6.4

Geologic activity that takes place within a plate rather than at plate boundaries is known as __________ activity.

intro plate

Which feature could form at a divergent plate boundary?

Rift Valley

A region where the phenomenon described in question 3 occurs often is called a(n) __________.

continental ark

result of divergent plate boundaries that occur within a continent

continental rifting

Seafloor spreading occurs because of

convection cells in the mantle.

edge where two plates move toward each other

convergent plate boundary

A large chunk of lithosphere that can move over Earth's surface is called a(n)

plate

The edge where two tectonic plates meet is called a(n)

plate boundary

The movement of plates over Earth's surface is called __________

plate tectonics

At a convergent plate boundary between oceanic and continental crust, the oceanic crust always plunges beneath the continental crust because oceanic crust is

denser.

edge where two plates move away from each other

divergent plate boundary

point on the Earth's surface directly above the place where an earthquake occurs

epicenter

Earthquakes occur only at transform plate boundaries.

false

Hotspot magma rarely penetrates oceanic crust.

false

Mid-ocean ridges occur at convergent plate boundaries.

false

The Atlantic Ocean currently is shrinking because of plate tectonics.

false

__________ occurs when an oceanic plate plunges beneath a continental plate at a convergent plate boundary.

subduction occurs

Some of the largest mountains in the world, including the Himalayas, occur where

two continental plates converge.

Earthquake epicenters outline the edges of tectonic plates.

True

Most geologic activity takes place

at plate boundaries.

large body of intrusive igneous rock at the edge of a subducting plate

batholith

Nearly all tectonic plates consist of

both oceanic and continental crust.

Each year, tectonic plates move a few

centimeters.

A line of volcanoes that forms where two oceanic plates converge is called a(n) __________.

island ark

line of coastal volcanic islands at the edge of a subducting plate

island ark

edge where two plates slip past each other

transform plate boundary

Convection cells in the mantle rise at deep-sea trenches.

true

Hotspot volcanoes form in a line as crust moves over a mantle plume.

true

Supercontinents form and break up in a cycle.

true

The Appalachian Mountains formed at a convergent plate boundary as Pangaea came together.

true

Volcanoes are unlikely where two continental plates converge.

true