Ch9 – Continental Tectonics And + Test Questions & Answers

1.

A special type of graben that develops during early rifting of new plate boundaries is called a

A)

hot spot.

B)

rift valley.

C)

triple junction.

D)

composite rift.

2.

The center of a triple junction with a failed arm is at the

A)

Persian Gulf.

B)

Afar Triangle.

C)

East African rift valley.

D)

San Andreas fault in California.

3.

A failed rift is oriented roughly

A)

perpendicular to a deep valley that holds a very large river.

B)

parallel to the long dimension of the newly opened ocean.

C)

parallel to the rifted margin of the broken continent.

D)

perpendicular to the rifted margin of the broken continent.

4.

The age of eastern African rift valleys is

A)

Cenozoic.

B)

Mesozoic.

C)

Paleozoic.

D)

Precambrian.

5.

Marine sediment lying above evaporate deposits beneath the Red Sea shows us that the

A)

Red Sea is slowing drying up.

B)

Red Sea is the failed arm of a triple junction.

C)

Indian Ocean once covered a large part of northern Africa.

D)

Indian Ocean has only recently gained access to the widening Red Sea.

6.

Select the characteristic below that is NOT consistent with continental rifting.

A)

Mafic and felsic igneous rocks, including dikes and sills.

B)

Thick sedimentary sequences within fault block basins, including lake deposits.

C)

Multiple thrust faults and other compression features.

D)

Coarse terrestrial deposits and evaporites overlain by oceanic sediments.

7.

Typically, active margins are characterized by

A)

subsidence below sea level and tectonic inactivity.

B)

tectonic deformation and igneous activity.

C)

great thicknesses of undisturbed sediment.

D)

continuous subsidence under the weight of added sediment.

8.

Synclines are characterized by layers that

A)

are concave upward.

B)

are concave downward.

C)

include a high proportion of shales and sandstones.

D)

include a high proportion of sandstones and limestones.

9.

On any given tilted bed, strike and dip are

A)

parallel to one another.

B)

perpendicular to one another.

C)

at some large angle to one another, but not 90 degrees (greater than 90 degrees).

D)

at some small angle to one another, but not 90 degrees (less than 90 degrees).

10.

__________ is the line of intersection between the axial plane and the beds of folded rock.

A)

Axis of a fold

B)

Regional strike

C)

Axial plane

D)

Regional dip

11.

__________ is the process of mountain building.

A)

Suturing

B)

Orogenesis

C)

Ophiolite

D)

Subduction

12.

Ophiolites consist of

A)

sandstones that were turbidites.

B)

evaporites overlain by marine sediments.

C)

ultramafic rocks including pillow basalts.

D)

deep-sea deposits of black shale and chert.

13.

With respect to a typical metamorphic belt, a fold-and-thrust belt lies

A)

toward the continental interior, near the boundary with the foreland basin.

B)

on the oceanic side, near the boundary with the subduction zone.

C)

directly below the metamorphic belt, within the deeper crust.

D)

directly above, in rocks thrust over the metamorphic belt.

14.

The downwarping of the lithosphere beneath an actively forming mountain chain continues for some distance beyond the fold-and-thrust belt, thus producing a(n)

A)

gravity spreading.

B)

thick section of flysch.

C)

thin section of molasse.

D)

elongate foreland basin.

15.

Sometimes a thick body of molasse is referred to as a(n)

A)

structural basin.

B)

elongate foreland basin.

C)

ancient mountain belt.

D)

clastic wedge.

16.

A change in the angle of plate subduction usually reflects a change in the

A)

rate of oceanic sedimentation on the plate.

B)

rate of movement of the crustal plate.

C)

volume of melted material rising to the surface over time.

D)

increasing height of a volcanic mountain chain.

17.

The __________ formed during Cretaceous and Paleogene when Iberia collided with Eurasia.

A)

Andes

B)

Rockies

C)

Pyrenees

D)

Appalachians

18.

The brief time span during Cretaceous when this mountain range formed was NOT long enough to produce any igneous rocks.

A)

Appalachians

B)

Black Hills

C)

PyrennesPyrenees

D)

Andes

19.

During __________, a long seaway occupied the foreland basin to the east of the Andes Mountains.

A)

Paleocene

B)

Miocene

C)

Oligocene

D)

Eocene

20.

An ophiolite is made up of part of the

A)

sedimentary layer on an oceanic plate.

B)

mafic seafloor of the oceanic plate.

C)

sedimentary layer on a continental plate.

D)

volcanic basalts on a continental plate.

21.

The onset of deposition of molasse sediments in the foreland basin indicates that

A)

accumulation of sediment has pushed away the foreland basin sea.

B)

the mountain chain has worn down and isostatic uplift has begun.

C)

the moving continent has stalled at the subduction zone.

D)

a deep foreland basin is starting to form and the sea has filled the basin.

22.

The present process of mountain- building in the Andes began during

A)

Cenozoic.

B)

Mesozoic.

C)

Paleozoic.

D)

Precambrian.

23.

In eastern South America (Brazil), at shallow depths underlying the sedimentary deposits of the Amazon River, there are

A)

sedimentary deposits of an inland sea.

B)

igneous rocks of the Andes volcanoes.

C)

thick sedimentary deposits of flysch and molasse.

D)

Atlantic sea floor sediments such as shale and chert.

24.

_________ is the name given to microcontinents that have attached themselves to larger landmasses, especially the western part of North America.

A)

Exotic terranes

B)

Structural basins

C)

Structural domes

D)

Thrust belts

25.

The Black Hills of South Dakota are an example of a

A)

metamorphic belt.

B)

fault zone.

C)

structural dome.

D)

structural basin.

26.

The Appalachian Basin is to the Appalachian Mountains as the Williston Basin is to the

A)

Black Hills.

B)

Rocky Mountains.

C)

Nemaha Ridge.

D)

Nashville Dome.

27.

Stretching or weakening of the crust (without rifting) as North America moved over a hot spot may have caused the development of the

A)

Appalachian and Anadarko basins.

B)

Michigan and Permian basins.

C)

Cincinnati and Nashville domes.

D)

Black Hills and Rocky Mountains.

28.

Deep-seated crustal faults dating from Proterozoic may have caused powerful earthquakes with epicenters in __________ during 1811–1812.

A)

Michigan

B)

Missouri

C)

Mississippi

D)

Montana

29.

Two of the westernmost structural basins of the United States are named

A)

Williston and Permian.

B)

Anadarko and Forest City.

C)

Michigan and Illinois.

D)

Appalachian and Michigan.

30.

The oldest rocks of the Michigan Basin are __________, and these are found at the Earth's surface __________.

A)

Pennsylvania; on the outer edges of the basin.

B)

Jurassic; at the center of the basin

C)

Precambrian; on the outer edges of the basin

D)

Silurian; at the center of the basin