211, Geology Physical Geology First Exam February 5, 2004
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PART 1: Multiple choice: (60 points) Please circle the letter that best answers or completes the question. 1. Which boundary is the surface upon which lithospheric plates move? A. The Mohorovicic Discontinuity (the Moho) B. The asthenosphere lithosphere boundary C. Gutenberg's Discontinuity D. The crust The average geothermal gradient in Earth's crust is which of the following? A. 25C/km B. 35C/km C. 45C/km D. 15C/km The basic structural unit in all silicate minerals is the... A. Polymorph B. Metallic bond C. Silicate tetrahedron D. Chloride ion The core of Earth consists of ________. A. A solid inner and a solid outer component B. A solid outer and a liquid inner component C. A liquid inner and a liquid outer component D. A solid inner and a liquid outer component As compared to aphanitic igneous rocks, phaneritic rocks ________. A. Cooled more rapidly B. Cooled less rapidly C. Are still molten D. Aren't cool Which of the following controls the viscosity of erupting lavas? A. Si02 content B. K20 content C. Al203 content D. Mg0 content. What best explains seamount guyot tracks across an expanse of ocean A. Motion of a hot spot beneath continental lithosphere B. Motion of oceanic lithosphere over a stationary hot spot C. Ancient astronauts D. An ancient mid-ocean ridge
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Geology 211, Physical Geology First Exam February 5, 2004 11.
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Submarine mafic eruptions commonly exhibit _____________. A. Porphyritic textures B. Lava fountains C. Pillow structures D. Columnar joints. Igneous intrusions which cut across layered strata are termed _____________. A. Sills B. Batholiths C. Laccoliths D. Dikes. The Heliocentric theory of the solar system was championed by whom? A. Copernicus B. Ptolemy C. Eratosthenes D. Newton Where would geothermal heat flow be expected to be low? A. Along mid-ocean ridges B. At a hot spot C. At the base of the lithosphere D. In the center of a continent What discovery was made upon visiting the Mid-Atlantic Ridge in the research submersible "Alvin"? A. Pillow basalts B. Rift valleys C. An ecosystem based on energy from hot mineralized water D. The singing group "the Chipmunks" At a triple junction is a place on Earth's surface where ________. A. Three tectonic plate boundaries coincide B. Igneous, metamorphic and sedimentary rocks coexist C. Glacial ice, continental rocks, and oceanic rocks can be found together D. Three phases of matter (solid, liquid and gas) occur together in equilibrium A cross-section through the oceanic crust that is preserved on continental crust is term a(n)________. A. Gabbro B. Pillow basalt C. Sheeted dike complex D. Ophiolite
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Geology 211, Physical Geology First Exam February 5, 2004 18.
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Which tectonic feature corresponds with the deepest part of the ocean? A. A mid-ocean ridge B. A transform fault fracture zone C. A continent continent collision D. A subduction trench What can a geologist interpret from a xenolith? A. The type of country rock a magma passed through B. The temperature of the magma C. The pressure of the magma D. Ancient warrior princesses had kidney stones Which of the following characterizes the transform fault that offsets mid-ocean ridge segments? A. An abundance of shallow earthquakes B. Effusive volcanism C. All of the above D. All of the below Continental crust and oceanic crust ________. A. Never occur on the same tectonic plate B. Can transition one into the other C. Are really the same D. Always transition one into the other X-Ray diffraction is useful in the study of minerals because it allows scientists to ________. A. Determine that a mineral is solid B. Determine that a mineral is naturally occurring C. Determine that a mineral has an ordered atomic structure D. Determine that a mineral is inorganic A laccolith is ________. A. A horizontal tabular intrusion that lies parallel to surrounding layers of sedimentary rock B. A mushroom-shaped igneous intrusion C. An intrusion formed within the magma chamber of a volcano D. A vertical tabular intrusion that cuts across preexisting layers Natural glass is not considered a mineral because it ________. A. Is not homogenous B. Is organic C. Does not have a fixed crystalline structure D. Can be made synthetically as well as being a naturally occurring substance
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Geology 211, Physical Geology First Exam February 5, 2004 25.
