Theory of Plate Tectonics

1) What are the types of plate boundaries and where are they located?

2) What features are found at each plate boundary.

3) How do the plates move?

Day 1: What is Plate Tectonics

• The Earth’s crust and upper mantle are broken into several movable sections called plates

• Unifying Theory of Geology. • Explains why we have mountains,

volcanoes, earthquakes, the rock cycle etc.

Plate Boundaries

There are only 3 types of plate boundaries

Divergent and Convergent Boundaries

Divergent Boundaries• Boundary between two plates

that are moving apart.

• Divergent boundaries cause

SEAFLOOR SPREADING

Boundary Type 1

Features of Divergent Boundaries

• Mid-ocean ridges• Rift valleys• Magma fills gap and causes

underwater volcanoes

Atlantic Ocean is getting BIGGER

Convergent Boundaries

• Boundaries between two plates that are colliding

• There are 3 types…

Boundary Type 2

Convergent Type 1• Ocean plate colliding with a

less dense continental plate• Subduction Zone: where the

more dense plate slides under the less dense plate

• VOLCANOES occur at subduction zones

Andes Mountains, South America

Convergent Type 2

• Ocean plate colliding with another ocean plate

• The more dense plate slides under the less dense plate creating a subduction zone called a TRENCH

Convergent Type 3

• A continental plate colliding with another continental plate

• Have Collision Zones:–a place where folded and thrust

faulted mountains form.

Transform Fault Boundaries• Boundary between two plates that

are sliding past each other• EARTHQUAKES often occur

along faults• San Andreas Fault

Boundary Type 3

San Andreas Fault, CA

Day 2: Review Questions...• What are the three types of plate

boundaries?• Draw arrows to show what

direction do plates go for each? • List two or three major features or

events that occur at each boundary?

Day 3: Causes of Plate

Tectonics

Convection Currents• The Earth’s solid Lithosphere (the crust and

upper part of the mantle) floats like a raft on the partially melted athenosphere.

• Fluid rock in the athenosphere moves toward the surface, cools, then sinks again.

• Creates convection currents beneath the plates that cause the plates to move like a conveyor belt..

Convection currents in the athenosphere cause the plates to move. Notice that divergent boundaries occur where hot material is rising and convergent boundaries occur where hot material is sinking.

Day 3: cont..

Day 3: Questions...

• What causes plates to move?• How is a convection current

formed?

Day 4: Quiz (Rockin!!!)