Deck 13: Mountain Building and Continental Frameworks

Question 1

A(n)________ convergent plate margin is associated with a volcanic island arc.

A)Andean
B)Aleutian
C)accretionary
D)collisional

Answer 1

B

Question 2

A(n)________ convergent plate margin is associated with an accretionary wedge.

A)Aleutian
B)accretionary
C)Andean
D)collisional

Answer 2

C

Question 3

The term ________ refers specifically to the collection of all geologic processes and tectonic events that are responsible for building mountain belts.

A)erogenesis
B)orogenesis
C)orthogneisses
D)rifting

Answer 3

B

Question 4

A(n)________ plate margin commonly evolves from a divergent one.

A)transform
B)passive
C)offshore
D)shallow ramped

Question 5

Volcanism along a continental arc is dominated by the eruption of ________.

A)basaltic lava flows
B)andesitic lavas and pyroclastic materials
C)rhyolitic pyroclastic materials and lavas
D)ophiolites

Question 6

Since the early Mesozoic, the ________ has been passive tectonically.

A)western margin of North America
B)western margin of South America
C)southern margin of Eurasia
D)eastern margin of North America

Question 7

Mountain belts formed from folded marine sediments by continent-continent collision, include ________.

A)Appalachians and Caledonians
B)European Alps
C)East African rift
D)NE edge of Indian Ocean

Question 8

Mountainous relief is due to the rotation and sinking of lithospheric blocks in a ________ tectonic setting.

A)extensional
B)convergent continent-ocean
C)convergent ocean-ocean
D)convergent continent-ocean

Question 9

Which of the following geologic products or processes is not a result of mountain building?

A)building of a deep sea fan of turbidites offshore from a convergent continent-ocean margin
B)downdropped extensional grabens with playa lakes
C)exposure of belts of high pressure, Precambrian, igneous and metamorphic rocks within continental shield areas
D)subsided sedimentary basins in the middle of continental cratons

Question 10

The concept of ________ includes the idea that crustal rocks are floating in a kind of gravitational balance and that their elevation depends on their density contrast to the underlying upper mantle.

A)orogeny
B)isostasy
C)subsidency
D)isotropy

Question 11

Rift valleys with mafic volcanics are ________ margins.

A)extensional
B)continent-continent
C)continent-ocean
D)ocean-ocean

Question 12

Subduction zones include all of the following except for ________.

A)deep ocean trenches
B)magma generation
C)suture zones
D)volcanic arcs

Question 13

Subduction ceases in a(n)________ type of convergent plate margin.

A)continent-ocean
B)ocean-ocean
C)accretionary
D)continent-continent

Question 14

Rugged elevations are due to crustal extension, related to underlying mantle heat or convective upwelling, in the ________.

A)East African rift
B)European Alps
C)Appalachians and Caledonians
D)NE edge of Indian Ocean

Question 15

Which mountain belt did not have a stage of continent-continent collision as it formed?

A)Andes
B)Appalachians
C)Himalayas
D)Urals

Question 16

The world's highest mountain belts result from ________ convergent plate margins.

A)transform
B)ocean-ocean
C)continent-continent
D)accretionary

Question 17

A good example of a present-day, passive, trailing, continental margin is the ________.

A)north flank of the East Pacific Rise
B)west coast of South America
C)east coast of the Japanese Islands
D)west coast of Africa

Question 18

Topographically high-standing, mountainous areas generally ________.

A)are underlain by greater than average thicknesses of lower density, crustal rocks
B)subside rapidly to compensate for erosion
C)have thicker, higher-density mantle rocks beneath them at shallow depths
D)experience rapid erosion that thins the crust and causes the area to subside

Question 19

As new layers of sedimentary or volcanic rock are added to the crust the ________.

A)elevation increases faster than the thickness
B)elevation increases by an equal amount to the thickness
C)elevation stays the same but the thickness increases
D)thickness increases faster than the elevation

Question 20

Mountain belts formed in several stages by the opening and closing of the Iapetus Ocean in the Paleozoic, include the ________.

A)Appalachians and Caledonians
B)European Alps
C)East African rift
D)NE edge of Indian Ocean

Question 21

Which would the Andean-type margin not have more of, in comparison to an Aleutian-type margin?

