Geology

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A _____ plate boundary is where plates are moving away from each other.

divergent

Most of the evidence for magnetic reversals comes from lava flows on the continents.

true

Seismic waves travel faster in oceanic crust than in continental crust.

true

Submarine canyons are erosional features.

true

Terrigineous sediment is sediment derived from the land.

true

The Moho separates the crust from the mantle.

true

The San Andreas Fault is a transform fault.

true

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

true

The boundary between the core and the mantle is marked by great changes in ____.

Seismic velocity, density, and temperature are all correct.

A tsunami has a small wave height, travels rapidly, and is not noticed by people in boats.

True

Convergent boundaries, due to their geometry, are the sites of the largest earthquakes on Earth.

True

Deeply buried rock that is hot and under pressure can deform like taffy or putty.

True

Earth's lithosphere is made up of the uppermost part of the mantle and crust.

True

Geology uses the scientific method to explain natural aspects of the Earth.

True

Rocks brought to the earth's surface by internal processes are worn down, and eroded by surficial processes.

True

A deviation from average reading is called a(n) ____.

anomaly

Many guyots and seamounts are aligned in chains (for example the Hawaiian Islands and Emperor seamounts) that form major _____.

aseismic ridges

The ____ is a low velocity seismic zone.

asthenosphere

The ____ is soft and therefore flows more readily than the underlying mantle.

asthenosphere

_____ parallel the shore, but are separated from it by wide, deep lagoons.

barrier reefs

The _____ crust of the sea floor is covered in many places with layers of sediment.

basalt

The P-wave shadow zone can be explained by the refraction of P-waves at the ___.

core mantle boundary

The concept of isostatic adjustment implies that all mountains extend to the same depth in the mantle.

false

The deepest places on Earth, more than 11 km below sea level, are the abyssal plains.

false

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

false

Abyssal fans are made up of _____ sediment that has moved down submarine canyons

land derived

One widely accepted hypothesis is that the Earth's magnetic field is created by electric currents within the ______.

liquid outer core

Oceanic trenches are marked by _______.

low heat flow

The downward plunge of cold rock at convergent boundaries accounts for the existence of _____.

oceanic trenches

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

true

A cavity or body of low-density material causes a _____ pull on a gravity meter relative to average crust.

weaker

Most geologists think that the flat summits of seamounts ___.

were eroded flat by wave action

The North American plate is moving ____.

west

Sea-floor spreading implies that sea-floor rocks should be ______________.

youngest on the crest of mid ocean ridges

Water depth increases over a continental shelf to the outer edge depth of _____ to ____ meters.

100/200

The magnetic poles are displaced about ______ degrees from the geographic poles.

11.5

A gravity reading lower than the normal regional gravity indicates that a region is ____.

being held down

The crust and upper mantle form the ____.

lithosphere

Measured rates of sea-floor spreading range from ______ cm/year.

1 to 24

Seismic surveys of the sea have shown the oceanic crust to be divided into _______ major layers.

3

The best geologic data currently available indicates that Earth is approximately ___ years old.

4,550,000,000

Fossil evidence indicates that complex life forms, capable of generating easily fossilized hard parts like shells or bones, have existed in abundance on Earth since approximately ___ years ago.

544 million

Oceans cover _____ percent of the Earth's surface.

70

In the early 1900s the German meteorologist _____ made a strong case for continental drift.

Alfred Wegener

____ volcanoes can be found along subducting plate boundaries.

Andesitic

Because _____ can be accurately calculated, the size and shape of the core can be determined.

P wave paths

Divergent plate boundaries can occur where spreading occurs under a continent, for example ___.

the red sea

Hot mantle rock rising slowly by convection under parts of the ocean explains ____.

the unexpectedly high heat flow under the oceans

A _____ is a scientific concept that has been tested and is in all likelihood true.

theory

A _____, by scientists definition, is something that has been overwhelmingly verified.

theory

Continental crust is ___ relative to oceanic crust.

thicker

Oceanic crust is _____ continental crust.

thinner than

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.

transform

Turbidity currents flow down the continental slope until they come to rest on ___.

the abyssal plain

While the reserves of petroleum hydrocarbons within the United States are limited, other geologic resources (iron, aluminum, copper, and tin) are available in great abundance.

False

Plate motion can be measured directly using ____.

GPS

Pangea initially separated into two parts, the southern part is called ____.

Gondwanaland

The Earth can be considered as interrelated systems or spheres.

True

The Earth is about 4.6 billion years old.

True

The North American Plate is all on one plate.

True

The mantle is the most voluminous of Earth's three major concentric zones.

True

Understanding geology can help us lessen or prevent damage to the environment.

True

We depend on geologists for the raw materials we need for survival

True

A ______ is a huge ocean wave usually caused by a displacement of the sea floor and commonly associated with massive earthquakes.

