Four types of plate boundaries Flashcards
Explain the four type of plate boundaries.
Constructive- Plates are dragged apart so they move away from one another and new crust is created.
Destructive- Where oceanic plates crash into other plates and are subducted into the mantle and destroyed.
Collision- Two continental sections of crust crash into each other and are pushed into large mountain ranges.
Conservative- Where plates slide past each other. Crust is not created or destroyed.
Why do plates move?
In the mantle convection currents are generated. These move heated rock upwards from the core, towards the crust. The currents spread out at the surface underneath the crust. Here it cools and sinks back down again, dragging the plate along.
What is formed by constructive plate margins.
Mid-ocean ridges. The plates move away from each other, usually underneath the ocean. Magma wells up in the mantle to plug the gap and the rising of material pushes up the crust slightly at either side, creating a mid ocean ridge.
Gentle volcanic activity along these margins.
What is formed by destructive plate margins?
A denser and heavier oceanic plate moves towards a lighter and thicker continental plate. The oceanic plate is subducted underneath the continental plate, creating a landform called a deep ocean trench. e.g. Peru-Chile Trench.
The oceanic plate is melted due to the friction. The magma rises, forcing its way through the crust. Pressure builds and the magma forces its way to the surface violently.
What is formed by collision plate margins?
Fold mountains are formed when two plates of similar densities converge (continental plates). Type of destructive plate boundary.
