Plate Tectonics and Geologic Time

Plate Tectonics

An Introduction

​Practice with purpose games and word wall

There was once a time when you could take a stroll from North or South America to Africa no problem!

Plate tectonics theorizes that Earth's outer layer is made up of large, moving pieces called plates! These plates are in constant motion.

Assignment: EdPuzzle

Title:
What are Tectonic Plates? Our Earth and Its Movements
After video: class discussion:
What are the basic layers of the Earth?
What are the possible outcomes of plate movement?
How do fossils support the idea of Pangea, the super continent?
If the inner core is so hot why is it solid?

Multiple Choice

About how fast do you think the tectonic plates move?

• As fast as students leave school at the end of the day

• As fast as your nails grow

• As fast as you can run

Tectonic plates move about as fast as your fingernails grow -

That's 1-6 inches a year!

3 Theories of plate tectonics
Convection
Slab pull
Ridge Push.

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What causes tectonic plates to move?

​Convection

the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.

These plates move due to heat from Earth's core.

• Heat rises at spreading centers, pushing plates apart

• This process resulted in the breakup of Pangea, the formation of the Atlantic Ocean, and how Earth's surface appears today!

slab pull

This force is  caused by the sinking of cold, dense mantle material at subduction  zones. As the old mantle material sinks back into the Earth, it pulls  the tectonic plates along with it.

​subduction zones are where the slabs are pulled underneath (because they cool and are more dense)

the upward movement of hot mantle material at mid-ocean  ridges. As the new mantle material rises to the surface, it pushes the  older, cooler mantle material away. This creates a ridge push force that  moves the tectonic plates apart.

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Ridge push

Multiple Choice

What do you think happens when two plates converge (collide)?

• Mountains form

• A trench forms

• They change course and move somewhere else

Through collisions, plates can raise incredible mountain ranges!

The Himalayan mountains formed as the Indian plate crashed into the Eurasian plate.

Multiple Choice

What's the smartest mountain in the world?

• Mount Cleverest

Multiple Choice

Which mountain range (hint: it is close to home!) also formed due to the collision of plates?

• The Andes

• The Appalachians

• The Cascades

• The Transantarctic Mountains

Types of Plate Boundaries

Describe the different types of plate boundaries

Divergent Boundary

- Place where 2 plates move apart

-Most occur in the ocean and form mid-ocean ridges

-When they occur on land, rift valleys form

Divergent Oceanic

-Example-Mid Atlantic Ridge

Multiple Choice

When a divergent boundary occurs on land, which landform does it create?

• mid-ocean ridge

• rift valley

• new ocean floor

• subduction zone

Multiple Choice

Which type of boundary involves the plates moving horizontally, side by side?

• convergent

• divergent

• transform

Transform Boundary

-Place where two plates slip past each other side by side

- Crust is neither created nor destroyed

-Earthquakes frequently occur along these boundaries

Multiple Choice

What are transform boundaries known for?

• earthquakes

• volcanoes

• mid-ocean ridges

• rift vallies

Multiple Choice

What geologic feature/event you be most likely to find at a transform boundary?

• Earthquakes
• Volcanoes
• Mountains
• Rift Valleys

Multiple Choice

The process when one crust goes under another is called

• sea floor spreading

• convergency

• subduction

• rifting

Multiple Choice

What kind of plate boundary is shown here?

• divergent
• convergent
• transform
• subducting

Multiple Choice

This type of Boundary results when plates separate

• Divergent

• Convergent

• Transform

Multiple Choice

Type of Boundary where plates collide

• Divergent

• Convergent

• Transform

That's right! Next time you hike in Shenandoah National Park, know that you are among mountains that started forming over 400 million years ago (that's before life even left the ocean!).

Thank you!