A)complicated crustal compressional structures
B)felsic pyroclastics
C)deformed high pressure/low temperature accretionary wedge rocks
D)subaqueous mafic pyroclastics close to the volcanoes

Question 22

Which statement comes closest to describing the isostatic compensation under convergent continental mountain belts?

A)The extra elevation of mountains, like that of icebergs above the sea, is held up by the weight of the denser material that their lower portions displace.
B)The extra elevation of mountains is maintained almost entirely by rising mantle plumes.
C)The extra elevation of mountains is accounted for by the missing mass from adjacent eroded valleys and flanking lowland areas.
D)The extra elevation of mountains is maintained by active elastic compression supplied by earthquake cycles and crustal convergence.

Question 23

The severed, upper part of a Jurassic seamount might occur as a distinctive, small terrane ________.

A)on a passive-margin continental shelf
B)in an arc of composite volcanoes far inland from a convergent margin
C)along the boundary between two Precambrian shield areas
D)in an accretionary wedge shoved onto an active, continental margin

Question 24

Active volcanic arcs above a young oceanic plate are associated with a(n)________ margin.

A)ocean-ocean
B)continent-continent
C)continent-ocean
D)divergent

Question 25

A(n)________ is a thick accumulation of sediments and small, rootless, tectonic blocks formed of material scraped off a descending, lithospheric plate.

A)mass movement complex
B)continental shelf, terrain complex
C)accretionary-wedge complex
D)subterranean-accumulation complex

Question 26

The ________ is (are)characterized by terrane accretion that has been active throughout most of Mesozoic and Cenozoic time.

A)western margin of Africa
B)southern margins of India and Australia
C)western margin of North America
D)western margin of the mid-Atlantic ridge

Question 27

On an Andean-type convergent margin, the continental block contains the ________.

A)accretionary wedge and high pressure-low temperature metasediments and metavolcanics
B)batholiths, volcanic arc, and high temperature-moderate pressure metamorphics
C)deep ocean trench and batholiths
D)rotated block faults

Question 28

Accretionary wedges are formed ________.

A)at the edge of the overriding plate against a subduction zone
B)at the base of a passive continental margin
C)on the oceanic plate side of a transform fault
D)around submarine volcanoes fed by long-lived hot spots in the mantle

Question 29

The ________ have crust about twice as thick as normal.

A)Sierra Nevada mountains in California
B)northern end of the Appalachian mountains on Cape Breton Island
C)Himalayan Range and Tibetan Plateau in northern India and SW China
D)Cypress Hills in Alberta

Question 30

When a subduction zone is established under the edge of a continent, this gives rise to an accretionary wedge, a volcanic arc, and compressional features farther inland that is called ________ margin.

A)an Aleutian
B)an Andean
C)a Himalayan
D)a passive

Question 31

Which of the following best describes the geology of the Pacific coastal regions of western North America including Alaska?

A)An earlier, continental margin broke apart and the geologically similar fragments were tectonically reassembled.
B)Geologically different, microcontinent-sized fragments and terranes, formed elsewhere, were tectonically accreted to North America.
C)A massive subcontinent of old igneous and metamorphic rocks (similar to India)was accreted during late Proterozoic time.
D)Tightly folded, continental shelf strata were squeezed between North America and the convergent, Bering-Siberian subcontinent.

Question 32

How were the Ural Mountains (Russia)formed?

A)A large dome of Archean igneous and metamorphic rocks rose up as the Eurasian plate became situated over a mantle plume.
B)Kilometres of marine strata, originally deposited in a basin between the former Asian and European plates, were squeezed, folded, and uplifted as the two collided and joined to form the Eurasian plate.
C)Normal faulting from a modern continental rift is elevating large mountain blocks above the level of the vast plains on both sides of the range and giving rise to a volcanic mountain chain.
D)An active fold and thrust belt is forming as Asia and Europe continue to converge and buckle the crust along an old tectonic suture zone.

Question 33

Prolonged convergence across Aleutian-type margins can result in the ________.

A)complete destruction of both oceanic plates
B)development of thick, continental-type crust
C)subduction of the volcanic arc
D)thinning of the lithosphere under the arc

Question 34

A(n)________ is a zone where two continents collide, often preserving slivers of oceanic lithosphere between the colliding plates.

