EXPLORE: Plate Boundaries

1. Divergent, Convergent and Transform Boundaries

There are 3 major types of plate boundaries: divergent, convergent, and transform. The following screencast explains what happens at each of these plate boundaries, as well as the landforms and features associated with each. 

Sources: http://wikimediafoundation.org/wiki/File:Plates_tect2_en.svg

2. Ring of Fire

You will notice from this map that there are a lot of volcanoes located around the Pacific Ocean. This area is known as The Ring of Fire. Volcanoes occur in this area due to the subduction zones located around the edges of the Pacific Plate. Subduction zones occur at convergent plate boundaries, when an oceanic plate collides with either a continental plate or another oceanic plate. Because the ocean plates are made of very dense rock, one plate slips beneath the other.

In the Ring of Fire, ocean plates are being subducted when they collide with continental plates. For example, when the Pacific Plate and the Australian Plate collide, the denser Pacific Plate is pulled down beneath the less dense Australian Plate, causing volcanoes to form. On the west coast of South America, volcanoes form as the Nazca Plate (oceanic) is subducted beneath the South American Plate (continental). On the west coast of North America, volcanoes form as the Pacific and Juan de Fuca Plates are subducted under the North American Plate.

In the Ring of Fire, ocean plates are also being subducted beneath other oceanic plates. For example, the Aleutian Trench forms as the Pacific Plate is subducted beneath the North American Plate.