Plate boundaries

8-3.6Chapter 6, lesson 3

Page 198-205

Divergent boundary

• Where 2 plates are moving apart• Most are located along mid-ocean ridge (sea

floor spreading)• New crust forms b/c magma pushes up &

hardens between separating plates

Convergent boundary

• Where 2 plates come together & collide• Activity depends on the types of crust that meet• More dense oceanic plate slides under less dense

continental plate or another oceanic plate -subduction zone , some crust is destroyed

• 2 continental plates converge, both plates buckle & push up into mountain ranges

Transform boundary

• Where 2 plates slide past each other• Crust is neither created nor destroyed• Earthquakes occur frequently along this type

of boundary

Changes of Landforms over Geologic Time

• Plates move @ very slow rates- from about 1 to 10 cm per year

• At 1 time- continents joined together in one large landmass called Pangaea

• As plates continued to move & split apart, oceans were formed, landmasses collided 7 split apart until Earth’s landmasses came to be in the positions they are in now

Evidence

• Evidence of these landmasses, collisions, & splits comes from fossils, landform shape, features, rock structures, & climate changes

• Landmasses changes can occur at hot spots within the lithospheric plates

• Hot spot- area of volcanic activity in the middle of a tectonic plate

• Earth’s landmasses will continue to move & change during the geologic time of the future