more plate tectonics

Plate boundaries

The edges where two tectonic plates meet and interact.

Types of plate boundaries

Convergent, Divergent, and Transform boundaries.

Convergent plate boundary

Plates move toward each other (collide).

Types of convergent boundaries

Ocean-Ocean, Ocean-Continent, Continent-Continent.

Subduction

The process where one tectonic plate sinks beneath another into the mantle.

Oceanic plate subducts beneath another oceanic plate

Forms volcanic island arcs and oceanic trenches.

Oceanic plate subducts beneath a continental plate

Forms continental volcanic arcs, trenches, and mountains.

Continental plates collide

Forms large mountain belts like the Himalayas.

Example of an Ocean-Ocean convergent boundary

The Aleutian Islands.

Example of an Ocean-Continent convergent boundary

The Andes Mountains.

Example of a Continent-Continent convergent boundary

The Himalaya Mountains.

Common features of convergent boundaries

Subduction, volcanoes, trenches, deep and shallow earthquakes, and mountain belts.

Divergent plate boundary

Plates move apart from each other.

Geological feature after a divergent boundary

Rift valleys.

Magma at divergent boundaries

It rises to fill the gap, forming new crust.

Divergent boundaries and subduction

No.

Divergent boundaries and volcanoes

Sometimes, but not typically large volcanic systems like arcs.

Example of a divergent boundary

The East African Rift Valley.

Transform plate boundary

Plates slide past each other horizontally.

Transform boundaries and subduction

No.

Transform boundaries and volcanoes

No.

Major hazard at transform boundaries

Large earthquakes.

Example of a transform boundary

The San Andreas Fault.

Volcanic arc

A curved chain of volcanoes formed above a subduction zone.

Difference between volcanic island arc and continental volcanic arc

Island arcs form on oceanic crust; continental arcs form on continental crust.

Example of a volcanic island arc

The Aleutian Islands.

Example of a continental volcanic arc

The Andes Mountains.

Oceanic trench

A deep, narrow depression in the ocean floor formed at subduction zones.

Location of oceanic trenches

At Ocean-Ocean and Ocean-Continent convergent boundaries.

Formation of mountain belts

The collision of two continental plates.

Plate boundary associated with large earthquakes

Transform boundaries.

Earthquakes at plate boundaries

Yes, but the type and depth vary.

Plate boundary that created the Himalaya Mountains

Continent-Continent convergent boundary.

Plate boundary that created the Andes Mountains

Ocean-Continent convergent boundary.

Plate boundary that created the East African Rift Valley

Divergent boundary.

Plate boundary represented by the San Andreas Fault

Transform boundary.

Why volcanoes form at subduction zones

The subducting plate melts and produces magma, which rises to form volcanoes.

Why transform boundaries don't produce volcanoes

There's no subduction or melting of plates to generate magma.

Formation of new crust

At divergent boundaries, magma rises and solidifies between separating plates.

Difference in crust creation and destruction

Divergent = new crust is created; Convergent = crust is destroyed (subduction).