geology exam 1 flashcards

Divergent boundary

plates move apart ← →

Convergent plate boundary

Plates move toward each other → ←

Transform plate boundary

Plates slide past each other horizontally ←

→

Where do you find divergent boundaries?

Mostly along mid-ocean ridges and some rift valleys

Where do you find convergent boundaries?

Often where oceanic and continental plates meet or where two continental plates collide

Where do you find transform boundaries

Common along faults, especially on continents

What do divergent plate boundaries do?

Create new crust

What do convergent plate boundaries do?

cause mountains, volcanoes, and earthquakes

What do transform boundaries do?

Cause earthquakes

 In general, is oceanic crust older or younger than continental crust?

younger

In general, is oceanic crust denser or less dense than continental crust?

denser

What is the primary mechanism driving plate tectonics?

convection in Earth’s mantle, caused by heat from inside the Earth.

 Can you name a secondary mechanism which is associated with subduction?

Slab pull

What is a slab pull

As a dense oceanic plate sinks into the mantle at a subduction zone, it pulls the rest of the plate along with it. This is considered an important force driving plate movement.

 Where is the mid-oceanic ridge?

found in the middle of ocean basins, where tectonic plates are moving apart

Why is the mid atlantic ocean ridge important

it is where new oceanic crust is created and it is the longest and largest mountain range

What is seafloor spreading?

As the plates separate, magma rises from the mantle, cools, and forms a new crust.

 How are magnetic reversals important to understanding plate tectonics?

they provide evidence for seafloor spreading and plate tectonics. As magma cools at the mid-ocean ridge, iron minerals in the new rock line up with Earth’s magnetic field. Because Earth’s magnetic field has reversed direction many times, the ocean floor contains alternating stripes of normal and reversed magnetic polarity. The matching stripes on both sides of the ridge show that new crust is forming and spreading outward.

Where is divergence at

The ridges

Where is convergence at ?

The trenches

What drives divergence and convergence

Convection in the mantle