Plate tectonics 8.9B Lesson

Theory of Plate Tectonics

The lithosphere is broken into Tectonic Plates

• The lithosphere is made from the crust and the uppermost part of the mantle

• The lithosphere is rigid, brittle rock

• These plates float on the asthenosphere

How do the plates ACTUALLY MOVE?

• Convection currents in the asthenosphere drive the movement of lithospheric plates

The earth moves!

Our earth moves! We have many pieces of evidence for this some we can even feel; like earthquakes. So what is causes the movement? Magma! Deep in the Earth, molten rock churns as it heats and cools in convection currents. This moves the crustlike plates on top, and even creates and new and destroys old plates. *VIDEO TIME*

Multiple Choice

Convergent boundaries occur when:

• Two plates pull apart

• Two plates collide

• Two plates scrape/slide past each other

Multiple Choice

Divergent boundaries occur when:

• Two plates pull apart

• Two plates collide

• Two plates scrape/slide past each other

Multiple Choice

Transform boundaries occur when:

• Two plates pull apart

• Two plates collide

• Two plates scrape/slide past each other

Multiple Choice

Subduction zones occur when:

• Two plates collide at and convergent boundary and one sinks

• Two plates collide at a convergent boundary and they push each other up

• Two plates pull apart at a divergent boundary

Multiple Choice

Seafloor spreading occur when:

• Two plates collide at and convergent boundary and one sinks

• Two plates collide at a convergent boundary and they push each other up

• Two plates pull apart at a divergent boundary

Multiple Choice

Mountain building occurs when:

• Two plates collide at and convergent boundary and one sinks

• Two plates collide at a convergent boundary and they push each other up

• Two plates pull apart at a divergent boundary

Convergent Boundaries

• Collide (crash into eachother)

• Create mountains, trenches, volcanoes

• Destroys crust during subduction

Subduction

At a convergent boundary, plates collide. Heavier (more dense) oceanic crust goes under and melts into the mantle. This destroys the crust.

Divergent Boundaries

• Plates move apart

• Creates mid - ocean ridges and rift valleys

• Creates new crust through Seafloor Spreading

Labelling

Match them to the correct plate tectonic boundaryu

Drag labels to their correct position on the image

Transform

Convergent

Divergent

Hotspot

Where would you most likely find a mountain?

Seafloor Spreading

At a divergent boundary, two oceanic plates move apart. This allows mantle material to rise and cool, forming new crust. Older crust moves further away.

Labelling

Where is the young crust found? where would the old crust be found?

Drag labels to their correct position on the image

Older Crust

Young Crust

Transform Boundaries

• Plates slide past each other

• Creates faults

• Does not destroy or create crust