A)passive margin
B)ophiolite
C)suture
D)terrane

Question 35

Thick blocks of crust carried toward a subduction zone ________.

A)can get sliced off the descending slab and transferred to the accretionary continental margin as an accreted terrane
B)cause the subduction zone to stop or reverse and begin subducting the other way
C)get eroded, contributing a greater than usual volume of sediments to the trench at that point
D)get uplifted to become an island on the oceanward side of the trench

Question 36

An exotic terrane created by a seamount accreted to a continental margin would be composed ________.

A)of folded, quartz sandstone and shallow water, marine limestone
B)exclusively of granite batholiths and rhyolite welded tuffs
C)mainly of organic-rich, black shales and beach-type sandstones
D)mainly of basaltic lava flows and minor, coralline limestone

Question 37

One piece of evidence for the substantial compression accompanying terrane accretion in B.C.and the Yukon is ________.

A)Pleistocene folds in the offshore crust of the Pacific plate
B)Jurassic and Cretaceous deformations in the fold and thrust belt of the Canadian Rockies in B.C.and Alberta
C)Paleozoic subsidence in the Williston Basin of Saskatchewan and Manitoba
D)Pleistocene uplift and erosion in the Canadian Shield of the Northwest Territories

Question 38

Mountains without active volcanic arcs are associated with a(n)________ margin.

A)continent-continent
B)continent-ocean
C)ocean-ocean
D)divergent

Question 39

Folded, fine grained turbidites that occur high in the Himalayas were originally deposited as sediments ________.

A)in the accretionary wedge along the southern edge of Asia
B)along the shallow shoreline and continental shelf north of India
C)on the deep ocean abyssal plain south of India
D)in a massive, Late Paleozoic syncline north of the Tibetan Plateau

Question 40

Most of mainland Alaska, over half of B.C.and the Yukon, and most of Washington, Oregon, Nevada and California are ________.

A)accreted terranes transported to the north from more equatorial regions, including: Paleozoic through Mesozoic seafloor, island arcs, submarine deposits, and displaced continental fragments
B)an Andean style arc complex, of intermediate and felsic plutonics and volcanics, that formed in Cenozoic time by subduction of Pacific plates beneath North America
C)tectonically deformed and strongly metamorphosed Early Precambrian accretionary wedge deposits from the earliest, west coast, active margin
D)the geologic equivalents of cratonic stratigraphy found all across North America, but these have been intensively deformed by episodes of convergent margin mountain building in Mesozoic and Cenozoic time

Question 41

The rock sequences and mountainous topography of the northern portion of the Appalachian Mountains ________.

A)consist of up to six different accretionary sequences, plastered onto the eastern margin of North America during the closing of the Iapetus Ocean over several stages of tectonic convergence between the Cambrian and Carboniferous
B)was made up mainly of Late Proterozoic, passive margin sedimentary strata that weren't deformed until the break up of Pangaea in the Late Carboniferous
C)is made up of extinct composite volcanoes and massive intrusions formed above a Late Precambrian subduction zone
D)were barged across the Atlantic by homesick Scottish immigrants during the Highland Clearances

Question 42

Intensely folded, thinly bedded, Paleozoic shales and carbonates cause this part of the Canadian Rockies to appear the most jagged and rough due to the easily-eroded shale interbeds.

A)Western Ranges
B)Main Ranges
C)Front Ranges
D)Foothills

Question 43

Between the original Proterozoic rifting of Rodinia and the Late Paleozoic rifting of Pangaea, how much "real estate" was added to the North American continent?

A)the entire width of the Appalachian Orogen, St.Lawrence Seaway through Nova Scotia, 600-800 kilometres
B)everything from Ontario to Alberta
C)only Newfoundland and Labrador
D)the width of Iapetus Ocean, thousands of kilometres

Question 44

In general, which of the following statements about elevated, compressive orogens is true?

A)Crust was thickened by previous mountain building; as isostatic uplift and erosion proceed, the crust is gradually reduced in thickness.
B)Crust was thinned by extensional faulting in the past; isostatic uplift and erosion cause the crustal root to gradually thicken.
C)Crust is flattened by increased atmospheric pressure over mountain belts.
D)Crust is sucked into the mantle by increased convection under mountain belts.