Tsunami

One kind of convergent plate boundary is ____.

continent-continent convergence

The two major types of crust are oceanic crust and __.

continental crust

____ is the idea that continents move freely over Earth's surface, changing their positions relative to one another.

continental drift

The ____ is a shallow submarine platform at the edge of a continent.

continental shelf

The continental shelf is part of the ____.

continents

_____ currents are bottom currents that flows parallel to the slopes of the continental margin.

contour

A ______ is a bottom flowing current that flows parallel to the slopes of the continental margins.

contour current

Hess's original hypothesis was that sea-floor spreading is driven by deep mantle ____.

convection

_____ is a circulation pattern in which low-density material rises and high-density material sinks.

convection

A _______ boundary occurs where plates move towards one another.

convergent

This type of plate boundary the two plates can consist of ocean-ocean, ocean-continent, or continent-continent crust.

convergent

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

convergent boundaries

Iron-nickel meteorites are an important source of information regarding the composition of Earth's ______.

core

Listed from Earth's center outward, the three concentric zones of Earth are the __.

core, mantle, crust

The _______ collectively make up the lithosphere.

crust and the uppermost part of the mantle

The rise of the crust after removal of ice is called ____.

crustal rebound

As lava cools below the _____ point, a record of the Earth's magnetic field is permanently trapped in the rock.

curie

The ____ is the transition zone at the core-mantle boundary.

d layer

Heat flow ______ the crest of the mid-oceanic ridges.

decreases away from

The _____ of old seafloor takes place at convergent boundaries.

destruction

The Rift Valley in East Africa is an example of a _____.

diverging plate boundary

In a passive continental margin, there is a lack of _______.

earthquakes , volcanos, and young mountain belts

A basic tool for indirectly studying the sea floor is the ____, which measures water depth.

echo sounder

Recently, geologists have been analyzing ____ generated by tidal friction, ocean waves, and storms to gain an even more detailed image of the crust and upper mantle.

energy waves

_______ takes place where moving water, ice, and wind loosen and remove material on the continents.

erosion

Most seamounts are ______.

extinct volcanoes

A region held down out of isostatic equilibrium produces a negative gravity anomaly.

false

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

false

All rocks and sediments of the sea floor are more than 3 billion years old.

false

All transform faults connect two ridge segments.

false

An oceanic trench is a deep narrow rift parallel to the crest of a mid-oceanic ridge.

false

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.

false

Continental slopes are often marked by lines of hot springs that precipitate metals.

false

Generally, seismic wave velocity decreases with depth.

false

Geologists think that the asthenosphere is molten.

false

Guyots and seamounts are scattered randomly on the sea floor.

false

Lithosphere is remarkably constant in thickness across ocean basins.

false

Most seamounts are active volcanoes.

false

Ophiolitic sediment is composed of wind-blown dust and microscopic skeletons that settle slowly to the sea floor.

false

Passive margins are found on the edges of most of the landmasses bordering the Pacific Ocean.

false

Pelagic sediment is sediment that settles slowly through the ocean water.

false

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

false

Suture zones in continents mark old sites of mantle plumes.

false

The Earth's core is made up of equal parts cobalt and iron.

false

The average density of the Earth is 2.7 gm/cm3.

false

When a ridge subsides sea level may rise.

false

Which of the following lifeforms appeared first in the geologic record?

fishes

_____ are major lines of weakness in Earth's crust that cross the mid-oceanic ridge at right angles.

fracture zones

Earthquakes, volcanic eruptions, landslides, floods, and tsunamis are all examples of:

geologic hazards

___ refer(s) to the scientific study of Earth.

geology

_____ is the branch of geology that applies physical laws and principles to study Earth.

geophysics

During extension in divergent plate boundaries a rift valley forms as a central ____.

graben

Turbidity currents are great masses of sediment-laden water that are pulled downhill by ____.

gravity

A ____ is a tool used to study the gravitational attraction between Earth and a mass within the instrument.

gravity meter

High _____ is usually an indication of a magma body or still-cooling pluton near the surface.

heat flow

The gradual loss of heat through the Earth's surface is called ___.

heat flow

Plumes form ______ that are related to areas of active volcanism such as Iceland, Yellowstone and Hawaii.

hot spots

Mid-oceanic ridges are often marked by lines of _____ that carry and precipitate metals.

hot springs

Rock deep within the Earth is _____ and ______.

hot/ heat flows out towards earth surface

Among other things, geologists are employed as __.

hydrogeologists, petroleum geologists, environmental geologist, marine geologist

The Earth's system that includes the oceans, rivers, lakes, and glaciers of the world is called the _______.

hydrosphere

After data have been analyzed, tentative explanations or solutions called _____ may be proposed.

hypothesis

A gravity meter registers _____ over ore bodies.

increased gravity

The continental shelves of the world are typically covered by relatively young sediments derived from ___________.