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How does magma composition relate to volcanic eruptive style? A. Thick viscous magmas erupt in mild runny lava flows B. was replaced by the theory of plate tectonics C. was incorporated within the theory of plate tectonics D. Thick viscous magmas erupt in massive explosions of rock and ash. Which is the most common rock-forming mineral group in Earth's crust? A. Calcite B. Quartz C. Feldspars D. Clay minerals The oldest oceanic crust on the sea floor occurs ________. A. At the edges of ocean basins B. In volcanic island arcs C. Near mid-ocean ridges D. Randomly distributed over the entire ocean basin Silica tetrahedra may be coordinated to form all of the following structures EXCEPT ________. A. Long single chains B. Extensive two-dimensional sheets C. Three-dimensional frameworks D. Double helixes A(n) __________ is formed of material scraped off a descending, lithospheric plate. A. Mass movement complex B. Continental shelf, terrain complex C. Accretionary-wedge complex D. Subterranean-accumulation complex A good example of a present-day, passive continental margin is the __________. A. North flank of the East Pacific Rise B. West coast of South America C. East coast of the Japanese Islands D. West coast of Africa
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Geology 211, Physical Geology First Exam February 5, 2004 31.
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Earth's surface is protected from solar wind and cosmic radiation by ________. A. Earth's gravitational field B. The ozone layer C. Omniscient beings D. The Van Allen radiation belts Wegener's idea of continental drift was supported the following lines of evidence ________. EXCEPT A. Fossils of non-swimming organisms were found on opposite sides of the Atlantic B. Mountain belts and unique rock types were observed to link across the Atlantic C. The distribution of glacial striations and tropical sediments were consistent with Pangea D. Paleomagnetic positive and negative anomalies (stripes) preserved in the oceanic crust What is a guyot? A. A circular feature formed by impact of an asteroid on continental crust B. A flat-topped submarine volcano C. A blob-like igneous rock body that has cooled beneath the surface of the Earth D. A mushroom-shaped igneous intrusion Continental crust ________. A. Is thinner than oceanic crust B. Contains more mafic rocks than oceanic crust C. Is less dense than oceanic crust D. Is mostly basaltic in composition What does Bowen's Reaction Series describe? A. Temperature changes in a cooling magma B. Pressure changes in a cooling magma C. Compositional changes in a cooling magma D. Textural changes in a cooling magma Which of the following descriptors characterizes tectonic plates? A. They are rigid B. They are thin and hot C. They are made of continental rocks which plow through weaker oceanic rocks D. They behave like plastic solids
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Geology 211, Physical Geology First Exam February 5, 2004
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How does magma composition relate to volcanic eruptive style? A. Increasing silica content makes magmas less viscous leading to less violent eruptions B. Decreasing silica content makes magmas less viscous leading to less violent eruptions C. Increasing silica content makes magmas more viscous leading to less violent eruptions D. Decreasing silica content makes magmas less viscous leading to more violent eruptions What is the most abundant element in the crust? A. Silicate B. Iron C. Oxygen D. Aluminum One difference between lava and magma is that ________. A. Magma is cooler B. Magma is more dense C. Lava has lost volatiles D. Lava is under greater pressure Minerals that lack cleavage are said to have ________. A. A poor attention span B. Ductility C. High specific gravity D. Fracture What is a major difference between a ridge transform and a fracture zone? A. Unlike a fracture zone, oceanic crust at a transform travels in 2 directions. B. Fracture zones have multiple shallow earthquakes; transforms don't C. Fracture zones are thermally expanded; transforms aren't D. Transforms have extensive volcanic activity unlike fracture zones At a subduction zone, which of the following is NOT present? A. A volcanic arc B. A bathymetric trench C. An axial rift D. An accretionary wedge Which of the following discoveries was the result of submarine detection efforts during the Cold War? A. Sonic booms create clouds. B. Earthquakes concentrate along Mid-Ocean Ridges and ridge transform offsets. C. Magnetic stripes were found oriented perpendicular to the Mid-Ocean Ridges. D. Sea-water is a poor transmitter of sound waves.
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Geology 211, Physical Geology First Exam February 5, 2004 44.
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Coarse-grained granite is most similar in composition to fine-grained ________. A. Andesite B. Basalt C. Komatiite D. Rhyolite Which of the following is an inference you can make about any euhedral quartz crystal? A. The crystal has magical healing powers B. The crystal is a polymorph C. The crystal must have grown in an open space D. The crystal must be from Herkimer, New York
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Part 2, Short Answer: (20 points) Please write a short sentence to answer the question 46. What is the Wadati Benioff Zone?
47. Who first proposed continental drift?
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What is a black smoker?
49. What does mag...