1. Plate boundaries and Tectonic processes

2. Arrows show direction of plate motion
THE MAJOR PLATES
Arrows show direction of plate motion

3. DIVERGENT BOUNDARIES: PLATES MOVE APART: Seafloor spreading
Creates ridge-rift systems and new seafloor
MID ATLANTIC RIDGE and GREAT AFRICAN RIFT VALLEY are examples

4. CONVERGENT BOUNDARIES
PLATES MOVE TOGETHER & COLLIDE
WHAT HAPPENS DEPENDS ON DENSITY:
Equal density – two continental plates – FOLDING (mountains)
Different densities – denser plate sinks – SUBDUCTION:
OCEAN – OCEAN PLATES : ISLAND ARCS
OCEAN – CONT. PLATES: VOLCANIC ISLAND CHAINS

5. CONVERGENT BOUNDARY– 2 CONTINENTAL PLATES: FOLDING
Since plates are of equal density – neither sinks – both buckle upwards – process of FOLDING produces FOLDED MOUNTAINS (Appalachians, Himalayas)

6. CONVERGENT - SUBDUCTION
Denser plate edge (oceanic) sinks into asthenosphere, is melted, and creates VOLCANIC MOUNTAIN RANGES (Cascades, Andes, Sierra Madres)

7. Ocean – ocean plate subduction
Older and denser plate edge (left) is subducted under younger / less dense plate (right). This forms VOLCANIC ISLAND ARCS (Aleutians, Japan, Indonesia)

8. TRANSFORM BOUNDARIES: PROCESS OF TRANSLATION
“SIDE TO SIDE” MOTION – CREATES FAULTS - EARTHQUAKES

9. Arrows show direction of plate motion
THE MAJOR PLATES
Arrows show direction of plate motion

10. So, Divergence and Convergence occur in balance

11. MAJOR EARTHQUAKE AND VOLCANO ZONES EXPLAINED- They occur along PLATE BOUNDARIES!
DIVERGENT: MID-ATLANTIC RIDGE – SEAFLOOR SPREADING
CONVERGENT - THE RING OF FIRE - SUBDUCTION

12. Formation of the Hawaiian Islands
HOT SPOTS – “Volcanic exceptions” – occur in middle of plates CLICK HERE TO VIEW ANIMATION
Formation of the Hawaiian Islands