Plate Tectonics Movement of the Crust

Convergent Boundaries Plates Move Toward Each Other Three Types of Convergent Boundaries Oceanic-to-Continental Oceanic-to-Oceanic Continental-to- Continental

Oceanic-to-Continental Convergent Boundaries More dense oceanic crust subducts under the less dense continental crust. Characteristics include: - Trenches at subduction zone - Volcanoes - Deep Earthquakes

Andes Mountains in South America

Oceanic-to-Oceanic Convergent Boundaries An older, cooler, and more dense oceanic plate subducts under another oceanic plate Characteristics include: - Volcanic Activity - Earthquakes - Trenches

Continental-to-Continental Convergent Boundary Two continental crust plates collide. Since continental material is equally dense, movement is mostly upward. Characteristics include: - Tall mountains - Earthquakes

Continental-to-Continental Convergent Boundary

Collision of India and Asia

Himalaya Mountains

Other Characteristics of the Plate Tectonics Theory Volcanoes and Earthquakes are concentrated along Plate boundaries An example is the “Ring of fire” around the Pacific Ocean

Earthquakes are Also Concentrated Along Plate Boundaries

Hot Spots! An EXCEPTION to volcanoes and earthquakes occurring along plate boundaries are hot spots These occur where magma rises to the surface away from a plate boundary. An example is the Hawaiian Islands.

Plate Moves over Hot Spot, Creating an Island Chain

Map of Island Chain Created by the Hawaiian Hot Spot

What Causes the Plates to Move? The cause of tectonic (lithospheric) plate movement is convection currents in the plastic-like mantle, or the Asthenosphere

Plate Boundary Summary