Question 1

What kind of geologic studies were the primary focus of the Glomar Challenger and JOIDIES Resolution's international investigations?

Accepted Answer

A)   drilling the seafloor sediments and underlying ocean crust to determine the history and development of different oceanic regions
B)   conducting swath multi- beam bathymentry and other underway geophysical surveys to map the ocean basins
C)   resource mapping on the continental shelves of Canada and other contributing member nations
D)   satellite mapping of the sea surface and spectroscopic analysis of surface currents for global current circulation and geochemistry A

Question 2

Deep- focus earthquakes are associated with________ plate boundaries.

Accepted Answer

A)   convergent (subducting) 
B)   strike- slip
C)   divergent
D)   transform

Question 3

The top of the asthenosphere is closest to the surface __________.

Accepted Answer

A)   along a transform fault
B)   along the length of a deep mantle plume
C)   along a subduction zone
D)   along a mid- ocean ridge

Question 4

This plate boundary has the least amount of volcanism.

Accepted Answer

A)   transform
B)   convergent
C)   subduction
D)   divergent

Question 5

Following technologic advances in ocean mapping that came from the Cold War in the 1950s and 1960s the new data from the ocean basins led_______ to propose the first model for seafloor spreading.

Accepted Answer

A)   Alfred Wegener
B)   Keith Runcorn
C)   Harry Hess
D)   Sir Edward Bullard

Question 6

Deep-focus earthquakes are associated with________ plate boundaries.

Accepted Answer

A)   convergent
B)   transform
C)   divergent
D)   lateral A

Question 7

The volcanoes and deep valleys of east Africa are related to a________ .

Accepted Answer

A)   continental rift along which parts of the African continent are beginning to slowly separate
B)   fault allowing Arabia to slip westward past east Africa and penetrate into Turkey
C)   continental collision zone between Africa and the Zagros Mountains along the southern margin of Eurasia
D)   transform fault aligned with the Red Sea carrying the Arabian and African blocks in opposite directions A

Question 8

What do the Appalachians have in common tectonically with the Himalayas?

Accepted Answer

A)   They are both unusual places where ocean crust overrode the continent.
B)   They are both active, convergent, continental- margin arc systems.
C)   They both formed by continent- continent collision.
D)   They both formed by continental rifting.

Question 9

Why were Wegener's continental drift ideas rejected by many contemporary and later scientists?

Accepted Answer

A)   The ocean basins were well known to be geologically young, Mesozoic and Cenozoic features.
B)   His drift mechanism seemed impossible on the basis of known physical processes.
C)   Land bridges were proven to have aided in animal and plant migrations.
D)   The gravitational attractions of the Sun and Moon were not strong enough to move the continents from the southern to the northern hemisphere.

Question 10

What important physical and chemical process occurs to subducted seafloor as it reaches a depth of 100 to 150 kilometres depth in the upper mantle?

Accepted Answer

A)   Heat from the surrounding mantle drives off water and other volatiles from the slab, which escape upwards, lowering the melting point of the overlying asthenospheric mantle.
B)   The cooling of the ocean crust from the cold, deep ocean water of the trenches causes the subducted crust to freeze the mantle, cracking and freezing it to generate the largest earthquakes.
C)   It experiences nearly a doubling in its density as the subducted basalt recrystallizes to peridotite.
D)   The subducted seafloor entirely melts generating a line of explosive volcanoes.

Question 11

In the nomenclature of J. Tuzo Wilson, a very long- lived magma source rising from deep in the mantle is called a(n)  __________.

Accepted Answer

A)   melt welt
B)   old flame
C)   hot spot
D)   basalt fount

Question 12

The "big bend" in the Hawaii- Emperor seamount chain occurred at about 45 m.y. ago. What is the most likely explanation for this change in the orientation of the hot spot track across the Pacific plate?

Accepted Answer

A)   The hot spot abruptly changed its direction. It used to move straight south, and since 45 m.y. ago it has been moving SE through the upper mantle.
B)   The Devil put this line of volcanoes here to confuse us and subvert us from the true path. Everyone knows Earth isn't really that old.
C)   From Cretaceous through 45 my. (Eocene) , the Pacific seafloor used to move northwards as it subducted down a trench near the present Aleutians. Since then the Kurile- Kamchatka trench began subducting and the Pacific plate began moving NW instead.
D)   They are two unrelated hot spot tracks that intersect. Originally there was an Emperor hot spot, then it died while the Hawaiian hot spot started up and moved in a new direction.

Question 13

Deep- focus earthquakes, those between 300 and 700 km below the surface, occur only in association with ___________.

Accepted Answer

A)   mid- ocean ridges
B)   hot spots
C)   subduction zones
D)   transform faults

Question 14

Which of the following is not part of the accepted driving mechanism of plate tectonic motions?

