Heat in the EarthThe heat in the Earth is produced from the

breakdown (decay) of radioactive isotopes.

When these isotopes decay they release a lot of chemical and nuclear energy which generates tons of heat energy.

Plate BoundariesWhat is a plate boundary?A: Where two plates touch each other. (Like two

puzzle pieces)

There are three types of plate boundaries.

The type of boundary depends on how the plates are moving with each other…

Plate Boundaries:

1.DivergentThese plates are moving away from

each other.

Plate Boundaries:

2. Transform FaultThese plates are sliding along side

each other.

Plate Boundaries:

3. ConvergentThese plates are moving into each

other.

Convergent Boundaries:

• There are a couple of different things that can happen at this boundary because there are 2 different types of crust on Earth.

• There is continental crust (crust that is mostly above water: land)

And• There is oceanic crust...that is under the water.

• The continental crust is less dense and thicker than the oceanic crust… so what happens when the two different crusts collide at a convergent boundary???

Convergent Boundaries

A: Since the Oceanic crust is more dense it dives beneath the Continental crust

= SUBDUCTION ZONE (picture A)

Convergent Boundaries

• Continental–Continental collision (picture C)

The crust buckles UP and forms large mountains.

Geological FormationsAt each boundary different

geological formations (mountains, volcanoes, trenches, earthquakes, faults, etc.) occur because of the movement of the plates.

Lets look at what forms at each boundary…

Geological Formations – Divergent

Seafloor SpreadingMid-oceanic ridges and Volcanoes

Geological Formations – Convergent (NO subduction)

Large Mountains (in the middle of land)

Geological Formations – Convergent (WITH subduction)

Volcanoes, Coastal Mountains, Island Arcs, and Oceanic Trenches

Geological Formations – Transform Fault

Faults and Earthquakes

Let’s Find Some of These On a MAP…

• Just by looking at a 3-D map you can determine what type of plate boundary there is b/c of the formations that occur!!!

Let’s Review…• Convergent Subduction Zone

occurs at the Peru-Chile Trench and Andes Mts. between the NAZCA and SOUTH AMERICAN PLATES.

• Convergent (NO subd.) occurs at the Himalaya Mts. between the INDIAN and EURASIAN PLATES.

• Transform Fault occurs at the San Andreas Fault (in California!!!) between the NORTH AMERICAN and PACIFIC PLATES.

• Divergent (Mid-Oceanic Ridge) occurs at the Mid-Atlantic Ridge between the NORTH AMERICAN and AFRICAN PLATES.