GLG 111 - Quiz 4 & 5

Movement of plates away from each other at divergent boundaries typically shows which of the following average velocities?

5 cm per year

A continental volcanic arc is formed when which of the following conditions exists?

A piece of oceanic crust is subducted below continental crust.

Which of the following statements is part of the continental drift hypothesis?

A single supercontinent consisting of all Earth's landmasses once existed. The continents of South America and Africa fit together like pieces of a jigsaw puzzle.

Which of the following processes can be observed at the margins of lithospheric plates?

All of the responses are correct.

Although new crust is being formed at divergent boundaries, Earth remains the same size. Which of the following statements provides the best reason for this?

An equal volume of crust is being consumed at convergent boundaries.

Australia is composed of old and thick

Continental crust

In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?

Due to tectonic activity, rocks on the ocean floor are continually recycled.

Which of the following locations is a modern-day example of an active continental rift?

East Africa and the Red Sea

What happens to the lithosphere at transform plate boundaries?

Lithosphere is neither destroyed nor created, simply maintained or conserved.

Which of the following statements about divergent boundaries is true?

New ocean crust is created at a divergent boundary.

Which of the following statements regarding transform plate boundaries is not correct? Transform plate boundaries connect two segments of the oceanic ridge system. Earthquakes are a common occurrence along transform plate boundaries. At transform plate boundaries, adjacent lithospheric plates slide past each other horizontally. New oceanic crust is formed at transform plate boundaries. Transform plate boundaries can occur within continental crust.

New oceanic crust is formed at transform plate boundaries.

Which of the following regions was not part of the large Southern Hemisphere continent of Gondwana?

North America

At a divergent boundary, what is the relative motion of the plates on each side of the boundary?

The plates move away from each other.

At a convergent boundary, what is the relative motion of plates on each side of the boundary?

The plates move toward each other.

When moving away from a divergent boundary in either direction, which of the following statements is true?

The rocks increase in age.

As oceanic crust is subducted, it melts, forming a body of magma. When this magma rises and interacts with the overlying continental crust, what change occurs in the composition of the magma?

The silica content of the magma increases.

The formation of the Himalaya and the Tibetan Plateau was caused by which of the following events?

There was a collision of two pieces of continental crust at a subduction zone

During the breakup of Pangaea, volcanic island arc systems may have formed that no longer exist. What likely happened to these arcs?

They may have been accreted onto continents after their formation.

Why are volcanoes NOT found at transform boundaries?

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

Which of the following techniques can be used to recreate the configuration of supercontinents that existed before Pangaea?

apparently wandering polar paths

What geologic process initiated the breakup of Pangaea approximately 165 million years ago?

continental rifting

Which of the following processes drive plate tectonics?

convection subduction

What are the three categories of plate boundaries?

convergent divergent transform

In general, where do earthquakes AND volcanic eruptions occur?

convergent plate boundaries divergent plate boundaries

The earthquakes that occur in Southern California generally occur above a

fault

How do plates move at divergent plate boundaries?

Plates move apart.

How do plates move at convergent plate boundaries?

Plates move toward one another.

How do plates move at transform plate boundaries?

Plates slide past one another.

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

Seafloor crust

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

Seafloor spreading

Layered exposed by erosion can be seen when looking at the Grand Canyon in the United States

Sedimentary rock

The extremely deep ocean Marianas Trench is a result of

Subduction

What forms at divergent plate boundaries?

new oceanic lithosphere

In general, where do volcanoes form in subduction zones?

on the overriding plate, away form the convergent boundary

The occurrence of stream channels that have been offset along a transform fault are indicative of which of the following conditions?

opposite sides of the fault have shifted horizontally

What type of stress is most directly associated with transform faults?

shear stress

Which of the following features is considered a destructive plate margin?

subduction zone

Which of the following lithospheric plates is not included among the seven largest?

the Philippine plate

When oceanic and continental crust collide at a subduction zone, one plate is forced under the other. The angle at which the subducting plate descends is due to which of the following factors?

the age of the plate being subducted the density of the plate being subducted

Earth's lithospheric plates are composed of crust and which of the following layers?

the outermost portion of the mantle

Which of the following geologic processes and/or phenomena is not found at transform plate boundaries?

volcanoes

As oceanic crust is subducted below continental crust, which of the following factors most directly drives the melting that will fuel volcanoes at the surface?

water

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

Hot spot

Since the breakup of Pangaea approximately 165 million years ago, a new supercontinent cycle has begun with the collision of which of the following continents?

India and Asia

When oceanic crust is subducted beneath continental crust, partial melting can occur. Which of the following best explains why the resultant magma rises through the crust toward the surface?

The magma is less dense than the surrounding solid rock

Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring. What type of plate boundary is this?

a convergent plate boundary

Continued movement of the continental crust on the west side of the San Andreas fault could result in which of the following features?

an island

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?

an ocean