Earth: An Introduction to Physical Geology, 11e (Tarbuck)
Chapter 14 Convergent Boundaries
14.1 Multiple-Choice Questions
1) What is the definition of orogenesis?
A) Subduction of an oceanic plate beneath a continental plate
B) Ionic exchange between calcium and oxygen
C) Emplacement of metallic ores via hydrothermal metamorphism
D) Processes that collectively form a mountain belt
2) Most mountain ranges are the result of ________ stress.
A) Compressional
B) Tensional
C) Shear
3) According to the plate tectonics model, most global mountain ranges are associated with
which kind of plate boundary?
A) Divergent
B) Convergent
C) Transform
4) ________ contain large quantities of preexisting sedimentary and crystalline rocks that have
been faulted and contorted into a series of folds.
A) Fault block mountains
B) Mid-ocean ridges
C) Compressional mountains
D) Submarine trenches
5) Which of the following regions of a subduction zone are characterized by thick sequences of
relatively undeformed sedimentary rocks?
A) Volcanic island arc
B) Forearc region
C) Suture
D) Transform fault
6) Which style of convergent boundary will characterize an Andean-type mountain building
event?
A) Where oceanic lithosphere subducts beneath oceanic lithosphere
B) Where continental lithosphere subducts beneath continental lithosphere
C) Where oceanic lithosphere subducts beneath continental lithosphere
D) Where continental lithosphere subducts beneath oceanic lithosphere
7) Which of the following locations is a remnant of a forearc basin?
A) Death Valley, CA
B) Lake Baikal, Siberia
C) Snake River Plain, ID
D) Great Valley, CA
8) How can subduction result in the emplacement of batholiths?
A) Partial melting of the subducting plate creates magma
B) Decompression melting of the plate creates magma
C) Friction of descending plate creates magma
D) Pillow basalts get subducted with plate and forced into overriding plate
9) Which type of volcanic material will dominate the eruptions along a continental volcanic arc?
A) Basaltic lavas
B) Andesitic lavas and pyroclastic materials
C) A mix of rhyolitic and basaltic materials
D) Rhyolitic lavas and pyroclastic materials
10) A ________ is a crustal fragment that has been transported by plate tectonics and has
adhered to an overriding plate.
A) Terrain
B) Guyot
C) Xenolith
D) Terrane
11) Which of the following locations is composed largely of accreted terranes?
A) Illinois
B) Hawaii
C) California
D) Colorado
12) What is a suture?
A) A landmass accreted to a continent through subduction
B) The zone where two continents are welded together
C) The region of a mid-ocean ridge where it is bisected by a transform boundary
D) A fold-and-thrust belt created through convergence
13) Which mountain range consists of the youngest collisional mountains on Earth?
A) Himalayas
B) Andes
C) Grand Tetons
D) Appalachians
14) Which of the following statements best characterizes the Valley and Ridge Province of the
Appalachian Mountains?
A) Deeply eroded, late Mesozoic upwarping mountains
B) Sedimentary strata folded at in the late Paleozoic Era
C) Continental volcanic chain along a subduction zone
D) Fault-block mountains developed from rifting of North America from Africa
15) Which of the following statements best characterizes the geology of the Pacific coastal
regions of western North America up into Alaska?
A) Divergent rifting creating deep, wide valleys with grabens
B) Collision of a massive subcontinent of old igneous and metamorphic rocks, resulting in fold-
and-thrust mountains that are still growing
C) Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent
D) Metamorphosed accretionary wedges
16) What are fault-block mountains?
A) Mountains formed through folding and thrusting of the crust
B) Mountains consisting of exposed batholiths
C) Mountains that form by erosion of streams
D) Mountains formed through crustal extension
17) Which U.S. region is made up of a series of half-grabens producing nearly parallel mountain
ranges?
A) Appalachian Mountains
B) Basin and Range
C) Colorado Plateau
D) Valley and Ridge Province
18) Which of the following best describes the formation of the Ural Mountains of Russia?
A) Marine sediments that had collected in a basin were compressed and uplifted as the former
Asian and European plates merged
B) Marine sediments were sheared along a transform boundary between the Eurasian and
African plates
C) A continental volcanic arc formed as two microcontinents collided and subducted
D) The landscape was pulled apart by rifting and flood basalts piled up on the landscape
19) Which orogeny is largely responsible for creating the modern Rocky Mountains?
