Do we track plate movement?

• Scientists now

use satellites

to track the

movements of

the Earth’s

plates.

Interesting Fact!• Because of sea-floor spreading, the

distance between Europe and North

America is increasing by a few

centimeters per year.

Theory of Plate Tectonics• States that pieces of

Earth’s lithosphere are in a slow, constant motion, driven by convection currents in the mantle.

• As the plates move, they collide, pull apart, or grind past each other, producing spectacular changes in Earth’s surface. These changes include volcanoes, mountain ranges, and deep ocean trenches.

http://w3.salemstate.edu/~lhanson/gls110/GLS110_BasicConcepts.htm

Convection Currents and Sea-Floor Spreadinghttp://www.absorblearning.com/media/attachment.action?quick=12p&att=2775

Warm-up• Please read

textbook pages 150

– 154 with your

team. When you are

finished, you may

return to your desk

and begin the LAB

• Please be prepared

to share your

answers with your

neighbor.

CAPS

NameClarkScience PeriodDate

Share with your neighbor…

Warm-up

CAPS

• Please read

textbook pages 150

– 154 with your

team. When you are

finished, you may

return to your desk

and begin the LAB

NameClarkScience PeriodDate

There are three kinds of plate boundaries:

• Divergent boundaries, convergent

boundaries, and transform boundaries.

• A different type of plate movement

occurs along each type of boundary.

What are divergent boundaries?

• Divergent Boundary: where two

plates move apart

What happens at divergent boundaries?

• #1 - When two

oceanic plates move

apart, a mid-ocean

ridge is formed. EX:

Atlantic Mid-Ocean

Ridge

• #2 - When two

continental plates

move apart, a rift

valley is formed.

EX: Great Rift Valley

in Africa

We can see this above water in Iceland!

Hydrotherma, vents along mid-ocean ridges!

Black Smoker

Can things live in this superheated environment?

Tubeworms, palmworms,

scale worms and limpets

thrive in warm, diffusely

flowing vent fluids issuing

from the black smoker

chimney "Finn" on the Juan

de Fuca Ridge

Complex

communities

fueled by the

chemicals

dissolved in

the vent

fluids

What is a convergent boundary?

• Convergent

boundary: place

where two plates

come together.

• The result is a

collision where the

density of the crust

determines what

happens.

http://www.divediscover.whoi.edu/images/tectonics-collide.jpg

Convergent Boundary #1• Oceanic plate (more

dense basalt) meets

a continental plate

(less dense granite):

oceanic crust goes

under.

• Volcanoes are

created. Ex: Mt. St.

Helen’s/ Cascade

mountains

Convergent Boundary #2• When continental

plates meet (equal

density): mountains

are created.

• EX: Himalayas

Convergent Boundary #3• When two oceanic plates meet

(more density goes down)

• Trenches are created.

• EX: Mariana Trench between

Japan and New Guinea.

• Deepest part of the ocean but

not closest to the Earth’s core.

What is a transform boundary?• A boundary where two plates grind past each

other without the (no) production or destruction of lithosphere.

• However, earthquakes can occur along the faults. EX: San Andreas Fault

The San Andreas Fault

What does it do to Arizona?

When it comes to the Earth,it’s like a rug…

http://rst.gsfc.nasa.gov/Sect2/Sect2_6.html

• Over millions of years, the forces of plate

movement can change a flat plain into

landforms such as anticlines and synclines,

folded mountains, fault-block mountains, and

plateaus.

Folding Earth’s Crust• This results in

mountains and

plateaus.

• EX: Colorado

Plateau

Rockies were never volcanoes.