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Differentiated earth. Earth. Size Main Characteristics of the surface and interior. Statistics about the Earth. Shape of Earth is nearly spherical (oblate spheroid) (only just 40 miles difference in circumferences) Because earth spins Circumference is about 24,000 miles around

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Differentiated earth

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Differentiated earth



Main Characteristics of the surface and interior

Statistics about the Earth

Shape of Earth is nearly spherical

(oblate spheroid)

(only just 40 miles difference in circumferences)

Because earth spins

Circumference is about 24,000 miles around

Radius is about 3800 miles

Diameter 7600 miles

Distance between New York and Los Angeles is 2400 miles

Trip = 1/10 around the world

= 2/3 to the center of the earth

Earth facts

Relatively smooth for the scale

Highest mountains are 5.5 miles from sea level

Deepest trenches about 7 miles below sea level

Inside the earth?

Deepest that man has traveled into the earth?

A couple of miles down in the gold mines of South Africa 1 degree for every 33 m

Without air conditioning it would be around 160-170°F

With air conditioning it is 100 degrees with a 100% humidity

South African Gold Miner

Facts of Earth

71 % of Earth is covered by water

97% of that water is salty

Air we breathe at this point in earth’s history is made up of

78% nitrogen

21 % oxygen

1% other gases (including CD)

The Pacific ocean

Largest ocean

at present

64 million square


It would take 244

States of Texas

To cover the same


Trash in the ocean

How hot is the Earth?

Up to 140° F

Down to -100°F

Black Smoker Vent at the bottom of the ocean (500°F)

How do we know what is in the Earth if we have not been there?

  • Rocks that have been pushed up to the surface

  • Seismic waves (energy released from Earthquakes)

Info from Seismic waves

Can tell the texture of the rock through interpretation of the speed of seismic waves

Seismic waves move faster in more dense material

Certain seismic waves can not travel thru any liquid

Shadow Zone

How is the Earth (interior and exterior ) organized?

Column Demo

Lead questions

If you could drill to the center of the Earth, would the rock you drill through be the same all the way down? Explain your answer

Looking at the column of material created in the graduated cylinder, what property make allows separation between materials?

Density determines the structure of the Earth

Formation of layers


1) Inner core

2) Outer Core

3) Lower Mantle

4) Asthenosphere

5) Lithosphere

6) Crust (ocean and continent)

7) Hydrosphere

8) Atmosphere

9) Magnetosphere

Cross section diagram

Includes atmosphere

Main difference between layers

Density of material, which is determine by Composition of material

Temperature of material

Characteristics of the material

Definitions of spheres

Biosphere: Region where living organism exist, includes portions of the other spheres

Atmosphere (Region of air)

Hydrosphere (Region of water)

Lithosphere (Region of solid earth)

Layer details

Inner Core

Solid Metal, nickel and iron

Under incredible temp and pressure

Pressure on atoms in core from surrounding atoms keeps it solid

Around 1000 miles thick in diameter (1700 km)

Outer core

Nearly same composition as the inner core

Less heat and pressure

Liquid (too much pressure to turn to gas)

The movement of the Iron liquid, generates the Earth’s magnetic field

Slightly thicker than inner core

The volume occupied by both cores is about 25% of the Earth’s total


Thickest section of the interior of the earth

The entire mantle Comprises 75% of Earth’s volume

The mantle is further divided into 3 important subsections

--Lower Mantle (thickest section)



Mantle subsections


topmost layer of mantle (nearest to surface of Earth)

solid, brittle

100-200 miles thick


underlies the lithosphere

texture like silly-putty, bends under pressure

Similar thickness as lithosphere


The layer of the earth next to the surface

Less than 1% of volume

Some books consider crust as part of mantle

Very thin

Oceanic 2-4 miles

Continental 40-65 miles

The least dense of all layers

We have never drilled all the way through the crust

Differences between oceanic crust and continental crust

Continental crust is generally thicker, less dense and older than ocean crust

Continental crust has a higher % of silicon (a less dense material)

in its composition

  • Hydrosphere: Oceans

  • Atmosphere: Air

  • Some elements are so light that the pull of gravity does not keep them in the atmosphere


The region occupied by only the Earth’s magnetic field

Extends beyond the atmosphere into space

Northern lights

May be caused by the movement of the Earth’s liquid core

There may be another source of magnetic field

Both Sun and Moon have magnetic fields

Sun contains very little iron

Moon does not have a liquid core

Special characteristics of certain layers



Hottest, most pressure

Composed of Liquid:

Texture like silly-putty, because of pressure and temp:

Least dense:

The Moho Discontinuity

The boundary between the crust and the lithosphere

Named for a Croatian scientist with a last name of Mohorovicic

The seismic waves travel much faster in the mantle than crust (denser material)


How do you think we know anything about the inside the earth?

Have we gone down and looked at each layer?

Deeper into the earth

About 20-40 km down = 350 ° F,

the temperature you bake a cake

About 1000-1200 miles down = 2300 ° F

At the center of the Earth = up to 11,000 °F

In other words, 110 times more hot than the hottest summer day you have ever experienced

Geologists have used two main types of evidence to learn about Earth’s interior:

direct evidence from rock samples

indirect evidence from seismic waves.

Seismic wave speed

Faster in lithosphere than crust

Slows down in Asthenosphere

Increases through the rest of the mantle

Drops off in Outer Core

No S waves

Using an air-gun to create seismic waves

A cross sectional map using info from seismic waves

Two types of Seismic waves used


Primary-pressure wave (longitudinal)

Fastest wave

Some of the wave goes through all

material, some reflects back

Changes direction at each boundary


Secondary, shear

Slower than P-waves

Can not go through liquid

Info from Seismic waves

Can tell the texture of the rock through interpretation of the speed of seismic waves

Seismic waves move faster in more dense material

The s-waves can not travel thru any liquid

How did the Earth get layered ?


After enough material from the nebula dust cloud clumped together, the temperature inside the clump increased enough to melt it.

When melted, the heavy material settled towards the core, lighter material rose to the surface.

Another source of internal heat came from radioactive decay of materials. This still continues to today

Scientists think that movements in the liquid outer core create Earth’s magnetic field. Because Earth has a magnetic field, the planet acts like a giant bar magnet.

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