Geology Test 1 Answers – Flashcards
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uniformitarianism
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the concept that the processes that have shaped Earth in the geologic past are essentially the same as those operating today "the present is the key to the past"
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hypothesis vs. theory
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hypothesis: a tentative explanation that is then tested to determine if it is valid theory: a well-tested and widely accepted view that explains certain observable facts
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4 spheres of the Earth
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1. geosphere (solid rock) 2. hydrosphere (water) 3. atmosphere (gaseous) 4. biosphere (life)
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what are the 2 energy sources of the Earth?
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1. internal heat: -heat left over from huge amounts of energy released during the formation of the Earth -mountains/volcanoes -radioactive decay 2. external heat: -solar energy -controls climate -permits life -weathering and erosion
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name the theory that describes the origin of planet Earth
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nebular theory: a model for the origin of the solar system that supposes a rotating nebula of dust and gases that contracted to form the sun and the planets
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name the layers of the Earth
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1. lithosphere: the rigid outer layer of the earth that consists of the curst and the upper mantle 2. asthenosphere: soft, weak layer 3. transition zone: a zone marked by a large increase in density 4. lower mantle: very strong, very hot rocks 5. outer core: liquid outer layer inner core: solid inner layer
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lithosphere vs. asthenosphere
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lithosphere: (rock sphere) consists of the entire crust plus he uppermost mantle and forms the Earth's relatively cool, rigid outer shell asthenosphere: (weak sphere) located below the lithosphere and includes temperature/pressure which results in hight amounts of melting
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What are the two most abundant elements in the Earth's crust?
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oxygen and silicon
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inner vs. outer core
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inner core: solid inner layer of the core outer core: liquid outer layer of the core
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Name the 3 types of rocks
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1. igneous rocks: -rock formed from the crystallization of magma -cooling and solidification of molten rock 2. sedimentary rocks: rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified 3. metamorphic rock: rock formed by the alteration of preexisting rock deep within the earth (still in solid state) by heat, pressure, and chemically active fluids
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rock cycle
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a model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes
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Who proposed the continental drift hypothesis?
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Alfred Wagner
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continental drift hypothesis
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-a hypothesis which suggested that all present continents once existed as a single supercontinent -200 million years ago the supercontinent began breaking into smaller continents which then drifted into their current positions
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List the pieces of evidence that early geologists used to prove the continents were once part of a large super continent
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1. fossils: identical fossils of organisms were found across now separated continents 2. rock types and geological features: Appalachian mountains were found in different areas 3. ancient climates: glaciers in the tropics/coal found in the north 4. continental jiqzaw puzzle: all continents prove to fit together
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plate tectonics
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a theory which proposes that Earth's outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself
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Name and describe the 3 types of plate boundaries.
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1. convergent plate boundaries: boundary in which two plates move together or the collision of two plates together to create a mountain system 2. divergent plate boundaries: boundary in which two plates move apart resulting in an upwelling of material in the mantle and the creation of a new seafloor 3. transform plate boundaries: boundary in which two plates slide past one another without creating or destroying the lithosphere
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Which type of convergence will result in continental volcanic arc?
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oceanic-continental convergence
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Which type of convergence will result in volcanic island arc?
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oceanic-oceanic convergence
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Which type of convergence will result in mountain building event?
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continental-continental convergence
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List the pieces of evidence that support plate tectonics
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1. ocean drilling: sediments increase in age with distance from the ridge crest 2. hot spots ; mantle blumes 3. paleomagnetism 4. magnetic reversals ; seafloor spreading
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What drives plate motion?
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convection in the mantle
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mineral
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a naturally occurring, inorganic crystalline material with a unique chemical structure
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mineral properties
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1. color: most noticeable but not most reliable 2. luster: how light reflects from the mineral 3. streak: color of a substance when ground into a fine powder 4. hardness: a measure of the resistance to scratching 5. cleavage: tendency of some minerals to break along flat, parallel cleavage plains 6. any break in a mineral not along a cleavage plane 7. crystal shape: reflects the way its atoms are packed together
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what are the 2 types of luster?
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1. metallic: reflective like silver, gold, brass, copper 2. non-metallic: unlike metal objects ex: waxy, pearly, satiny, earthy
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unit cell
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the smallest group of atoms, ions, or molecules that form the building blocks of a crystal
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mineral polymorph
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Minerals with identical composition but different crystalline structures - ex: diamond and graphite made entirely of carbon atoms
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magma vs. lava
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magma: a body of molten rock found at depth, including any dissolved gases and crystals lava: magma that reaches the Earth's surface
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intrusive vs. extrusive igneous rocks
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intrusive igneous rocks: igneous rock formed beneath the Earth's surface extrusive igneous rocks: igneous rock formed when magma solidifies at Earth's surface
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aphanitic
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-fine grained texture -rapid rate of cooling -microscopic crystals -extrusive
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phaneritic
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-course graine texture -slow cooling -visible crystals -intrusive
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porphyritic
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-large crystals (phenocrysts) are embedded in a matrix of smaller crystals (groundmass) -intrusive followed by extrusive
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vesicular
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-usually aphasic rock that contains voids left by gas bubbles that expect as the lava cools -extrusive
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glassy
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-very rapid cooling -ions are frozen in place before they can unite in an orderly crystalline structure -extrusive
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pyroclastic
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-fragmental texture -forms from the consolidation of individual rock fragments ejected during explosive eruptions -extrusive
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pegmatitic
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-exceptionally course-grained -formed in the late stages of crystallization of magmas (pegmatites) -intrusive
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Name the four composition groups in igneous rocks
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1. granitic (Celtic) 2. andesitic (intermediate) 3. basaltic (magic) 4. ultramafic
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how do we name igneous rocks?
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-based on texture and mineral composition -mineralogy is influenced by the chemical composition of the parent magma -texture results form cooling history
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What is the most common intrusive igneous rock in Earth's crust?
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granite
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What is the most common extrusive igneous rock in Earth's crust?
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basalt
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How is magma generated from solid rock?
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1. increase in temperature of crustal rocks 2. decrease in pressure 3. addition of water
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How can magmas change composition?
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1. crystal settling and magmatic differentiation 2. assimilation and magma mixing 3. partial melting
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Name the hurricanes that have made landfall in the US or one of its territories this fall.
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-harvey -irma -maria -jose
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Which direction do hurricanes spin in the northern hemisphere?
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counter clockwise
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storm surge
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the abnormal rise of the sea along a shore as a result of strong winds
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Which country experienced two major earthquakes in September?
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Mexico
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The earthquake off the western coast of Mexico was recorded in which type of tectonic plate boundary?
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convergent
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The mission of Cassini was to study which planet and its moons?
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saturn
