TerminologyTerminology The term “plate” refers to the subdivision of the earth’s The term “plate” refers to the subdivision of the earth’s

crust and lithosphere.crust and lithosphere.

The term “tectonics” refers to the deformation of the The term “tectonics” refers to the deformation of the earth’s crust.earth’s crust.

““Plate tectonics” refers to the formation and migration of Plate tectonics” refers to the formation and migration of these plates.these plates.

Subduction zone is where two plates come together, and Subduction zone is where two plates come together, and one is forced below the other.one is forced below the other.

It is puzzling!It is puzzling! Alfred Wegener developed a Alfred Wegener developed a

theory that states that all theory that states that all present continents were once present continents were once together and collectively together and collectively known as a 'supercontinent' known as a 'supercontinent' called a Pangaea.called a Pangaea.

The Pangaea theory was The Pangaea theory was treated with much skepticism treated with much skepticism when it was first raised. But when it was first raised. But since then, there have been since then, there have been much evidence to support this much evidence to support this theory. theory.

There are 3 types of boundaries:There are 3 types of boundaries: Divergent plate boundariesDivergent plate boundaries

Convergent plate boundariesConvergent plate boundaries

Transform plate boundariesTransform plate boundaries

Divergent plate boundariesDivergent plate boundaries Divergent plate boundaries are where two plates move apart or Divergent plate boundaries are where two plates move apart or

separateseparate

Magma is heated by convection, rises and pushes the plates apartMagma is heated by convection, rises and pushes the plates apart

This creates a new sea floorThis creates a new sea floor

Also called seafloor spreadingAlso called seafloor spreading

Rifts and RidgesRifts and Ridges Great Rift Valley in Great Rift Valley in

AfricaAfrica

Mid-Atlantic RidgeMid-Atlantic Ridge

Back to boundary types

Convergent BoundariesConvergent Boundaries This is where two plates come togetherThis is where two plates come together One plate is forced to sink below the otherOne plate is forced to sink below the other Subduction zone Subduction zone There are three types of convergent boundaries:There are three types of convergent boundaries:

• Ocean-continentOcean-continent• Ocean-oceanOcean-ocean• Continent-continentContinent-continent

Back to types of boundaries

Oceanic-continentalOceanic-continental The subduction zone is where the oceanic plate is forced below The subduction zone is where the oceanic plate is forced below

the continental plate.the continental plate.

A deep trench is formed off shoreA deep trench is formed off shore

A mountain range is formed on landA mountain range is formed on land

An example is the West coast of North AmericaAn example is the West coast of North America

Back to convergent boundaries

Oceanic-OceanicOceanic-Oceanic Where two oceanic plates Where two oceanic plates

convergeconverge

A deep ocean trench is A deep ocean trench is formedformed

A island chain of volcanoes is A island chain of volcanoes is formedformed

Examples would be Hawaii or Examples would be Hawaii or JapanJapan

Back to convergent boundaries

Continent-ContinentContinent-Continent Where two continental plates come togetherWhere two continental plates come together

The plates push together to form a chain of high, jagged The plates push together to form a chain of high, jagged mountainsmountains

Examples would be The HimalayasExamples would be The Himalayas

back

Transformation boundariesTransformation boundaries This occurs between two This occurs between two

plates that scrape against plates that scrape against each othereach other

At this type of boundary, a At this type of boundary, a fault is createdfault is created

A common result is an A common result is an earthquakeearthquake

A very well known example is A very well known example is the San Andreas Fault in the San Andreas Fault in CaliforniaCalifornia

Now, let’s review!Now, let’s review!

1) At a divergent plate boundary, 1) At a divergent plate boundary, how do plates move?how do plates move?

aa) Grind past each other) Grind past each other

bb) Collide with each other) Collide with each other

cc) Rift apart) Rift apart

d) Move under each otherd) Move under each other

2) Oceanic trenches are formed by:2) Oceanic trenches are formed by:

aa) Sea-floor spreading) Sea-floor spreading

bb) The collision of continents) The collision of continents

cc) The subduction of oceanic crusts into ) The subduction of oceanic crusts into the earth’s mantlethe earth’s mantle

dd) The subduction of continental crust ) The subduction of continental crust into the earth’s mantleinto the earth’s mantle

3) The supercontinent composed of 3) The supercontinent composed of all of the continents proposed by all of the continents proposed by Alfred Wegener is called:Alfred Wegener is called:

aa) Mantle) Mantle

bb) Pacific) Pacific

cc) Pangaea) Pangaea

dd) Plate tectonics) Plate tectonics

4) Where would an earthquake 4) Where would an earthquake happen?happen?

aa) At a divergent plate boundary) At a divergent plate boundary

bb) At a convergent plate boundary) At a convergent plate boundary

cc) At a transform plate boundary) At a transform plate boundary

5) 5) What is What is notnot a result of plate a result of plate tectonics?tectonics?

aa) Hurricanes) Hurricanes

bb) Volcanoes) Volcanoes

cc) Earthquakes) Earthquakes

dd) Mountains) Mountains