Quiz 20: Mountain Belts and the Continental Crust

A Precambrian shield, an area of no sedimentary rocks, covers much of eastern and northern Canada.

The more open the folds, the less intense the deformation in a mountainous region.

Isostatic adjustment takes place during orogeny.

The region of a continent that has been structurally stable for a prolonged period of time is called the craton.

The Appalachian Mountains are an example of ocean-ocean convergence.

Orogenies are not accompanied by metamorphism and igneous activity.

Soapstone is a metamorphic rock composed of the mineral talc.

One important result of orogeny is that continental crust becomes thicker.

On the North American continent, the Appalachian Mountains extend from western Canada through the western United States into New Mexico.

A cycle of splitting of a supercontinent, opening of an ocean basin, followed by closing of the basin and collision of continents is known as a Wilson Cycle.

Delamination is the detachment of the continental crust from the oceanic crust.

In the Paleozoic Era the North American continent grew westward because of the accumulation of the Cordillera.

Frequent earthquakes are characteristic of mountain belts that are young and active.

The Andes Mountains, where the South America Plate overrides the Nazca Plate, are a consequence of ocean-continent convergence.

Mountain belts are characterized by sedimentary sequences that show little or no deformation.

Some accreted terranes were microcontinents similar to present day New Zealand.

Fold and thrust belts are found in many mountain regions.

Seismic studies indicate that continental crust beneath mountains and cratons is essentially the same thickness.

According to the concept of isostasy, lighter, less dense, continental crust "floats" higher on the mantle than denser oceanic crust.

Weathering and erosion play no role in the development of mountains.

_____ are chains thousands of kilometers long composed of numerous mountain ranges. A) Mid-oceanic ridge B) Volcanic arcs C) Back arcs D) Valley and Ridge Province E) Mountain belts

During the last couple of decades, geologist have used a _____ approach to gain insight into the growth and wearing away of mountains. A) tectonic B) erosional C) weathering D) system E) climatic

The once deep-seated roots of former Precambrian mountain belts are the _____ rock for the now stable, central part of the continent. A) cratonic B) basement C) core D) platform E) isostatic

In many mountainous regions are found ____, which are characterized by large thrust faults stacked one upon another. A) fold and thrust belts B) numerous rock types C) evidence of intrusions D) patterns of deformation E) volcanic landforms

____, intermixed granitic and metamorphic rock, may represent those parts of mountain belts that were once at even deeper levels of the crust. A) Pegmatites B) Sutures C) Migmatites D) Extensional fabric E) Subduction patterns

Frequent earthquakes, offshore trenches, and active volcanoes perched on top of older rock are all indications of ____. A) old mountain belts B) stable craton C) platform D) Precambrian shield E) active mountain ranges

Geologists believe that when the thick and high part of a mountain belt becomes too high and gravitationally unstable _____ occurs. A) massive landslides B) gravitational collapse and spreading C) volcanic eruptions D) rapid downcutting E) basalt flows

In some mountain belts the crust breaks into fault-bounded blocks resulting in _____ mountain ranges. A) fault-block B) extremely high C) extensional D) isostatically adjusted E) metamorphic

The _____ is(are) the product of oceanic-continental convergence and Earth's second highest mountain belt. A) Appalachians B) Himalayas C) Andes D) Basin and Range E) Sierra Nevada

A _____ is a group of closely spaced mountains or parallel ridges that may show a history of intrusive tectonic activity. A) volcano B) mountain range C) back-arc basin D) spreading center E) any uplifted region

The continental crust is _______ beneath mountain belts than under the craton. A) thinner B) thicker C) the same thickness D) more felsic E) more dense

Most of the world's mountains existing today are a result of ____. A) intense deformation B) isostasy C) weathering and erosion D) intense deformation and isostasy E) intense deformation, isostasy, and weathering and erosion

Extension and normal faulting take place in a mountain range ____. A) during their early stage of formation B) when rock at high level flows outward C) before folding and metamorphism D) randomly throughout the range's history E) and is always related to late stage intrusions

The region of a continent that has been structurally stable for a long period of time is called the ______. A) dome B) basin C) Precambrian shield D) craton E) mountain range

The _____ resulted from the collision of Asia and Europe. A) Alps B) Pyrenees C) Caledonide Mountains D) Ural Mountains E) Himalayan Mountains

The sedimentary sequences that form on passive margins are predominantly ____. A) shale B) limestone C) sandstones D) andesitic flows E) shale, limestone, and sandstones

