GEOLOGY 101 – The Earth – David Boutt
September 26, 2008
This is a pyramid exam, in which you take the same exam twice. The first time, you will be given 30 minutes to
answer the questions by yourself, without using books or notes. Please hold your answer sheet quietly until
asked to hand it in.
After the first answer sheet is handed in, you may change seating and answer the same questions on the second sheet,
this time consulting in small groups (less than 8 students each) with your colleagues, and your books and
notes. Please turn the second sheet in at the front of the class when you're done, and SHOW YOUR ID as
you do.
Your final grade is weighted with the first (solo) exam worth 75% and the second, 25%.
INSTRUCTIONS - Read carefully 1) Complete Student ID Sections (LAST NAME, then First Name + ID NUMBER) FOR BOTH EXAM
ANSWER SHEETS!
2) Mark in the sensing circles carefully with soft #2 "lead" pencil, and avoid erasure.
3) Each question constitutes 4 points each, 100 points total each exam, weighted as above.
4) Only one correct answer to each question.
5) Suggestions: Look for KEY words in any question. Answer all the ones you're sure of, then go back and work
on the rest.
1)
The unifying geological theory which explains the nature and behavior of Earth's lithosphere is:
(a)
radioactivity
(b)
plate tectonics
(c)
the hydrologic cycle
(d)
uniformitarianism
(e)
geologic time
2)
In the whole Earth, the four most common elements are oxygen, silicon, magnesium, and _____.
(a)
copper
(b)
lead
(c)
iron
(d)
zinc
(e)
carbon
3) The distinction between the crust and mantle is based on a difference in _____; the distinction between
the lithosphere and asthenosphere is primarily on the basis of a difference in _____.
(a)
chemistry (mineral content); degree of physical rigidity
(b)
color; chemistry (mineral content)
(c)
degree of physical rigidity; chemistry (mineral content)
(d)
chemistry (mineral content); chemistry as well.
(e)
carbon
4)
Wegener proposed continental drift after he observed evidence from fossils, glacial deposits, and the
fit of the continents that suggested all of the continents were once _____.
(a)
aligned north to south along the prime meridian during the late Cenozoic
(b)
aligned east to west along the equator during the late Mesozoic through the Cenozoic
(c)
combined to form a supercontinent (he termed Rodinia) in the Proterozoic
(d)
combined to form a supercontinent (he termed Pangaea) in the late Paleozoic through the Mesozoic
(e)
subducted beyond redemption
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5)
6)
Mechanical and chemical weathering act together
(a)
in a negative feed-back cycle.
(b)
by alternating expansion and contraction.
(c)
in a manner described in a redox equation.
(d)
by action of burrowing organisms and the growth of plants.
(e)
in a positive feed-back cycle.
Away from mid-ocean ridges the oceanic crust increases in:
(a)
age
(b)
depth
(c)
all of these
(d)
density
(e)
thickness
7)
Slab-pull occurs because subducting slabs are _____.
(a)
less mafic, and therefore less dense, than surrounding asthenosphere
(b)
cooler, and therefore more dense, than surrounding asthenosphere
(c)
hotter, and therefore more dense, than surrounding asthenosphere
(d)
cooler, and therefore less dense, than surrounding asthenosphere
(e)
under extensional stress
8)
Continental coastlines that occur within the interior of a tectonic plate are called _____.
(a)
integrated margins
(b)
internal margins
(c)
passive margins
(d)
active margins
(e)
inert margins
9)
When molten material freezes so quickly that the atoms do not have sufficient time to produce an
orderly arrangement, the resulting material is termed a _____
(a)
volatile
(b)
crystal
(c)
mineral
(d)
natural glass
(e)
organic molecule
10)
Which is not one of the major rock types:
(a)
metamorphic
(b)
biogenic
(c)
sedimentary
(d)
igneous
(e)
b and c
11)
Most rock-forming minerals are:
(a)
carbonates
(b)
oxides
(c)
sulfides
(d)
silicates
(e)
none of these
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(12-15) For the next four questions, select the mineral or chemical group in (a) to (e) below which is
thought to represent the major Earth zones:
(a)
(b)
(c)
(d)
(e)
limestone
mostly olivine
mostly Fe
olivine, pyroxene, plagioclase
feldspar, quartz
12) C inner core [choose from (a) to (e) above]
13) B mantle [choose from (a) to (e) above]
14) E continental crust [choose from (a) to (e) above]
15) D oceanic crust [choose from (a) to (e) above]
16)
Internal heat of the Earth fuels these types of processes:
(a)
erosion and weathering
(b)
weathering, and formation of magma
(c)
sediment deposition, and plate tectonics
(d)
hydrologic and hydrothermal
(e)
plate tectonics, and magma formation
17)
If body of igneous (source) rock is subjected to partial melting, the magma that is produced is
expected to be _____.
(a)
identical in chemical composition to the source rock
(b)
more mafic than the source rock
(c)
more silicic than the source rock
(d)
denser than the source rock
(e)
contain green minerals favored by phrogs of the asthensphere
18)
A fine-grained igneous rock of intermediate composition would be:
(a)
obsidian
(b)
granite
(c)
andesite
(d)
basalt
(E) diorite
19)
A wide range of igneous rock compositions is generated by:
(a)
partial melting
(b)
fractional crystallization
(c)
source rock composition
(d)
assimilation
(e)
all of these
20)
Wherever mid oceanic ridges have been sampled, the bedrock is
(a)
marine mud.
(b)
sandstone.
(c)
granite.
(d)
limestone.
(e)
basalt.
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21)
Granites are chemically distinct from gabbros, but are similar in their modes of emplacement because
(a)
they are both present at mid-ocean ridges.
(b)
they are both extrusive igneous rocks.
(c)
they are members of the transoceanic series.
(d)
they are both intrusive igneous rocks.
(e)
they are both metamorphic rocks.
Using the following diagrams (and their respective letters) to answer the questions below. For all
questions: D – none of the above, E – all of the above
B
A
C
22. At which boundary are the relative densities of the interacting crusts important to overall
behavior? B
23. At which boundary is decompression melting the most important factor for generating
magma?
A
24. Which boundary is likely to have the largest earthquakes associated with it? C
25. At which boundary is crusted destroyed?
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B