of mountain formation? 26) _____ A) Extension of the continent through rifting B) Downwarping of the continent due to crustal subsidence C) Emplacement of batholiths D) Crumpling of the continent through collision with another continent 27) What is an accretionary wedge? 27) _____ A) Sediments and ocean crust fragments being scraped off of a subducting plate B) Fault blocks that are slipping down due to extension in a back-arc basin C) A fan of sediments at the bottom of a deep-ocean trench D) Deformed and thrust-faulted continental lithosphere 28) Which type of volcanic material will dominate the eruptions along a continental volcanic arc? 28) _____ A) Felsic lavas B) A mix of felsic and ultramafic lavas C) Mafic lavas D) Lavas of intermediate or felsic composition 29) In Torres del Paine National Park, how was the rock near the top of the mountains metamorphosed? 29) _____ A) From intrusion of igneous rock by a sedimentary rock B) As a result of a meteorite impact (tektite) rock C) From intrusion of sedimentary rock by an igneous rock D) As a result of large-scale regional metamorphism 30) A ________ is a crustal fragment that has been transported by plate tectonics and has adhered to an overriding plate. 30) _____ A) Guyot B) Terrane C) Xenolith D) Terrain 31) Which of the following locations is composed largely of accreted terranes? 31) _____ A) Hawaii B) California C) Colorado D) Illinois 32) What is a suture? 32) _____ A) The zone where two continents are welded together B) The region of a mid-ocean ridge where it is bisected by a transform boundary C) A landmass accreted to a continent through subduction D) A fold-and-thrust belt created through convergence 33) Which mountain range consists of the youngest collisional mountains on Earth? 33) _____ A) Grand Tetons B) Appalachians C) Andes D) Himalayas 34) Fold-and-thrust belts are the result of ________ stress whereas fault-block mountains are the result of ________ stress. 34) _____ A) compressional; tensional B) shear; tensional C) tensional; shear D) shear; compressional 35) As India is colliding with Asia, the margin of Asia is experiencing significant deformation. What is happening to the rocks that are being deformed? 35) _____ A) They are being subducted into the mantle B) They are being displaced to the southeast to make up Southeast Asia C) They are being melted to become magma plutons D) They are breaking off to form microcontinents 36) Which of the following statements best characterizes the geology and structure of the Appalachian Mountains? 36) _____ A) Sedimentary strata folded at in the late Paleozoic Era B) Fault-block mountains developed from rifting of North America from Africa C) Continental volcanic chain along a subduction zone D) Deeply eroded, late Mesozoic upwarping mountains 37) The ________ Orogeny is one of three events that formed the modern Appalachian Mountains. 37) _____ A) Tibetan B) Laramide C) Taconic D) Cordilleran 38) Put the three orogenic events of the Appalachian in order from oldest to youngest. 38) _____ A) Taconic Orogeny, Laramide Orogeny, Acadian Orogeny B) Laramide Orogeny, Taconic, Alleghanian Orogeny C) Taconic Orogeny, Acadian Orogeny, Alleghanian Orogeny D) Alleghanian Orogeny, Taconic Orogeny, Acadian Orogeny 39) Which of the following describes the events of the Taconic Orogeny? 39) _____ A) Closing of the marginal sea caused a volcanic arc to be thrust over the continent B) The sea along North America closed completely as Africa collided with North America C) North America collided with a microcontinent as the marginal sea continued to close D) The rifting of Pangaea opened the modern Atlantic Ocean 40) Which of the following statements best characterizes the geology of western North America, starting in California and extending through British Columbia and up into Alaska?40) _____ A) Collision of a massive subcontinent of old igneous and metamorphic rocks, resulting in fold-and-thrust mountains that are still growing B) Metamorphosed accretionary wedges C) Divergent rifting creating deep, wide valleys with grabens D) Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent 41) The Atlantic Coastal Plain is underlain by a portion of which continent? 41) _____ A) Africa B) Europe C) South America D) Australia 42) What are fault-block mountains? 42) _____ A) Mountains formed through folding and thrusting of the crust B) Mountains that form by erosion of streams C) Mountains formed through crustal extension and normal faulting D) Mountains consisting of exposed batholiths 43) What kind of stress is responsible for creating fault-block mountains? 43) _____ A) Tension B) Shear C) Compression 44) Which U.S. region is made up of a series of high-angle normal faults producing nearly parallel mountain ranges? 44) _____ A) Appalachian Mountains B) Basin and Range Province C) Valley and Ridge Province D) Colorado Plateau 45) Which of the following best describes the formation of the Ural Mountains of Russia? 45) _____ A) The landscape was pulled apart by rifting and flood basalts piled up on the landscape B) A continental volcanic arc formed as two microcontinents collided and subducted C) Marine sediments were sheared along a transform boundary between the Eurasian and African plates D) Marine sediments that had collected in a basin were compressed and uplifted as the former Asian and European plates merged 46) Which orogeny is largely responsible for creating the modern Rocky Mountains? 46) _____ A) Alleghanian Orogeny B) Laramide Orogeny C) Nevadan Orogeny D) Taconic Orogeny 47) Which of the following best explains why some fault-block mountains have an elevated topography? 47) _____ A) Large volumes of rock were thrust on top of the area B) Subduction folded and uplifted the mountain ranges to extensive heights C) Thinning of the lithosphere resulted in upwelling of hot mantle rock and greater lithospheric buoyancy D) Flood basalts stacked up in the region 48) A mountain range with peaks as high as 14,000 feet above sea level has formed. As time passes, erosion wears down the mountains. How will isostacy affect the crust? 48) _____ A) The mountain range will rise B) The surrounding landscape will sink C) The mountain range will be depressed D) Nothing will change the elevation of the area 49) Which of the following is a real-world example of isostatic adjustment? 49) _____ A) Downwarping of the continent in Illinois due to subduction of slabs of oceanic lithosphere B) African continent bulging upward when moving over a mantle plume C) Rebound of the landmass around Hudson Bay after glacial ice sheets have retreated D) Continental margin of North America extending to create a forearc basin in California 50) Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow? 50) _____ A) Delamination B) Isostacy C) Accretion D) Gravitational collapse 51) Which of the following is believed to be responsible for uplifting southern Africa 1,500 meters higher than what would be expected for a stable continental platform? 51) _____ A) Microcontinents B) Superplume C) Isostacy D) Orogenesis 52) Why would geologic mapping be difficult in an area dominated by accreted terranes? 52) _____ A) Terranes are very old and terribly eroded B) The geology is so similar that it would be difficult to determine terrane boundaries C) Each terrane is geologically distinct, but also highly deformed D) Isostatic rebound would result in gravitational collapse to make them indistinct 53) How would the angle of subduction of a tectonic plate influence the location of a volcanic arc?53) _____ A) The shallower the angle, the closer the arc would form to the trench B) The angle of subduction doesn't affect the location of the volcanic arc C) The steeper the angle, the further the arc would form to the trench D) The steeper the angle, the closer the arc would form to the trench