chapter 17

Approximately how long did the Gauss epoch last?

1 million years

convergent

A __________ boundary occurs when two tectonic plates collide with each other.

transform

A __________ boundary occurs when two tectonic plates slide past each other.

convergent boundaries

A boundary where two plates come together is a transform boundary

rift valley

A divergent boundary within a continent forms a trench

divergent

At a __________ plate boundary, new crust is created as two or more plates pull away from each other.

How fast do plates move relative to each other?

Centimeters per year

continental drift

Continental fracture is the idea that continents now separated by an ocean were once attached.

Which epoch saw the most fluctuations between normal and reverse polarity?

Matuyama

Great Rift Valley

The __________ is an example of a rift where land between two continents are being pulled apart.

subduction

The process in which tectonic plates sink back into the mantle called divergence

seafloor spreading

The process that creates new ocean crust by the upwelling of magma at ocean ridges

subduction

When a collision between an oceanic plate and a continental plate pushes the oceanic plate into and under the continental plate __________ takes place.

rift

When a divergent boundary occurs on land a __________, or separation, will arise and over time, that mass of land will break between them.

trench

When oceanic plates collide with continental plates a __________ will form between the two plates.

subduct

When oceanic plates collide, one of those plates will __________ (go beneath the other

denser

When plates collide the plate that is __________ will subduct (go beneath the other).

magnetometer

a device that measures magnetism

isochron

a line on the map that denotes crust that formed at the same time.

What was Wegener's hypothesis called?

continental drift

Which is a convergent boundary that does not have a subduction zone?

continental-continental

Pangea

plate tectonics is the name given to the single continent that existed 200 mya

which suggested to early cartographers that the continents were once joined?

shape of continents

The weight of a subduction plate helps pull it into a subduction zone in which process?

slab pull

What process creates deep-sea trenches?

subduction

subduction, convergent boundary

subduction takes place in this boundary more dense plate goes under a less dense plate

divergent boundary, transform boundary

both ways that the plates move around relative to each other when they break

As shown, which direction does the icy water move?

down

Which feature forms along this type of boundary? C-C

folded mountains

tectonic plate

huge pleas of crust and rigid upper mantle that fit together at their edges to cover earth surface

Which observation was not instrumental in formulating the hypothesis of seafloor spreading?

identifying the location of glacial deposits

Which is modeled by the water movement?

mantle convection

paleomagnetism

the study of the history of Earth's magnetic field

continental drift, plate tectonics

the way in which these plates move - the plates are moved to continental drift to explain the movement of the earth's surface

slab pull

the weight of a subduction zone pulls the trailing slab into the subduction zone

ridge push

the weight of the uplifted ridge is thought to push the oceanic plate toward the trench formed at the subduction zone

Which is not a force causing plates to move?

volcanism

seafloor spreading, magnetic reversal

you can see the polarity of the Earth's magnetic field in rocks - in the ocean's crust

Generally, what is the age of the oceanic crust?

younger than the continental crust