Section 4.1

• Vocabulary to know• Crust• Mantle• Core• Lithosphere• Continental crust• Oceanic crust• Asthenosphere• Mesosphere• Outer core• Inner core• Radioactivity

Earth’s interior…• Made up of:

– Crust, mantle, and core

Crust

• Crust-– Outermost and

thinnest layer of Earth.

– Relatively cool.• Two types:

– Oceanic crust• Crust beneath

ocean (2.5-4.3 mi thick)

• More dense– Continental crust

• Crust beneath continents (12-25 mi thick)

• Less dense

In between the crust and mantle… sort of…

• Lithosphere-– The thin outer shell

of the Earth.• Consists of the

crust and the rigid upper mantle.

• Asthenosphere-– Beneath

lithosphere (in the mantle).• Consists of slowly

flowing solid rock.

This Sucks!

Mantle

• Mantle-– Layer of rock between

Earth’s crust and core.

– More dense than the crust (which is why it’s beneath it).

– Makes up about 80% of Earth’s volume.

– Outer mantle-• Rocks mostly solid.

– Inner mantle-• Rocks easily deformed

Core

• Core-– Center of a

planetary body.– Composed of

iron (Fe) and Nickel (Ni).

• Two layers:– Outer core

• Liquid metal

– Inner core• Solid metal

Where is it the hottest?• The Earth gets hotter

as you go deeper!– Crust ( ~347o F)– Mantle (~2280o F)– Outer core (~7000o F)

• So hot that the rocks actually melt!

– Inner core (~10,800o F)• So hot that the rocks

melt BUT so much pressure that they remain a solid!

Why is the Interior so hot?• It contains

radioactive isotopes.– Uranium, Thorium,

and Potassium• Their nuclei break

up (decay) releasing energy as they become smaller nuclei.

• Earth is huge…so there is a lot of energy being released.

How to remember the 5 physical Structures of the Earth…in order

• Using the hand method

1st Layer

LITHOSPHERE

2nd LayerASTHENOSPHERE

3rd LayerWhat would three scared foreigners say if they don’t speak english and are trapped under two of Earth’s physical structures?

MESOSPHERE (ME SO FEAR)

4TH Layer

What was Lincoln know for saying?

Four SCORE and 7 years ago. (Outer)

5th Layer

These guys are???

INNER

Section 4.2 and 4.3

• Vocabulary to know• Plate tectonics• Continental drift• Alfred Weggener• Pangaea• Convection currents• Subduction• Sea-floor spreading• Mid ocean ridge• Rift valleys• Trench• Magnetic striping

PLATE TECTONICS

• Plate Tectonics- – theory that explains the

formation and movement of earth’s plates

• Continental Drift- – Alfred Weggener’s theory

that continents were once joined in a single supercontinent, which then broke into pieces that moved apart.

– Move 0.4 to 6.3 in. per year

Continental Drift

• How could a fresh-water animal (Mesosaurus) be found on two continents that are separated by an ocean?

• Could it be…

Evidence of Continental Drift

• …Continental drift!– Many fossils

matched up perfectly once the continents were put together.

– The continents also fit together like puzzle pieces.

– But how could continents move?

Scientists aren’t quite sure…

• …but they think it might be due to convection currents.

Water rises because it’s less dense… then cools and sinks as it becomes more dense.

Sea-floor Spreading

• Would you expect the middle of the ocean to be its deepest point?– Why or why not?

Ridges

At its peak, the mid-ocean ridge has a valley, also known as a rift…

What happens when plates run into plates?

• Mariana Trench – Lowest point on

Earth.• 35,798 ft below sea

level.

Mount Everest from space.Highest point on

Earth29,028 ft above

sea level.

Subduction

Subduction• Trench-

– as a plate sinks through a subduction zone, it bends forming a depression in the ocean floor.

• What is the deepest point in the ocean?

Subduction• Sea-floor spreading- creates new oceanic crust

at mid-ocean ridges.• Subduction- destroys old oceanic crust at

subduction zones.

Evidence

Evidence• Magnetic striping

– Tiny grains of magnetite in the rock of the ocean floor behave like little magnets.

– Align with orientation of the Earth’s magnetic field.

– Points north presently…• Not always the

case…