1. Plate boundary interactions
separating
coming together
sliding past one another
Plate boundary interactions

2. ridge rift ridge
Plates are pushed aside as convection currents diverge; magma rises to crust
Creates ridges
rift valley
ridge ridge
and rift valleys
animation
DIvergent boundaries

3. Basaltic magma surfaces at these boundaries;
volcanism
Iceland
Ethiopia
East African rift valley

4. Sea Floor Spreading also contains a record of the shifts of the Earths magnetic field.

5. Convergent boundaries
Creates mountains as plates fold and crumple;
No volcanism
Continent–to-Continent
metamorphic
granitic rocks
Convergent boundaries

6. Alps
Folding

7. Himalayas
Alps

8. Convergent boundaries
Oceanic plates dive beneath continental in subduction
Continent–to-Oceanic
heat and pressure as the plate subducts, + water lowers the melting temp of the mantle, produces magma;
volcanism
trench
subduction
At the point where two plates collide, one plate may be pushed under the other plate, so that it sinks into the mantle. This process, called subduction, typically forms a trench, a very deep ditch, usually in the ocean floor. As the rigid lithosphere pushes down into the hot, high-pressure mantle, it heats up. Many scientists believe that the sinking lithosphere layer can't melt at this depth, but that the heat and pressure forces the water (the surface water and water from hydrated minerals) out of the plate and into the mantle layer above. The increased water content lowers the melting point of the mantle rock in this wedge, causing it to melt into magma. This sort of magma production is called subduction zone volcanism.
Magma a mix of oceanic/continental plates rock – andesite
Convergent boundaries

9. Trenches Peru-Chile trench Aleutian trench Pacific ocean South America
Alaska
Pacific ocean
Peru-Chile trench
Aleutian trench

10. Mt Lassen
The Cascades