Plate Boundaries and Interactions

Plate Boundaries

The regions where the tectonic plates meet are aptly called…

➔ The regions between two plates.

➔ Depending on their motions with respect to one another, these plate boundaries are any of three kinds: divergent, convergent and transformative. Furthermore, as the plate move, fractures on the Earth’s crust develop.

Divergent Plate Boundary

When two tectonic plates at a location move away from each other.

Rift Valley

When two plates move away from each other, a gap or rift between them is created. As the plates move away, the space between them is filled with magma that forms underneath. Molten lava rises, cools, and becomes part of the ocean floor. If the gap eventually widens, it then evolves into what?

Mid-oceanic Ridge

Divergent boundaries between oceanic plates produce ___________ _____, a mountain system that is formed on the seafloor.

Convergent Plate Boundary

Occur when two plates slide toward each other and form either a subduction zone (one plate moves underneath the other) or an orogenic belt.

Orogenic Belt

Is a region of deformed rocks that is formed when two plates collide and one plate crumples and is uplifted.

Oceanic-Oceanic, Oceanic-Continental, and Continental-Continental

Three kinds of convergence.

Oceanic Trench

A long, narrow depression in the ocean floor called _______ ______ is also created at the subduction zone.

When two oceanic plates collide a subduction zone is formed. The descending oceanic plate begins to melt upon contact with the asthenosphere. The molten material begins to rise, creating a chain of volcanoes. Through time, volcanic debris from the eruption of underwater or submarine volcanoes pile up until an island volcano rises above sea level.

What happens in an Oceanic-Oceanic collision?

The denser oceanic plate moves underneath the lighter continental plate. As the oceanic plate descends into the mantle, the temperature increases, causing the rocks to melt and form magma. This hot and less dense magma will eventually seek a vent, which in most cases are existing volcanoes, to reach the surface.

What happens in an Oceanic-Continental subduction?

No subduction happens. Instead, the continents suture themselves. The continental crust buckles and rocks pile up, creating mountain ranges.

What happens when two continental plates collide?

Transform Plate Boundary

The plates slide against each other in opposite directions. No mountains or volcanoes are produced. Instead, a massive amount of energy is released, causing earthquakes.