Plate Tectonics

seamount

a volcanic mountain rising from the ocean floor that doesn't reach the surface

Where do earthquakes occur?

along all types of plate boundaries

subduction

The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.

Seafloor Spreading

The process that creates new seafloor as plates move away from each other at the mid-ocean ridges

Asthenosphere

The soft layer of the mantle on which the lithosphere floats.

Oceanic Lithosphere

made out of basalt; denser that's why it sits lower in the asthenosphere

Continental Lithosphere

made out of granite; not as dense as basalt that's why it sits higher up in the asthenosphere

What is created at an oceanic-oceanic divergent boundary?

mid-ocean ridges

What is created at a continental-continental convergent boundary?

mountains

lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle.

What is created at a transform boundary?

earthquakes

Divergent Boundary

A plate boundary where two plates move away from each other.

transform boundary

A plate boundary where two plates move past each other in opposite directions; earthquakes are common here

Convergent Boundary

A plate boundary where two plates move toward each other.

mid-ocean ridge

An undersea mountain chain where the new ocean floor is produced; a divergent plate boundary.

convection currents

Circular currents in the mantle caused by the magma being heated by the core of the Earth.

tectonic plates

a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle

volcanic island

an island formed when an underwater volcano builds up enough lava and ash to rise above sea level

Trench

extremely deep areas in the ocean that are created by a subducting plate

What is created at an continental-continental divergent boundary?

rift valley

What is created at an oceanic-continental convergent boundary?

trenches, coastal mountains, volcanoes

What is created at an oceanic-oceanic convergent boundary?

trenches, island arcs, volcanoes