land

With the cementation of loose particles sediment becomes ______.

lithified

The ___ includes rocks of the crust and uppermost mantle.

lithosphere

The concept of plate tectonics regards the earth's ___ as broken into a number of ___ that are in motion relative to each other.

lithosphere/ plates

Magma heated by ocean-continent convergence may form a(n) _____ such as the Aleutian Islands.

magmatic arc

Marine geologists can predict the age of igneous rocks of the sea floor by measuring _____.

magnetic anomalies

A region of magnetic force, called the ______ surround Earth.

magnetic field

The _______ is the most voluminous of the Earth's three major concentric zones.

mantle

Evidence in support of continental drift includes ____.

matching of geologic patterns on continents, fit of continental margins, glacial striation patterns, and fossil distribution on different continents

Sedimentary rock that becomes deeply buried may be transformed by heat and pressure into _______ rock.

metamorphic

Shallow focus earthquakes on the sea floor are associated with ___.

mid ocean ridge crests

A divergent boundary on the sea floor is associated with ______.

mid oceanic ridges

Alternating positive and negative polarity magnetic anomalies in the crust form a stripe-like pattern parallel to _____.

mid oceanic ridges

Project FAMOUS used submersibles to study ______.

mid-ocean ridges

The boundary that separates the crust from the mantle is the ____.

mohorovicic discontinuity

The Earth's interior heat engine works because hot buoyant material deep within the Earth _______ while cold denser material _______.

moves upward/ moves downward

Eruptive activity at the summit of the Nevada del Ruiz volcano in Colombia in 1985 caused snow and ice to melt, generating a ___ that killed 23,000 people in the village of Armero.

mud flow

The Peru-Chile trench is moving over the ________ Plate as South America moves west.

nazca

The isotopic ages of Hawaiian Island basalts increase regularly to the ____.

northwest

Where a subducting plate slides beneath the lithosphere, melting takes place and a(n) ____ is created.

ocean trench

Earthquakes, volcanoes, Benioff seismic zones, and island arcs are all associated with this sea floor feature.

oceanic trench

Geologists' ideas about the composition of ocean crust are greatly influenced by the study of ____.

ophiolites

The study of ancient magnetic fields is called ____.

paleomagnetism

Wegener reassembled the continents to form the super continent _____.

pangea

At a pressure equivalent to a depth of 670 km the mineral olivine collapses to form ____.

perovskite

_____ are rounded masses of rock that form when molten lava erupts into cold water.

pillow lava

In plate tectonics, intense geologic activity occurs at ____.

plate boundaries

The basic idea of ______ is that the Earth's surface is divided into a few large plates that move slowly relative to one another.

plate tectonics

The apparent movement of the magnetic poles through geologic time is called _____.

polar wandering

Disintegration of rock at Earth's surface may be facilitated by water __.

present as vapor in the atmosphere, moving through near surface pores and fractures, frozen in glacier that is flowing over the surface, flowing on the surface in streams and as runoff

A ___ is a hot, turbulent mixture of expanding gases and volcanic ash that flows rapidly down the side of a volcano.

pyroclastic flow

The bending of seismic waves as they pass from one material to another is called seismic ____.

refraction

The rock record for tens of millions of years indicates that the Earth's magnetic field ____.

reverses polarity about every 500,000 years

The most common type of transform faults offset oceanic ____.

ridge crests

The crests of mid-oceanic ridges are associated with ____.

rift valleys

Harry Hess proposed that the _______.

sea floor moves

In this hypothesis the two sides of the mid-oceanic ridge are moving in opposite directions like slow conveyor belts.

sea floor spreading

The study of _____ rocks, sediment, and topography provided most of the information that led to the concept of plate tectonics.

seafloor

The product of the breakdown of surface rocks by weathering and erosion is __.

sediment

A(n) ___ may eventually be formed as layers of sediment are buried by subsequent layers of sediment.

sedimentary rock

Detailed images provided by _____ suggest that the mantle is heterogeneous, probably due to variations in temperature, composition, and density.

seismic reflection

_____ is the return of some of the energy of a seismic wave to the Earth's surface after it bounces off a rock boundary.

seismic reflection

This instrument works on essentially the same principles as echo sounder but can penetrate the bottom of the sea floor and provides more information.

seismic reflection profiler

One possible mechanism for plate tectonic drive is ____.

slab pull

Earth can be visualized as a giant machine driven by which of the following engines?

solar and internal

Earth's external heat engine is driven by __.

solar power

_____ are V-shaped valleys that run across continental shelves and down continental slopes.

submarine canyons

These machines can take geologists to many parts of the sea floor to observe, photograph, and sample rock and sediment.

submersibles

To understand geology one must understand how the solid Earth interacts with water, air, and living organisms. For this reason, it is useful to think of Earth as being part of a ____.

system

_______ are geological forces generated inside the Earth.

tectonic forces

___ indicates that the core of the Earth is a liquid.

the S wave shadow zone

The average temperature increase in the shallow crust (the geothermal gradient) is about ______ degrees C per kilometer.

