There are 3 main types of plate boundaries: 1. Divergent 2. Convergent 3. Transform

Divergent Boundaries Also known as spreading centers. 2 lithospheric plates are moving APART (diverging). Most are found on the seafloor, forming ocean ridges.

Bridge over divergent boundary in Iceland

Because of this, some of the world’s oceans are getting bigger! Ocean ridges have valleys called rift valleys. The rift valleys are broken into fracture zones. These are the sources of earthquakes and Volcanoes.

Rift Valley in Iceland

Convergent Boundaries This is when 2 tectonic plates are being pushed TOGETHER.

Three types of convergent boundaries: 1.Ocean-Ocean crust convergence 2.Ocean-Continental crust convergence 3.Continental-Continental crust convergence

Ocean-Ocean Convergence and Ocean- Continental Convergence: 2 oceanic plates coming together or 1 ocean plate and one continental plate coming together. One plate will be pushed under the other (the Most dense plate goes under the least dense plate).

This is called subduction. Subduction creates trenches. The subducted plate melts and this will form volcanoes or island arcs (volcanic islands).

Ocean-Continental Convergence Animation Ocean-Ocean Convergence Animation

The Andes

Continental-Continental Convergence: 2 continental plates are coming together. When they collide, NO subduction occurs because continental crust is not very dense and one will not subduct another. Instead, the crust gets crumpled and uplifted and often creates mountain ranges. The most famous is the Himalayas when India collided with Eurasia.

India colliding with Eurasia animation

Old ocean sediments Uplifted plateau mountains

Transform Boundaries: 2 plates SLIDE past each other. Crust will be deformed and fractured due to the friction and stress. This will create faults and cause earthquakes at these boundaries. Most famous transform fault is the San Andreas Fault in California.

San Andreas Fault Picture

Stop Plate Tectonics It’s Changing The Earth