Differentiated earth

Earth

• Size

• Main Characteristics of the surface and interior

Statistics about the Earth

• Shape of Earth is nearly spherical(only just 40 miles difference in

circumferences)Because earth spins

Circumference is about 24,000 miles aroundRadius is about 3800 milesDiameter 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

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% nitrogen21 % oxygen1% other gases (including CD)

The Pacific ocean

Largest ocean

at present

64 million square

Miles

It would take 244

States of Texas

To cover the same

area

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)

Shape of Earth

• Oblate Spheroid

Column Demo

Lead questions

1) 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

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

Density determines the structure inside the Earth

Formation of layers

Cross section diagram

ZONES of the EARTH

1) Inner core2) Outer Core3) Lower Mantle4) Asthenosphere5) Lithosphere6) Crust (ocean and

continent)7) Hydrosphere8) Atmosphere

9) Magnetosphere

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)(this is a second definition)

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

• 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 29.5% of the Earth’s total

Mantle

• Thickest section of the interior of the earth

• The entire mantle Comprises 80% of Earth volume

• The mantle is further divided into 3 important subsections

--Lower Mantle (thickest section)– Asthenosphere– Lithosphere

Mantle subsectionsLithosphere

topmost layer of mantle (nearest to surface of Earth)solid, brittle100-200 miles thick

Asthenosphereunderlies the lithospheretexture like silly-putty, bends under pressureSimilar thickness as lithosphere

Crust

• The layer of the earth next to the surface• Very thin

– Oceanic 2-4 miles– Continental 40-65 miles

• The least dense of all layers– Ocean crust is denser than continental crust

• 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

Magnetosphere

• 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

• Thinnest:

• Thickest:

• 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)

QUESTIONS ABOUT HOW WE KNOW THAT THE EARTH IS DIFFERENTIATED

How do you think we know anything about the inside the

earth?

• Have we gone down and looked at each layer?

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

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 and indirect evidence from seismic waves.

• Using data from seismic waves produced by

earthquakes, geologists have learned that Earth’s interior is made up of several layers.

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

Different form of Echolocation

• Using seismic waves• Created by vibrations of the Earth• Using time to indicate distance and type of

material

• Causes of vibration• Natural: Earthquakes• Man-made: Gunshots

Seismic wave speed

• Faster in lithosphere than crust

• Slows down in Asthenosphere

• Increases through the rest of the mantle

• Drops off in Outer CoreNo S waves

Shadow Zone

Using an air-gun to create seismic waves

A cross sectional map using info from seismic waves

Two types of Seismic waves used

• P-waves

Primary-pressure wave (longitudinal)

Fastest wave

Some of the wave goes through all

material, some reflects back

Changes direction at each boundary

S-waves

• 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 ?

Answer

• 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.