Earth’s Interior and Plate Earth’s Interior and Plate TectonicsTectonics

Integrated ScienceIntegrated Science

Ch 12Ch 12

This is how the continents This is how the continents formed….formed….

• http://www.youtube.com/watch?v=TzzGPfVx32M&list=PLABDC7B24FAFE33FD

The Earth is like a parfait, it has layersThe Earth is like a parfait, it has layers

• If you cut the earth in half, it would look very much like a parfait, with different layers and compositions based on density

• The earth has three main layers, the crust, the mantle, and the core

The CrustThe Crust

• We live on this layer• Its is cool, and made of

solid rock• Oceanic crust is thinner

and denser than continental crust.

• The crust is the least dense portion of the earth and only about 12-25 miles thick

The MantleThe Mantle

• Layer of rock that is denser than the crust

• About 1800 miles thick• Outer mantle is solid rock• Inner mantle the rocks

are extremely hot and bendable like gum (plastic)

The CoreThe Core

• The center of the earth

• Made mostly of iron and nickel

• The inner core is solid metal while the outer core is liquid metal

The Earth heats up with depthThe Earth heats up with depth

• At only 2 miles down the temperature increase to 120 F

• The core is much hotter than the mantle

• In the core, temperatures reach over 10,000 F

The earth heats up with depthThe earth heats up with depth

• The earth gets warmer towards the core because it contains so many radioactive isotopes

• These unstable isotopes are constantly breaking down, releasing huge amounts of energy, which in turn heat the earth

How do plates move?How do plates move?

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

Evidence #1: Evidence #1: The Pangea PuzzleThe Pangea Puzzle

• In the 20th century, Alfred Wegener noticed that eastern S.America fits into western Africa

• He also noticed that several of the other continents fit together like puzzle pieces

• He also found that fossil evidence showed that several of the same organisms are found on continents now separated by oceans

• He theorized that 250 million years ago all the continents combined to form the giant land mass he named pangea

How did this happen?How did this happen?

• The earth’s outer shell, called the lithosphere is made of the crust and upper portion of the mantle.

• This lithosphere is very rigid and consists of 7 large pieces and a few small ones that fit together like a puzzle

• These large pieces are called tectonic plates

Plate TectonicsPlate Tectonics• These plates fit together like puzzle pieces and

move in relation to each other• these plates move away, towards, or alongside each

other• Tectonic plates move about 6 inches per year

Divergent Divergent Plate Boundaries Plate Boundaries

• In some areas, the plates move away from each other

• When this occurs, hot liquid rock called magma rises and cools, forming new lithospheric rock

Convergent Convergent Plate BoundariesPlate Boundaries

• Less dense continental plate floats over more dense oceanic plate• This process is called subduction• As this more dense rock goes down into the mantle, it heats up

and melts• The magma rises and pushes up the crust, forming volcanic

mountains also earthquakes

• Subduction - two plates meet, the more dense plate (oceanic crust), dives beneath the less dense plate (continental crust)

Continental vs. ContinetalContinental vs. Continetal

• Same density so no subduction

• Builds non-volcanic mts.

• Earthquakes

Oceanic vs. OceanicOceanic vs. Oceanic

• Similar density, but subduction anyway

• Earthquakes, trenches,

• volcanic island arcs

Transform Fault BoundariesTransform Fault Boundaries

• These are areas where plates move along side one another

• As plates move, they can cause cracks in the lithosphere called faults

• As plates move along side each other at these faults, the plates cause a great deal of force and create earthquakes

RECAP RECAP

• Divergent Plate Boundaries– Divergent means plates MOVE AWAY from

each other

• Convergent Plate Boundaries– Convergent means plates MOVE TOWARD

each other

• Transform Fault Boundaries– areas where plates move along side one another

• like this or this •

• Earth is made of 3 main layers– Crust- cool, thin, made of rock, 10-25 miles

thick– Mantle, denser than crust, 2500 miles thick,

80% of earth’s volume: inner mantle solid rock, outer mantle bendable gummy rock

– Core- center of earth, made of iron and nickel, made of 2 layers: inner solid metal, outer liquid metal

• Pangea- 250 million years ago all the continents combined to form the giant land mass called Pangea

• Lithosphere (earth’s outer shell) is made of the crust and upper portion of the mantle.

• lithosphere -very rigid and consists of 7 large pieces (called tectonic plates) and a few small ones that fit together like a puzzle

• Plate Tectonics

• These plates fit together like puzzle pieces and move in relation to each other

• these plates move away, towards, or alongside each other

• Tectonic plates move 6 inches per year

Evidence 2: Evidence 2: BiogeographicalBiogeographical

Final viewsFinal views

• http://www.youtube.com/watch?v=QrQDXnnXOo4&feature=player_embedded#!