CATALYST

• Describe the 3 types of plate boundaries.• Explain how

convection currents move plates.

1. Describe 1 type of plate movement.

OBJECTIVES

DATE: 02/10/2015

Plate Tectonics

• Earth’s crust is divided into 12 major plates (tectonic plates) which are moving in various directions.• Plate Boundary–Where 2 plates meet

Plate Tectonics

Types of Plates

Continental Crust• Thick (10 - 70 km)• Less Dense• Mostly very old

Oceanic Crust• Thin (~7 km)• More Dense• Young age of rocks

Plate Boundaries

1. Divergent Boundaries2. Convergent Boundaries

a. Oceanic-Oceanicb. Oceanic-Continentalc. Continental-Continental

3. Transform Boundaries

1. Divergent Boundaries

• 2 or more plates separate or pull apart• Magma rises between the plates and

makes new rocks• Formation of ridges (in the ocean) and

rift valleys (on the continents)

1. Divergent Boundaries

1. Divergent Boundaries

1. Divergent Boundaries

2. Convergent Boundaries

• 2 or more plates moving towards each other• 3 types

a. Oceanic-Oceanicb. Oceanic-Continentalc. Continental-Continental

2a. Oceanic-Oceanic

• Collision of 2 oceanic crusts• One oceanic crust will

eventually slide under the other

What will happen to the oceanic plate when it sinks?

2a. Oceanic-Oceanic

• Subduction–When a more dense plate

goes under (subducts) a less dense plate

2a. Oceanic-Oceanic

2a. Oceanic-Oceanic

• Trenches and Island Volcanoes form at this boundaries

2b. Oceanic-Continental

• Collision between an oceanic plate and a continental plate• Oceanic crust is more dense

than continental crust so…–Oceanic crust sinks below

continental crust

2b. Oceanic-Continental

Continental

Oceanic

What will happen to the oceanic plate when it sinks?

SUBDUCTION

2b. Oceanic-Continental

• Trenches and Land Volcanoes form at these boundaries

Plate Tectonics

2c. Continental-Continental

• Collision of 2 continental plates• Similar density, so neither subducts• Formation of mountains

2c. Continental-Continental

• Example: Indian-Australian Plate vs. Eurasian Plate–Collision formed

Himalaya Mountains

2c. Continental-Continental

3. Transform Boundaries

• 2 plates slide horizontally past each other• Forms long lines in the Earth

(faults) and deformation of the land

3. Transform Boundaries

3. Transform Boundaries

• Example: San Andreas Fault, CA

3. Transform Boundaries

But what is causing these plates to move?

Convection Currents!