Volcanic rocks, mostly _______, accumulate near a convergent plate boundary. A) shales B) sandstones C) granites D) andesites E) marbles

The Himalayan Mountains formed as the result of ______ convergence. A) ocean-continent B) arc-continent C) ocean-ocean D) arc-ocean E) continent-continent

A _____ terrane has rock types and ages that do not seem to be related to the rest of the geology of a mountain belt. A) mixed B) coupled C) partial D) integrated E) suspect

If the San Andreas Fault remains active, Los Angeles will continue northward and crash into ___. A) Alaska B) Japan C) the Imperial Valley D) British Columbia E) Hawaii

Terranes that can be shown to have traveled great distances are known as _____ terranes. A) accreted B) exotic C) suspect D) cratonic E) shield

Late stage normal faulting in a mountain range is a result of _______. A) volcanism B) igneous intrusions C) vertical uplift or extension D) sea-floor spreading E) geosyncline formation

Migmatites must have been transported much higher in the crust during and after ____. A) normal faulting B) volcanism C) emplacement of plutons D) an orogeny E) subduction

At the close of the Paleozoic, eastern North America was attached to what is now _______. A) Europe and Asia B) China and South America C) India and Antarctica D) Africa and China E) Europe and Africa

_____ is the detachment of part of the mantle portion of the lithosphere beneath a mountain belt. A) Delamination B) Mantle convection C) Terrane shift D) Isostatic adjustment E) Craton formation

_____ faults in the Tibetan plateau indicate that gravitational collapse is taking place. A) Normal B) Reverse C) Thrust D) Strike-slip E) High-angle thrust

________ beneath the Basin and Range helps to explain the extensive rhyolitic and basaltic eruptions that occurred tens of millions of years after the last orogeny. A) Obduction B) Delamination C) Wilson Cycles D) Subduction E) Thickening of the continental crust by "rooting"

The cycle of splitting of a supercontinent, opening of an ocean basin, followed by closing of the basin and collision of the continents, is known as a ________. A) Wegener plan B) Wilson Cycle C) delamination plan D) Hess Process E) Vine-Mathews system

A ______ is the source of sedimentary and volcanic material accumulating along a convergent boundary. A) subduction zone B) magmatic arc C) suspect terrane D) mid-oceanic ridge E) folded mountain range

Continents grow bigger as _______. A) accretionary wedges form at the margins B) gravitational collapse and spreading widens the craton C) mountain belts evolve along their margins D) uplift and block-faulting takes place E) isostacy lifts them up

Major mountain belts with higher mountain ranges tend to be geologically ___________ relative to those where the mountains are lower. A) the same age B) younger than C) random in age D) older than

Geologists regard most bodies of ultramafic rock as being _______. A) intrusions formed during the accumulation stage B) due to gravitational collapse and spreading C) due to lithospheric delamination D) areas left by block faulting and uplift E) mantle material faulted into the crust during orogeny

The present ________ represent rejuvenation following uplift in Late Tertiary time. A) Appalachian Mountains B) Alps C) Himalayan Mountains D) Ural Mountains E) Sierra Nevada Mountains

The system approach regards mountains as the products of three closely interdependent components. Which of the following is not one of those components? A) plate tectonics B) meteor impacts C) climate D) erosion

Of the two major mountain belts in North America, the _______ are in the West. A) Urals B) Himalyan C) Appalachians D) North American Cordillera E) Andes

A(n) __________ is an episode of intense deformation of the rocks of a region. A) isostatic adjustment B) geosyncline C) orogeny D) buoyancy event E) basin to dome event

The Grand Canyon, Ozark dome, Black Hills, and Adirondacks expose ________. A) a fold and thrust belt B) ophiolites C) a Precambrian basement D) an ancient magmatic arc E) the result of delamination

Most of the _____ of the United States has/have a very thin blanket - only 1000 to 2000 meters - of sedimentary rock layers. A) craton B) Gulf Coast C) Rocky Mountain region D) Oregon-Washington coast E) Blue Ridge Mountains

According to the concept of ____, lighter less dense continental crust "floats" higher on the mantle than denser oceanic crust. A) delamination B) gravitational collapse C) geosynclines D) block faulting E) isostacy

A(n) _________ mountain range, such as the Basin and Range and Tetons, implies a horizontal extension strain. A) fault block B) erosional C) volcanic D) fold E) strike-slip.