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| a phaneritic (plutonic) rock composed of 95% olivine and less than 5% pyroxine and Ca-rich pagioclase would be classified as |
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| an aohanitic (volcanic ) rock composed of predominantly Ca-rich plagioclase and pryoxene would |
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| diorite may contain ______ quartz |
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| what kind of plate margin exist today in East Africa |
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| convergent margin (ocean-continental) |
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| what type of volcanic rock would incorporate welded lithinic fragments during the eruption? |
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| why does potassium feldspar develop cheavage planes yet it is a framework silicate mineral with all its oxygen atoms shared b/w tetrapedral? |
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Definition
| this mineral has an aluminum atomin some of its tetrahedra which requires additional ionic bonds |
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Term
| why do the large Jovian planets have molecular hydrogen in their atmospheres, but the smaller terrestrial planets do not? |
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Definition
| the jovian planets are further from the sun and they hydrogen gas can condense and be held by gravity |
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| magnetic minerals that crystalize in a lava flow erupted near the equator will_____ |
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Definition
| be oriented parallel to the surface of the lava flow |
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Definition
| form when there are weak positive and negative charges on the opposite sides of molecules |
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| what are the 2 most common elements comprising the outer core |
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Definition
| Silicon (Si) and Oxygen (O) |
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| _____ flows from Mount Versuvious obliterated the Roman city of Pompeii in 79AD |
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| most mined iron ore occurs in the ____ mineral group |
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| the silicon (Si): Oxygen (O) ration i the mica crystal structure is _____ |
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| valencies within the silicate tetrahedra of the mica structure are satisfied ______ |
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Definition
| by ionic bonds with available cations |
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| which oxygen atoms in the above tetrahedron would likely form ionic bonds with available cations b/w sillicate sheets (refer to the black arrows shown on above diagram for answers) |
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| many metallic ore bodies, such as lead, silver and copper occue in the _____ mineral group |
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| the columbia plateau is composed of rock rich in |
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| which structral component of the Cascadia subduction zone is represented by the Olympic Mts |
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| a partial melt of the asthenosphere will not rise toward the surface b/c ______ |
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Definition
| the above statement is incorrect b/c an asthenospheric melt will rise toward the surface |
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Term
| which of the following statements is true about pahoehoe basalts? |
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Definition
| pahoehoe basalts are ropy textured; pahoehoe basalts are less viscous than aa basalts |
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Term
| why does th Juan de Fuca plate subduct at a shallower angle under the North American plate compared to the Pasific plates angle of subduction the Eurasian plate near Japan |
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Definition
| none of the above are correct b/c the pasific plate subducts at a shallower angle |
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| the most widely accepted explaination for the earths magnetic field is _____ |
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Definition
| a movement of electrons in the molten iron of its outer core |
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Term
| what is the significance of (OH) in the mica crystal structure |
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Definition
| it is water likely incorporated during the subduction process |
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Term
| why does the topographic expression of all the Hawaiian island become progressively lower towards the northwest? |
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Definition
| the ocean lithosphere is lighter over the hotspot and it floats higher towards the northwest |
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Term
| what kind of tectonic setting is represented by yellowstone park |
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Definition
| hotspot underlying continental crust |
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Term
| meteorites that strike the earth are predominantly composed of _____? |
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Definition
| iron-nickel and silicate minerals |
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Term
| why do seismic waves decelerate as they enter the "low velocity zone" |
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Definition
| the "low velocity zone" is at the pressure melting temperature tempterature for the earth's mantle |
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Term
| during differentiaion of the earth into its compositional zones heat was generated from _____ |
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Definition
| kinetic energy of impacting planetesimals; compressional heating during condensation; radioactive heating |
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Term
| what mechanism have geologists proposed to expain the uplift of the Colorado Plateau and the rifting of Nevada and Utah? |
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Definition
| a spreading ridge was subducted under California and is now upwelling beneath the Basin and Range |
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Term
| transform plate boundries are typically associated with______ |
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Definition
| divergent margins where the rate of spreading is different along segements of the spreading ridge |
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Term
| what is the signifince of the change in direction of the Hawaiian islands and the Emperor Seamount |
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Definition
| the tectonic plate on which both island chains sit changed directions |
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Term
| a shield volcano has a lower slope angle than a strato (composite) volcano b/c _____ |
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Definition
| its basaltic lava flows have lower viscosities than the andesitic flows of strato volcanoes |
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Term
| the melting temperature of basaltic magma (dry mouth) ______ |
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Definition
| decreases as pressure is reduced (as it rises) |
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| according to the above diagram, at what depth will the rising basaltic magma completely solidify |
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Definition
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Term
| the depth at which partial meltin of the asthenosphere occurs is _____ |
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Definition
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| the temp at which partial melting occurs in the asthenosphere is ______ |
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Definition
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Term
| what volcanic hazard is most commonly generated from eruptions of Mt. Rainier? |
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Definition
| pyroclastic flows; mudflows (lahar); lava flows |
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Term
| which of the following statements below is incorrect regarding metallic bonds? |
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Definition
| a and c; metallic atoms have a strong connection to their electrons, which are fixed around the nucleus; metals are generally poor conductors of heat and electricity |
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Term
| P-waves ______ as they travel through the outer core |
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Definition
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| how can we best explain the fact that the inner and outer cores are both composed of metallic iron (Fe) and nickel (Ni) yet the outer core is liquid and the inner core is solid |
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Definition
| the melting temp for Fe-Ni is lower than the geothermal gradient temp in the outer core |
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Term
| how can mantle rocks be brought to the surface of te earth, such as in the cascades or fidalgo islands |
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Definition
| there are "squeeze" to the surface along suture zones where the collision occurs |
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Term
| as magma crystalizes into igneous rock the residual melt |
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Definition
| will be come more felsic (silica rich); will yeild more explosive eruptions |
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| in the geologic techniques lab each group completed a topographic cross-sectioin of Yosemite Valley |
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| in the plate tectonics lab we observed that oceanic crust comprising the Juan de Fuca plate was being created at the spreading ridge at the rate ____ the rate of its subduction beneath the North American plate? |
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| in the minerals lab the main diagnostic criteria used for identifying the metallic mineral galena is ______ |
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| in the igneous rock lab we observed the rock andesite. it had a ______ texture. |
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