Quiz 19: Plate Tectonics

Pangea initially separated into two parts, a northern supercontinent, and a southern supercontinent.

Continental drift is the hypothesis that the sea floor forms at the crest of the mid-oceanic ridge, then moves horizontally away from the ridge crest.

Wegener's theory of continental drift proposed that the continents plowed through oceanic crust.

Continental drift incorporated sea floor spreading into the new concept of plate tectonics.

The Vine-Matthews hypothesis provided a means to measure the rate of sea-floor spreading.

All transform faults connect two ridge segments.

The asthenosphere is a mantle zone of low seismic wave velocity that behaves in a ductile manner.

As a descending plate reaches depths of about 100 km, magma is generated in the overlying asthenosphere.

The portion of a fracture zone between two offset portions of a ridge crest is called a transform fault.

Suture zones in continents mark old sites of mantle plumes.

A tectonic plate is always made up of a combination of continental and oceanic crust.

Magma that is created by ocean-continent convergence forms either island arcs or belts of igneous activity on the edges of continents.

Recent studies using seismic tomography indicates that whole mantle convection is the best model.

An island arc is a string of volcanoes parallel to the oceanic trench

Young mountain belts, with their associated igneous intrusions, metamorphism, and fold-thrust belts, form at convergent boundaries.

Lithosphere is remarkably constant in thickness across ocean basins.

When a ridge subsides sea level may rise.

The San Andreas Fault is a transform fault.

The downward plunge of cold lithosphere accounts for the existence of oceanic trenches as well as their low heat flow.

Wegener reassembled the modern continents to form the giant super continent of Gondwanaland.

In plate tectonics, intense geologic activity occurs at ____. A) plate boundaries B) ocean floor C) continental interiors D) along coastlines E) along mountain ranges

____ is the idea that continents move freely over Earth's surface, changing their positions relative to one another. A) Plate tectonics B) Sea floor spreading C) Continental drift D) Continental collisions E) Plate spreading

In this hypothesis the two sides of the mid-oceanic ridge are moving in opposite directions like slow conveyor belts. A) plate tectonics B) sea floor spreading C) continental drift D) continental collisions E) plate spreading

A _____ plate boundary is where plates are moving away from each other. A) convergent B) shear C) transform D) divergent E) transverse

The portion of a fracture zone between two offset portions of ridge crest is called a ____. A) normal fault B) strike-slip fault C) convergence zone D) Benioff zone E) transform fault

During extension in divergent plate boundaries a rift valley forms as a central ____. A) horst B) strike-slip fault C) graben D) mountain range E) subduction zone

These plate boundaries are marked by shallow-focus earthquakes in a narrow zone for a single fault or in a broad zone for a group of parallel faults. A) divergent B) transform C) ocean-continent convergence D) subduction E) ocean-ocean convergence

This type of plate boundary the two plates can consist of ocean-ocean, ocean-continent, or continent-continent crust. A) divergent B) strike-slip C) convergent D) transform E) transverse

The inner wall of a trench consists of a(n) _____ of thrust-faulted and folded marine sediment and pieces of oceanic crust. A) accretionary wedge B) subduction wedge C) large amount of sea D) active volcano consisting E) a gap

____ volcanoes can be found along subducting plate boundaries. A) Shield B) Cinder cone C) Andesitic D) Basaltic E) Pegmatitic

Hess's original hypothesis was that sea-floor spreading is driven by deep mantle ____. A) contraction B) spreading centers C) convergent boundaries D) transform faults E) convection

Harry Hess proposed that the _______. A) sea floor moves B) continents drift C) magnetic field reverses D) magnetic poles wander E) the core is liquid

Wegener reassembled the continents to form the super continent _____. A) Asia B) Pangea C) Laurasia D) Gondwanaland E) Madagascar

One possible mechanism for plate tectonic drive is ____. A) meteor impacts B) earthquake energy C) slab pull D) gravity sliding E) Benioff drive

Sea-floor spreading implies that sea-floor rocks should be ______________. A) the same age throughout B) youngest on the crest of mid-ocean ridges C) younger as water become colder D) younger toward the trench E) youngest on the continental shelf