A) Nevadan Orogeny
B) Taconic Orogeny
C) Laramide Orogeny
D) Alleghanian Orogeny
20) Which of the following best explains why some fault-block mountains have an elevated
topography?
A) Stretching and thinning of the lithosphere allowed for it to sit higher on the mantle
B) Large volumes of rock were thrust on top of the area
C) Flood basalts stacked up in the region
D) Subduction folded and uplifted the mountain ranges to extensive heights
21) A mountain range with peaks as high as 14,000 feet above sea level has formed. As time
passes, erosion wears down the mountains. How will isostacy affect the crust?
A) The surrounding landscape will rise
B) The mountain range will rebound
C) The mountain range will be depressed
D) Nothing will change the elevation of the area
22) Which of the following terms describes the increasing downward force on basal rocks as a
mountain continues to grow?
A) Isostacy
B) Delamination
C) Accretion
D) Gravitational collapse
23) Which of the following best describes the effect of convective flow on the elevation of
Earth’s major landforms?
A) Convective flow adds more material to the base of the lithosphere, making it downwarp
B) Rotation of convecting mantle material smoothes out wrinkles in the surface
C) Hot rising material upwarps the landscape whereas downward flow causes downwarping
D) Subduction of oceanic plates disrupting the convective flow on the mantle, resulting in hot
spots burning through the crust
24) Which of the following is believed to be responsible for uplifting southern Africa 1,500
meters higher than what would be expected for a stable continental platform?
A) Microcontinents
B) Isostacy
C) Orogenesis
D) Superplume
25) Why would geologic mapping be difficult in an area dominated by accreted terranes?
A) The geology is so similar that it would be difficult to determine terrane boundaries
B) Each terrane is geologically distinct, but also highly deformed
C) Isostatic rebound would result in gravitational collapse to make them indistinct
D) Terranes are very old and terribly eroded
26) How would the angle of subduction of a tectonic plate influence the location of a volcanic
arc?
A) The steeper the angle, the closer the arc would form to the trench
B) The shallower the angle, the closer the arc would form to the trench
C) The angle of subduction doesn’t affect the location of the volcanic arc
14.2 True/False Questions
1) The American Cordillera runs from Georgia through Maine and into Canada.
2) Most mountain ranges formed through cooling of the Earth’s crust, which resulted in
wrinkling as it contracted.
3) Volcanic island arcs created as a result of subduction are not considered mountain ranges.
4) The Cascade Volcanoes are a continental volcanic arc.
5) The Andean Volcanoes are a volcanic island arc chain.
6) Deep-ocean trenches will remain free of sediment because it all gets deposited in the forearc
region.
7) The depth of deep-ocean trenches is closely related to age: the younger the subducting plate,
the deeper the trench.
8) Volcanic island arc activity is short-lived and as a result will only produce tiny islands.
9) The subduction and melting of an accretionary wedge will result in a secondary magma.
10) Forearc basins will consist of thick sequences of highly deformed sedimentary rocks.
11) Passive continental margins will have a well-developed forearc and back-arc basin system.
12) Instead of subduction down into the mantle, the Indian subcontinent was thrust beneath
Tibet, helping to significantly raise the landscape.
13) Fault-block mountains are the result of tensional stress.
14) Fault-block mountains form only along divergent plate boundaries.
15) Because the Indian subcontinent is still colliding with the Eurasian Plate, the Himalayas are
still actively forming.
16) Accreted terranes that are adjacent to each other will generally have similar geologic
histories until the point where they accrete. After that, their geologic histories will differ.
17) As mountains continue to rise in elevation, the processes of erosion and mass wasting are
accelerated.
14.3 Short Answer Questions
1) What are the four regions of a subduction zone?
2) ________ will form as sediment collects between the accretionary wedge and the volcanic arc.
3) In what ways are the Sierra Nevada Mountains and the Andes Mountains the same in terms of
mountain formation?
4) Accretionary wedges will form along a(n) ________ tectonic boundary.
5) Describe and provide an example of a passive continental margin.
6) Explain the difference between “terrain” and “terrane.”