Plate Boundaries

What are tectonic plates?

Tectonic plates are large, rigid slabs of Earth's lithosphere (crust and uppermost mantle) that move slowly over the asthenosphere.

What are plate boundaries?

Plate boundaries are the edges where two or more tectonic plates meet, and where most of Earth's seismic and volcanic activity occurs.

Describe a divergent plate boundary.

A divergent plate boundary occurs where two tectonic plates move away from each other, leading to the creation of new crust.

Describe a convergent plate boundary.

A convergent plate boundary occurs where two tectonic plates move towards each other, resulting in one plate sliding beneath the other (subduction) or the collision of both plates.

Describe a transform plate boundary.

A transform plate boundary occurs where two tectonic plates slide horizontally past each other, neither creating nor destroying crust.

What geological features are associated with divergent plate boundaries?

Divergent plate boundaries are associated with mid-ocean ridges, rift valleys, and volcanic activity as magma rises to fill the gap.

What happens at an oceanic-continental convergent boundary?

At an oceanic-continental convergent boundary, the denser oceanic plate subducts beneath the continental plate, forming an ocean trench, a volcanic arc on the continent, and earthquakes.

What happens at an oceanic-oceanic convergent boundary?

At an oceanic-oceanic convergent boundary, one oceanic plate subducts beneath the other, forming an ocean trench and a chain of volcanic islands known as an island arc.

What happens at a continental-continental convergent boundary?

When two continental plates collide, neither subducts significantly due to similar densities, leading to intense folding and faulting that forms large mountain ranges (e.g., the Himalayas).

What geological events are common at transform plate boundaries?

Transform plate boundaries are characterized by frequent earthquakes as the plates grind past each other, often along fault lines (e.g., the San Andreas Fault).