Hour Exam II

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Hour Exam II problem questions
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Difficulty .75

• 2. The red soils of the Athens region are red
  because of which reaction
• A. Dissolution of carbonates
• CaCO3 (calcite) H2CO3 Ca2 HCO3-
• B. Hydrolysis of Fe-Mg silicates (not balanced)
• (Mg,Fe)2SiO4 H2CO3 O2 Mg2 Fe2O3.
  HCO3- H4SiO4
• C. hydrolysis of feldspar (not balanced)
• (K,Na)AlSi3O8 (orthoclase) H2CO3 H2O
• Na K H4SiO4 Al2Si2O5(OH)4 (kaolinite)
  2 HCO3-
• D. None of the above

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When exposed to AtmosphereFe2 Becomes Fe3
(in Fe2O3) and Is red
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Difficulty 0.62
3. The CO2 in H2CO3 in the above reactions is
derived from A. the atmosphere B. the
oceans C. the mineral calcite D. all of the
above
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In the atmosphere, H2O CO2 H2CO3, carbonic
acidproduced by mixing of water vapor and CO2
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Difficulty .74
5. Earthquakes with relatively deep foci, gt 50
km, were critical in the formulation of plate
tectonic theorythese earthquakes only occur
at A. divergent margins B. convergent
margins C. transform margins D. at all plate
boundaries
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Earthquakes are concentrated along plate
boundaries, And deep earthquakes are found only
in subduction zones At convergent margins
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In the Aleutians A well-defined Benioff-Wadati Zo
ne exists But to the East there Are no
deep Earthquakes Why?
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Earthquakes occur along surface of subducted
plate And thus get deeper as distance from
trench increases
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Difficulty .74
10. The San Andreas Fault that runs through San
Francisco is a A. Convergent plate boundary B.
Divergent plate boundary C. Transform plate
boundary D. Has nothing to do with plate
tectonics
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Earthquakes are concentrated along plate
boundaries, And deep earthquakes are found only
in subduction zones At convergent margins
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San Andreas fault is The transform
boundary Between North America And Pacific plates.
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And it is a major concern To LA and SF
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Difficulty 0.72
12. If we had no convergent plate margins but
still had divergent margins and transform
margins then A. The earths surface area would
be contracting B. The earths surface area would
be expanding C. It would make no difference, the
earths surface area would be constant
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No subduction no consumption of surface
plates, earths surface area increases
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Difficulty 0.61
13. Most earthquakes occur on the same side of
the deep sea trench as the volcanoes A.
True B. False C. Rarely is this true D. There
is no hard and fast rule
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Earthquake foci are located near surface of
s Subducted plate
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Thus in The Aleutians Earthquakes Occur north Of
trench
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Difficulty 0.74
14. Earthquakes associated with volcanoes are A.
typically small but numerous B. rare but very
strong C. there are no earthquakes associated
with volcanoes D. none of the above
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Earthquakes at Mt St Helens Big eruption less
Than magnitude 3
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Volcanic activity And earthquakes Are associated
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Difficulty 0.78
17. Earthquakes in plate interiors A. never
occur B. are rare and always small C. are
uncommon but can be quite large D. are more
common than along plate boundaries
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Earthquake hazards
1886 Charleston SC earthquake
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Seismic risk map- reds and yellows are areas
where a Major quake could occur in the next 50
years (New Madrid 1811-12 ..3 earthquakes gt 8
magnitude)
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1 week earthquake Activity in USnote Activity
in New Madrid zone In mid-continent
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Difficulty .79
20. At ocean-continent convergent margins,
volcanoes form A. on the ocean plate B. on the
continental plate C. can occur on either
plate D. there are no volcanoes
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(No Transcript)
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Difficulty .75
21. Many hotspots such as Hawaii A. are
examples of extensive volcanism at a convergent
plate boundary B. are examples of extensive
volcanism at a transform plate boundary C.
are examples of extensive volcanism at a
divergent plate boundary D. are examples of
extensive volcanism in plate interiors
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Hawaii occurs in the middle of the Pacific plate
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Difficulty 0.71
22. New ocean crust is formed by A. basaltic
volcanism along mid ocean ridges B. basaltic
volcanism at deep sea trenches C. basaltic
volcanism along transform faults D. all of the
above
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New basaltic ocean crust is formed at the
mid-ocean ridges
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Eruption occurs Along a central valley At the top
of the mid- Ocean ridge
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Difficulty .79
27. The mechanism by which volcanic eruptions can
cause climate cooling is A. due to the added
water vented into the atmosphere by the
volcano B. due to reflection of sunlight by ash
and acid droplets in the upper atmosphere C.
volcanoes actually cause climate warming due
to the injection of hot gases into the
atmosphere D. due to the injection of CO2 into
the atmosphere
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Mt. Pinatubo eruption PHillipines, 1991
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Mt. Pinatubo, managed to Distribute droplets of
sulfuric Acid around the globe, and Cooled the
planet about 0.5o C
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As shown by this graph
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Difficulty 0.33
29. Magmatism at subduction zones results
from A. melting of the hot, subducted plate B.
the fluxing action of water released from the
subducted plate C. Convection currents beneath
ocean ridges D. none of the above
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This drawing shows a 3-dimensional model of
Volcano distribution
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Melting T of earth materials (rocks, minerals)
increaseswith increasing pressure
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However, if you add water, melting temperature is
loweredsignificantly
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Hydrated, ocean crust is ultimately subducted
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So the crust is hydrated and when it is subducted
it
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Dehydrates, and that water lowers the
meltingtemperature of the mantle
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Release of water triggers melting in the
overlying mantle wedge and this is the source
of convergent margin volcanism