Question 45

During the Late Paleozoic (Devonian through Carboniferous), the tectonic and topographic configuration of the Appalachian region in eastern North America was most similar to the ________.

A)Himalayas and Tibetan Plateau
B)Andes
C)Afar Rift
D)western California

Question 46

The Humber Zone (Valley and Ridge Province in USA)of the Appalachian Mountains is characterized by ________.

A)sedimentary strata folded in late Paleozoic time
B)deeply eroded, late Paleozoic, fault-block mountains and valleys
C)composite volcanoes above a volcanic arc
D)crustal stretching as Africa and Eurasia migrated away from North America

Question 47

Under what terrane would you look to find the original rift zone tensional faults from the Proterozoic break up of Rodinia?

A)Humber Zone (Valley and Ridge Province in USA)of folded, sedimentary rocks on the eastern edge of the Appalachians
B)Dunnage Zone (Taconic phase)
C)Avalonia block (Acadian phase)
D)Meguma Zone

Question 48

Low elevation rounded mountains and hogbacks underlain by thrusts and folds in easily-eroded Mesozoic and Cenozoic strata are found in this part of the Rockies.

A)Foothills
B)Western Ranges
C)Main Ranges
D)Front Ranges

Question 49

The ________ are a geologically old mountain range folded and deformed during the Paleozoic.

A)Cascades in the northwestern U.S.and southwestern B.C.
B)Canadian Rockies
C)Appalachians of eastern North America
D)Alps in Europe

Question 50

Thick thrust sheets of massive Proterozoic and Paleozoic carbonates from glaciated peaks with steep cliffs on all sides like Castle Mountain in western Alberta are found in this part of the Rockies.

A)Main Ranges
B)Western Ranges
C)Front Ranges
D)Foothills

Question 51

What is the Meguma Zone in Nova Scotia (and similar rocks beneath the more southerly, continental shelf off the US eastern seaboard)thought to represent?

A)passive margin sequence from Gondwanaland as the Iapetus Ocean closed
B)passive margin sequence from Rodinia's rifted margin
C)Ordovician accretionary melange from the Taconic orogeny
D)Cretaceous and Tertiary shallow continental shelf deposits from North America's passive margin

Question 52

The ________ of the Appalachian orogen consists of North American, continental shelf strata deposited prior to the late Paleozoic collision with Gondwanaland (Africa).

A)Humber Zone (Valley and Ridge in USA)of folded sedimentary rocks on the eastern edge
B)Dunnage Zone (Taconic phase)
C)Avalonia bock (Acadian phase)
D)Meguma Zone

Question 53

What kind of crust was the Avalon Terrane prior to its accretion to the Appalachians in the Acadian Orogeny in the Silurian and Devonian?

A)microcontinental fragment rifted off Rodinia or Gondwanaland
B)supracrustal Iapetus seafloor sediments and Gondwanaland passive margin succession
C)ophiolite-Iapetus Ocean crustal sequence
D)island arc sequence

Question 54

What supercontinent drifted apart in the Proterozoic to form the first extensional phase of the Appalachian orogen?

A)Rodinia
B)Gondwanaland
C)Laurasia
D)Pangaea

Question 55

What ocean basin was destroyed and finally had its last sliver obducted to make the ophiolite between the Humber Zone and the Gander Terrane?

A)Iapetus
B)Atlantic
C)Arctic
D)Fundy

Question 56

Obducted ophiolite and island arc sequences are part of a ________ margin.

A)continent-ocean
B)continent-continent
C)ocean-ocean
D)divergent

Question 57

Which one of the following is an example of an isostatic movement?

A)stream downcutting following a drop in sea level
B)arching of strata at the centre of a dome
C)numerous aftershocks associated with deep-hypocentre earthquakes
D)uplift of areas recently covered by thick, continental ice sheets

Question 58

Well defined linear mountain ridges with southwesterly-dipping slopes, steep upturned bounding thrusts and intervening linear strike valleys are found in this part of the Rockies.

A)Front Ranges
B)Western Ranges
C)Main Ranges
D)Foothills

Question 59

A ________ is a ridge of steeply inclined, resistant strata exposed along the edges of an uplifted block of older rock.

A)hogback
B)hoodoo
C)monotreme
D)shellback

Question 60

The ________ is the global tectonic cycle that rifts supercontinents, developes extensive passive margins, opens ocean basins, closes ocean basins, creates new island arc or Andean crustal orogens, and finally builds new collisional mountain belts as the ocean completely closes to make a new supercontinent.