Measured rates of sea-floor spreading range from ______ cm/year. A) 0.1 to 1 B) 100 to 1000 C) 1000 to 10,000 D) 1 to 24 E) 0.01 to 0.1

Marine geologists can predict the age of igneous rocks of the sea floor by measuring _____. A) the percent of iron-rich minerals in the rock B) their grain size C) the velocity of earthquake waves D) their density E) magnetic anomalies

The downward plunge of cold rock at convergent boundaries accounts for the existence of _____. A) continental shelves B) submarine hot springs C) oceanic trenches D) the Earth's core E) the abyssal plains

The Rift Valley in East Africa is an example of a _____. A) diverging plate boundary B) converging plate boundary C) transform plate boundary D) back arc spreading center E) continental rise

One kind of convergent plate boundary is ____. A) rift valley convergence B) continent-continent convergence C) transform convergence D) subduction zone convergence

The ___ includes rocks of the crust and uppermost mantle. A) true ocean basin B) asthenosphere C) lithosphere D) ophiolites E) Moho

In the early 1900s the German meteorologist _____ made a strong case for continental drift. A) Charles Plummer B) George Bush C) Ben Franklin D) Alfred Wegener E) Diane Carlson

The Himalayan Mountains are thought to have formed ____. A) by continent-ocean convergence B) by ocean-ocean convergence C) by continent-continent convergence D) at a spreading center E) at a transform fault

Plumes form ______ that are related to areas of active volcanism such as Iceland, Yellowstone and Hawaii. A) converging plate boundaries B) trenches C) aseismic ridges D) failed rifts E) hot spots

The head of large plumes that form "hot spots" may cause uplift and ____. A) andesitic volcanoes B) transform faults C) vast fields of flood basalt D) spreading centers E) subduction zones

The isotopic ages of Hawaiian Island basalts increase regularly to the ____. A) northwest B) east C) north D) south E) northeast

A divergent boundary on the sea floor is associated with ______. A) submarine trenches B) mid-oceanic ridges C) transform faults D) aseismic ridges E) guyots

The San Andreas Fault is _________ in California. A) a normal fault B) an oblique fault C) a transform fault D) a thrust fault E) a reverse fault

_______ proposed an explanation for magnetic anomalies. A) Charles Plummer B) Harry Hess C) Alfred Wegener D) Vine and Matthews E) Diane Carlson

The most common type of transform faults offset oceanic ____. A) abyssal plains B) microcontinents C) continental shelves D) trenches E) ridge crests

Divergent plate boundaries can occur where spreading occurs under a continent, for example ___. A) the Red Sea B) the Himalayan Mountains C) the Alps D) the Gulf of Mexico E) the Mediterranean Sea

Plate motion can be measured directly using ____. A) FBI B) GPS C) USGS D) NOAA E) GIS

The Peru-Chile trench is moving over the ________ Plate as South America moves west. A) North American B) Australian C) Nazca D) South American E) Antarctic

Magma heated by ocean-continent convergence may form a(n) _____ such as the Aleutian Islands. A) mantle diapir B) convection uplift C) abyssal plain D) magmatic arc E) hot spot

The apparent movement of the magnetic poles through geologic time is called _____. A) mantle plume motion B) polar drift C) sea-floor spreading D) continental drift E) polar wandering

Evidence in support of continental drift includes ____. A) glacial striation patterns B) fossil distribution on different continents C) fit of continental margins D) matching of geologic patterns on continents E) all of the choices are correct

Young mountain belts with their associated igneous intrusions, metamorphism, and fold-thrust belts form at _______. A) divergent boundaries B) continental rifts C) transform fault boundaries D) convergent boundaries E) hot spots

Pangea initially separated into two parts, the southern part is called ____. A) Rodinia B) Laurasia C) Panthallasia D) Gondwanaland E) Atlantis

Alternating positive and negative polarity magnetic anomalies in the crust form a stripe-like pattern parallel to _____. A) lines of longitude B) the equator C) continental margins D) aseismic ridges E) mid-oceanic ridges

The basic idea of ______ is that the Earth's surface is divided into a few large plates that move slowly relative to one another. A) continental drift B) sea floor spreading C) mantle plumes D) plate tectonics E) isostasy