Plate Tectonics The theory that explains how large pieces of the Earth’s outermost layer, called tectonic plates, move and change shape. http://www.youtube.com/watch?v=JmC-vjQGSNM

Plate Tectonic Boundaries Plate Boundary: Place where two tectonic plates meet (Like the seams on a puzzle that is put together) All tectonic plates share boundaries with other tectonic plates. There are 3 types of plate boundaries. The type of boundary depends on how the two plates interact.

3 Types of Boundaries Convergent Divergent Transform

Convergent boundary: the boundary formed by the collision of two lithospheric plates

1. Continental - Continental When continental plates collide, they buckle and thicken, which pushes the continental crust upward. (Remember c, c)

Continental - Continental Before collision After collision

Results: Mountain building

2. Continental- Oceanic Collision When a plate with oceanic crust collides with a plate with continental crust, the denser oceanic crust sinks (subducts) into the asthenosphere.

Result: Trenches, Volcanoes

3. Oceanic- Oceanic Collisions When two tectonic plates with oceanic lithosphere collide, one of the plates with oceanic lithosphere is subducted, or sinks, under the other plate.

Result: Trenches, Under water volcanoes or island formation

Divergent Boundary The boundary between two tectonic plates that are moving away from each other

Oceanic Separation RESULT: Oceanic Separation = mid-ocean ridge (new seafloor) Two oceanic plates separate from each other. As they move apart, magma rises to fill the gap.

Result: Continental Separation Continental Separation = rift valley Two continental plates separate from each other. As they move apart, magma rises to fill the gap.

Transform Boundary When plates are sliding past each other horizontally (Remember translations in math class = sliding shapes)

Continental or Oceanic Plates Slide As two plates slide past each other, their irregular edges grind and jerk.

Result: Earthquakes

Remember: Lithospheric plates are moved by convection currents within the asthenosphere. Lithospheric plates move apart when magma rises.

1. Volcanic islands 2. Subduction zone 3. Mid-ocean ridge 4. Magma 5. Oceanic crust 6. Trench