Accepted Answer

A)   The Earth's unequal distribution of internal heat is what drives the mantle convection and provides the heat engine.
B)   All of the heat for the mantle convection comes from small amounts of radioactive elements in the inner core.
C)   Solid state convective flow in the rocky mantle, warm regions rising and cold regions sinking, is the basic driving force for plate motions.
D)   Oceanic plates descend and constitute the downward- moving portion of Earth's internal convective flow.

Question 15

What is the inclination of Earth's magnetic field as recorded in a recent lava flow on a volcano in northern Peru?

Accepted Answer

A)   nearly vertical and pointing south
B)   nearly horizontal and pointing north
C)   nearly vertical and pointing north
D)   nearly horizontal and pointing south

Question 16

A typical rate of seafloor spreading in the Atlantic Ocean is__________ .

Accepted Answer

A)   2 centimetres per year
B)   20 metres per year
C)   2 kilometres per year
D)   2 metres per year

Question 17

From the list below, which contribution did J. Tuzo Wilson make to Plate Tectonic theory?

Accepted Answer

A)   that the largest earthquake zones were over dipping oceanic plates
B)   the existence of mid- ocean ridges and the correlation of magnetic stripes to seafloor spreading
C)   the existence of fracture zones in the ocean crust, and intraplate hot spots
D)   the rifting of continents like Pangaea and Gondwanaland

Question 18

Where is the inclination of Earth's magnetic field horizontal?

Accepted Answer

A)   at the equator
B)   latitudes between 45 and 50 degrees
C)   at the north and south poles
D)   in the Bermuda triangle

Question 19

Why is so much mafic magma erupted along mid- ocean ridges?

Accepted Answer

A)   The subducting, oceanic slab sinks so deep that eventually it melts, producing massive quantities of mafic magma.
B)   Basaltic mantle under the ridge is hot enough to completely melt if seawater is added.
C)   Lowered pressures decrease the temperatures at which mafic magma can partially melt from massive, extensive, rising plumes of mantle peridotite.
D)   The mantle beneath the ridges is enriched in thorium, uranium, and potassium, causing strong heating due to energy from radioactive decay.

Question 20

The lithospheric plates in modern plate tectonic theory differ significantly from Wegener's continental drift hypothesis in that _________

Accepted Answer

A)   they are significantly thinner
B)   we now know that the plate motions are driven by massive magnetic reversals
C)   several of the largest plates include both continental and oceanic crust
D)   it is the oceans that do all of the moving, not the continents

Exam 3: Igneous Rocks

What kind of geologic studies were the primary focus of the Glomar Challenger and JOIDIES Resolution's international investigations?

Correct AnswerverifiedA

Deep- focus earthquakes are associated with________ plate boundaries.

Correct AnswerverifiedShow Answer

The top of the asthenosphere is closest to the surface __________.

Correct AnswerverifiedShow Answer

This plate boundary has the least amount of volcanism.

Correct AnswerverifiedShow Answer

Following technologic advances in ocean mapping that came from the Cold War in the 1950s and 1960s the new data from the ocean basins led_______ to propose the first model for seafloor spreading.

Correct AnswerverifiedShow Answer

Deep-focus earthquakes are associated with________ plate boundaries.

Correct AnswerverifiedA

The volcanoes and deep valleys of east Africa are related to a________ .

Correct AnswerverifiedA

What do the Appalachians have in common tectonically with the Himalayas?

Correct AnswerverifiedShow Answer

Why were Wegener's continental drift ideas rejected by many contemporary and later scientists?

Correct AnswerverifiedShow Answer

What important physical and chemical process occurs to subducted seafloor as it reaches a depth of 100 to 150 kilometres depth in the upper mantle?

Correct AnswerverifiedShow Answer

In the nomenclature of J. Tuzo Wilson, a very long- lived magma source rising from deep in the mantle is called a(n) __________.

Correct AnswerverifiedShow Answer

The "big bend" in the Hawaii- Emperor seamount chain occurred at about 45 m.y. ago. What is the most likely explanation for this change in the orientation of the hot spot track across the Pacific plate?

Correct AnswerverifiedShow Answer

Deep- focus earthquakes, those between 300 and 700 km below the surface, occur only in association with ___________.

Correct AnswerverifiedShow Answer

Which of the following is not part of the accepted driving mechanism of plate tectonic motions?

Correct AnswerverifiedShow Answer

What is the inclination of Earth's magnetic field as recorded in a recent lava flow on a volcano in northern Peru?

Correct AnswerverifiedShow Answer

A typical rate of seafloor spreading in the Atlantic Ocean is__________ .

Correct AnswerverifiedShow Answer

From the list below, which contribution did J. Tuzo Wilson make to Plate Tectonic theory?

Correct AnswerverifiedShow Answer

Where is the inclination of Earth's magnetic field horizontal?

Correct AnswerverifiedShow Answer

Why is so much mafic magma erupted along mid- ocean ridges?

Correct AnswerverifiedShow Answer

The lithospheric plates in modern plate tectonic theory differ significantly from Wegener's continental drift hypothesis in that _________

Correct AnswerverifiedShow Answer

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