Geology Ch. 2 Quiz

2 centimeters per year

A typical rate of seafloor spreading in the Atlantic Ocean is ________.

hot spot

A very long-lived magma source located deep in the mantle is called a ________.

There is no oceanic crust older than 180 million years old

After World War II, what was discovered about the ocean floor?

continental crust

Australia is composed of relatively old and thick

The continents and ocean basins of Earth had always had fixed locations

Before the introduction of the continental drift hypothesis, what view did scientists have of Earth's continents and ocean basins?

subduction zones along convergent plate boundaries

Cooler, older, oceanic lithosphere sinks into the mantle at ________.

Pacific

Deep-oceanic trenches are most abundant around the rim of the ________ ocean basin.

glaciation

Evidence of ________ having affecting landmasses currently in subtropical and tropical regions provides evidence supporting Wegener's continental drift hypothesis.

an ocean

The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?

divergent boundaries by submarine eruptions and intrusions of basaltic magma

New oceanic crust and lithosphere are formed at ________.

hot spot

Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a

The tectonic plates are separating to the NW and SE

The Mid-Atlantic Ridge crosses through Iceland. Physical features such as tensional fractures and cinder cone volcanoes are all aligned NE-SW. What does this indicate about the directions the tectonic plates are moving?

northward movement of India into Eurasia

The ________ is an example of an active, continent-continent collision.

youngest rocks near the center of Iceland, oldest rocks near the East and West Shores

The rocks that make up Iceland have a very specific age pattern related to the presence of the Mid-Atlantic Ridge. What is this age progression?

seafloor spreading

The slowly increasing distance between South America and Africa is due to

the collision of India with Asia

What caused the formation of the Himalayas?

Older and denser oceanic lithosphere is constantly subducting into the mantle at a rate equal to new lithosphere creation at divergent boundaries.

What causes the rate of lithosphere destruction to be roughly equivalent to the rate of lithosphere creation?

new oceanic lithosphere

What forms at divergent plate boundaries?

Very few plate boundaries follow the edges of continents.

What is the relationship between continent edges and plate boundaries?

a supercontinent that began to break apart about 200 million years ago

What was Pangaea?

the single ocean that existed after the Pangaean supercontinent formed

What was Panthalassa?

a piece of the Panthalassa Ocean that existed after the Pangaean supercontinent formed

What was the Tethys Sea?

Laurasia and Gondwanaland

What were the names of the two smaller super continents that formed when Pangaea broke apart?

seafloor crust

_______________ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

divergent

characterized by seafloor spreading

convergent

characterized by volcanic arcs and deep-ocean trenches

sedimentary rock

layered ______________ exposed by erosion can be seen when looking at the Grand Canyon in the United States.

divergent

Pull-apart rift zones are generally associated with a ________ plate boundary.

Violent eruptions send ash and cinders high into the air. Meltwater can result in massive jökulhlaups.

Some of Iceland's volcanoes are covered by large glaciers. What are some of the hazards that may occur if one of those glacier-covered volcanoes erupted?

Cooling lava contracts, creating fractures.

Structures such as columnar joints are found near Gullfoss in the Reykjanes Peninsula. How were these structures created?

divergent

plates are moving apart from one another

transform

plates are sliding past one another horizontally

divergent

the Mid-Atlantic Ridge

transform

the San Andreas fault

transform

this boundary is normally devoid of volcanism

convergent

where lithosphere is sinking into the mantle

convergent

where subduction zones occur

the Pacific plate, the Nazca plate, and the Australian-Indian plate

which three lithospheric plates are moving fastest?

North America

Geologists from which continent were initially the least receptive to the continental drift hypothesis?

A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity

How are normal polarity and reverse polarity of Earth's magnetic field different?

Plates move toward one another.

How do plates move at convergent plate boundaries?

Plates move apart

How do plates move at divergent plate boundaries?

Plates slide past one another

How do plates move at transform plate boundaries?

every 100,000 to several million years

How often does the Earth's magnetic field switch polarity?

Iceland is receiving magma from a mantle plume. Iceland is receiving magma from decompression melting along the Mid-Atlantic Ridge.

Iceland is unique along the Mid-Atlantic Ridge because it is the only part of the ridge that is elevated above sea level. Why might this be the case?

A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.

In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?

convergent plate boundaries divergent plate boundaries

In general, where do earthquakes AND volcanic eruptions occur?

on the overriding plate, away form the convergent boundary

In general, where do volcanoes form in subduction zones?

Alfred Wegener

In the early part of the twentieth century, ________ argued forcefully for continental drift.

identify a mechanism capable of moving continents

The continental drift hypothesis was rejected primarily because Alfred Wegener could not ________.

fault

The earthquakes that occur in Southern California generally occur along a ____________

subduction

The extremely deep ocean Marianas Trench is a result of

Pangaea

The late Paleozoic supercontinent is known as ________

it is hot, and therefore less dense than the cooler rocks surrounding it

The main reason for the elevated position of the oceanic ridge is because ________

on both sides of the mid-ocean ridge

Where would you expect to see alternating bands of rock with different magnetic polarities?

export of heat from deep in the mantle to the top of the asthenosphere

Which of the following energy sources is thought to drive the lateral motions of Earth's lithospheric plates?

Magma wells up at the center of the ridge, which pushes the old seafloor apart as new seafloor is created.

Which of the following scenarios best describes the activity present along the Mid-Atlantic Ridge?

Earth's magnetic field switches polarity at irregular time intervals

Which of the following statements about Earth's magnetic field is most accurate?

Most tectonic plates contain both oceanic and continental lithosphere.

Which of the following statements about tectonic plates is true?

pacific plate

Which of the plates listed below is the largest plate on the Earth?

They are fed by a long-lived hot spot below the Pacific lithospheric plate.

Which one of the following most accurately describes the volcanoes of the Hawaiian Islands?

Gondwanaland

Which supercontinent contained Africa and South America?

divergent

Which type of plate boundary is most closely associated with the formation of new ocean floor?

divergent boundary

Which type of plate boundary occurs where two plates move apart, resulting in upwelling and partial melting of hot material from the mantle?

Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.

Why are volcanoes NOT found at transform boundaries?

The oceanic lithosphere is thinner and denser than the continental lithosphere, which is thicker and less dense

Why does oceanic lithosphere subduct under continental lithosphere, whereas continental lithosphere does not subduct under oceanic lithosphere?