25

Fossil evidence indicates that dinosaurs became extinct approximately ___ years ago.

65 million

______ proposed that the three types of coral reefs are related to each other by subsidence of a central volcanic island.

Charles Darwin

A transform plate boundary occurs where two plates converge.

False

After the opening of the North Slope in Alaska the U.S. stopped importing petroleum.

False

Most convergent plate boundaries coincide with the crests of submarine mountain ranges called mid-oceanic ridges.

False

Most deaths associated with volcanic eruptions are due to burns of lava flows.

False

Ocean - ocean plate convergence formed major mountain belts such as the Andes and Cascades.

False

Plate tectonics regards the lithosphere as divided into segments (plates) that are in horizontal motion.

False

Rocks formed at high temperatures and under high pressure deep within the Earth and pushed upward by tectonic force are stable in their new environment.

False

The abyssal plains are formed of _____.

Horizontal layers of sediment

_______ is an island on a mid-oceanic ridge.

Iceland

_______ is a balance or equilibrium of adjacent blocks of brittle crust floating on the upper mantle.

Isostasy

_____ predicts that the higher a mountain range extends above sea level the deeper it extends into the mantle.

Isostatic adjustment

What is the asthenosphere?

It is the zone of weakness in the mantle on which the lithosphere moves.

The _____ and the Alpine Fault of New Zealand are examples of transform plate boundaries.

San Andreas Fault of California

A hypothesis that passes repeated tests ultimately becomes __.

a theory

Thick deposits of sediment called _____ are found at the base of many submarine canyons.

abyssal fans

The continental rise typically ends at a(n) _______ at a depth of about 5 kilometers.

abyssal plain

The inner wall of a trench consists of a(n) _____ of thrust-faulted and folded marine sediment and pieces of oceanic crust.

accretionary wedge

Plates are known to be moving away from each other __.

across mid ocean ridges

A(n) _____ continental margin usually lacks a continental rise and an abyssal plain and is associated with convergent plate boundaries.

active

__________ is the name applied to hot springs on the seafloor where 350 degree Celsius metal-rich solutions are discharged into the cold waters of the ocean.

black smokers

The Himalayan Mountains are thought to have formed ____.

by continent-continent convergence

The San Andreas Fault is _________ in California.

transform fault

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

transform fault

Seismic P-waves _____ through continental crust relative to oceanic crust.

travel slower

A contour current is a bottom current that flows parallel to the slopes of the continental margin.

true

A gravity meter can be used to explore for metallic mineral deposits.

true

A rift valley runs down the crest of most mid-oceanic ridges.

true

Abyssal plains are the flattest features on Earth.

true

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

true

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

true

Atolls are circles of reefs that rim lagoons.

true

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

true

Geologists study the composition of the Earth's crust using deep drill holes.

true

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

true

Ocean water originated mainly from degassing of the Earth's interior.

true

Oceans cover more than 71% of the Earth's surface.

true

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

true

Seismic tomography uses earthquake waves and computers to study cross sections of the mantle.

true

The asthenosphere may be a partially melted crystal and liquid slush.

true

The average heat flow of the continents is the same as the average heat flow of the sea floor.

true

The composition of the upper mantle is the ultramafic rock peridotite.

true

The continental rise is a wedge of sediment that extends from the lower part of the continent slope to the deep-sea floor.

true

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

true

The force of gravity between two objects decreases as the square of the distance between the objects increases.

true

The greatest negative gravity anomalies in the world are found over oceanic trenches.

true

The island of Iceland appears to be an exposed section of the Atlantic mid-oceanic ridge.

true

The ocean became salty as water picked up chlorine from volcanic gases and sodium and magnesium from weathering of minerals at the Earth's surface.

true

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

true

The presence of an S-wave shadow zone implies that the Earth's core is liquid.

true

The rise of the surface of the crust after removal of glacial ice is known as isostatic rebound.

true

The way that P-waves are refracted within the core suggests that there is a solid inner core.

true

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

true

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

true

The Grand Banks cable breaks of 1929 are interpreted to be the result of earthquake-caused ____.

turbidity currents

A(n) _____ is a great mass of sediment-laden water that is pulled downward by gravity along the continental slope.

turbidity flow

The upper mantle consists of _______.

ultramafic rocks

The head of large plumes that form "hot spots" may cause uplift and ____.

vast fields of flood basalt

_______ proposed an explanation for magnetic anomalies.

vine and matthews

Plate tectonics is a unifying idea that helps explain where and why there are ___ on Earth.

volcanoes, earthquakes, mountain belts, oceanic ridges and trenches


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