A)Convective Conga
B)Seafloor Shake Up
C)Wegnerian Break Up
D)Wilson Cycle

Question 61

What happens as the crust isostatically rises during or following a mountain building episode?

A)The deformed strata experience regional uplift.
B)Folding and thrusting continue, to accommodate the increased uplift.
C)The mantle flows out of the way to compensate for the rising crust.
D)The root continues to grow to compensate for the increasing elevation.

Question 62

Mountain uplifts can change the course and sediment load of river systems.

Question 63

Mountain belts are generally narrower than mountain ranges.

Question 64

All mountain belts are produced by some form of orogenesis.

Question 65

The Western Canada Foreland Basin and the Appalachian Foreland Basin both formed ________.

A)by passive marginal subsidence in the Early Precambrian
B)from broad regions of down-flowing cool mantle
C)in Paleozoic time from the break up of Pangaea
D)in response to crustal thickening and mountain building from terrane accretion

Question 66

The highest elevation mountain areas are underlain by the densest, strongest, and coldest crustal rocks.

Question 67

The oldest rocks are about ________ and found in ________.

A)< 5000 years; Ireland and Israel
B)1)6 billion years; compressional mountain belts on continental margins
C)1)7-1.9 billion years; island arcs within the western Pacific
D)3)5 billion years; continental shield areas, deep within continents

Question 68

What mechanism is proposed for Cretaceous subsidence of the Canadian and American prairies?

A)An underlying mantle plume suddenly quit, cooled, and subsided.
B)A subducting slab detaches from the trailing lithosphere, creating a downward flow that drags the base of the overriding continent with it.
C)A former broad monocline under the prairies eventually flattened out.
D)A large Cretaceous meteorite impacted the prairies, the evidence for which has yet to be found.

Question 69

Deep in the interior of a continental shield, an eroded belt of deformed, Precambrian, high pressure, plutonic and metamorphic rocks would most correctly be called an orogen.

Question 70

The elevation and uplift rate of mountain areas are determined isostatically by the densities and thicknesses of underlying rock layers all the way down to the mantle.

Question 71

According to the crustal, gravitational balance idea, which of the following statements is true?

A)A mountain range undergoing erosion should uplift slowly.
B)As a continental ice sheet thickens, the land beneath should uplift slowly.
C)A basin being filled with sediments should uplift slowly.
D)The crust is thicker under a low lying plain than under a high standing plateau or mountain range.

Question 72

Mountains and mountain building processes have little direct influence upon regional climate.

Question 73

As an inactive mountain belt ages, what happens to the adjacent crustal areas?

A)They uplift along with the mountains.
B)They subside in response to the added load of sediments eroded off the mountains.
C)They slide into the sea along transform faults.
D)They are subducted.

Question 74

Which statement best describes an intracratonic basin?

A)circular bowl-shaped depressions that develop well within continental interiors
B)synonymous with meteorite crater
C)a circular syncline that developed in the Canadian Rockies
D)a sag pond in the Fraser delta

Question 75

Thick, gradual accumulations of shallow water, Jurassic and younger limestones, sandstones and shales characterize the passive continental margins along the Atlantic.

Question 76

What is the evidence that the interior of North America experienced major subsidence during the Cretaceous?

A)Sea water invaded much of the continent in which marine sedimentary rocks formed.
B)Ophiolite sequences are found in the Canadian prairies.
C)Failed mid-ocean rifts occur in southern Alberta.
D)Petrified walrus tusks were discovered under Calgary.

Question 77

Turbidite sandstones with graded bedding would be common on continental shelves associated with trailing, passive, continental margins.

Question 78

What did the earliest continental crust resemble?

A)andesitic island arcs like the Aleutians
B)basaltic rift zones like East Africa
C)foreland and intracratonic basins with mature quartz-rich sandstones
D)giant protocontinents of silica-rich magmas formed from the early differentiation of Earth into crust, mantle, and core

Question 79

As new layers of rocks are added to the crust, the elevation increases faster than the crustal thickness.

Question 80

Passive, trailing, continental margins typically exhibit normal faults that were active when the original, single continent was rifted.