Plate Tectonics • Topics

1. Lithosphere Definition

a) Types of lithosphere

2. Movement of lithospheric plates

a) Convection Currents

b) Plate Tectonics Theory

3. Plate Boundaries

a) Transform

b) Convergent

i. Continental-Oceanic

ii. Contiental-Continental

iii. Oceanic- Oceanic

c) Divergent Boundaries

4. Features at Plate Boundaries

Lithosphere The outer shell of Earth that is made of rigid crust

and upper mantle

Lithosphere Together the lithospheric crust and upper mantle are broken into moving masses

called tectonic plates

2 Types of Lithosphere Oceanic Crust

Made up of the ocean floor. (Heavier and older than continental)

Continental Crust

Made up of continental landmasses.

Oceanic Crust vs. Continental Crust

How do the lithospheric

plates move?!

2) Convection currents

• Unequal heating from the Earth’s core causes hotter magma to rise and cooler magma to sink down towards the core and heat up

http://youtu.be/ryrXAGY1dmE

https://www.youtube.com/watch?v=ryrXAGY1dmE

Theory of Plate Tectonics (1960)

Earth’s lithosphere

consists of rigid, but moving masses called

tectonic plates

Tectonic Plates

There are 8 major plates and several minor plates

Plate Boundaries

There are 3 main ways that the plates

interact.

Points of interaction are called boundaries

3 Types of Plate

Boundaries…

1. Divergent Boundaries Where two plates are

moving apart,

magma rises and fills space between plates creating new

crust as it cools

CRUST IS GAINED

Divergent boundaries

2.Transform Boundaries

• Plates horizontally slide past one another

3. Convergent Boundaries

When two plates collide

(CRUST IS LOST)

• There are 3 types of

convergent boundaries

1. Continental + Oceanic Convergence

• When an oceanic plate collides with a continental plate. The oceanic plate will subduct under the continental plate.

2. Cont. + Cont. Convergence

• Two continental plates collide, crumple, and uplift

3. Oceanic - Oceanic Convergence

• The older and denser oceanic plate subducts under the lighter oceanic plate forming a trench

Features at Plate Boundaries

Divergent Boundary Features

1. Divergent boundaries

• 1. Mid-ocean ridges: Underwater mountain range

that winds throughout the

Earth’s oceans. It is the 40,000

miles long

New Crust Forms Here As Crust is Pulled Apart

2. Rift Valley: When the crust is pulled or ‘rifted’ apart, valleys form with steep walls

Transform Boundary Features

Transform Boundaries

Earthquakes occur when

stress is too great from plates sliding, causing fracture to form in the crust

Example: San

Andreas Fault

Convergent Boundary Features

Oceanic- Continental Convergent Boundary

Features

(Example: Andes Mountains)

1. Continental Volcanic Arc

2. Trench (subduction zone)

Trench= Deep depression in the ocean floor (caused

by subduction)

3. SUBDUCTION ZONE

Subduction zones occur when a plate sinks beneath another plate

Oceanic- Oceanic Convergent Boundary

Features

1. Volcanic Island Arc Magma rises to the surface along the trench and slowly forms an volcanic island. As the plate moves, a chain of volcanoes will form a volcanic island arc

2. Trench (Subduction zone)

Continental- Continental Convergent

Boundary Features

(Example: Appalachian Mountains and Mt.

Everest)

1. (Folded) Mountains

Appalachian Mountains

Folded Mountains

Appalachian Mountains

As compressional force increases, folded mountains form

Himalayan Mountains

http://www.pbs.org/wgbh/aso/tryit/tectonics/#

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