Theory of Plate Tectonics

1. Theory of Plate Tectonics Section 12-3 continued

2. Convection Currents • Movement of material caused by differences in temperature • Cooler denser mantle, farther from the core, sinks causing hotter material to push up and replace it • Reason for movement of plates • Convection Currents

3. Collision of Oceanic Crust with Continental Crust • Less dense continental plate rides over edge of oceanic plate pushing up and folding continental crust forming mountains ranges • Example: Andes Mountains, South America

7. Andes Oceanic Crust Collides with Continental Crust

8. The Andes – The Result of Subduction of Oceanic Crust beneath South American Plate

9. The Andes – The Result of Subduction of Oceanic Crust beneath South American Plate

10. The Andes – The Result of Subduction of Oceanic Crust beneath South American Plate

11. Collision of 2 Oceanic Plates • Older more dense plate is subducted under younger, being pushed down into the mantle, melting and rising as volcanoes causing island arcs • Example: Japan, Indonesia, Aleutians

12. Indonesia is a meeting place of two tectonic plates, Australia and Asia. The Australian plate was moved northward and subducted under the Eurasian plate. The subduction zone can be traced from northern tip of Sumatra until the Lesser Islands. This subduction also trigger the formation of volcanic range from Sumatra, Java to Lesser Islands.

14. Indonesia is a meeting place of two tectonic plates, Australia and Asia. The Australian plate was moved northward and subducted under the Eurasian plate. The subduction zone can be traced from northern tip of Sumatra until the Lesser Islands. This subduction also trigger the formation of volcanic range from Sumatra, Java to Lesser Islands.

19. Collision of 2 Continental Plates • Edges of continents buckle and fold to form large mountain ranges • Example: Appalachian Mountains • If both have the same density, edge of continent thickens and pushes upward • Example: Himalayan Mountains