earth as a system: earth: a unique planet 2.1 and 2.2 page 27

Earth as a System:Earth: A Unique Planet

2.1 and 2.2Page 27

Unique facts

Only planet with liquid water on the surfaceAtmosphere has a large percentage of oxygenOnly planet to support life

Earth basics

Third planet from the sun4.6 billion years oldMostly made of rock71% covered with liquid water

Earth from SpaceA blue sphere with white clouds

It is an oblate spheroidSpinning made the polar regions flatten and have an equatorial bulgeRelatively smooth

Earth’s Interior

Seismic waves have shown that Earth’s interior is layered

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Layers of the Earth

Earlier you learned about crust, mantle, and core

Here are some new terms

Look over only

Old Terms New Terms

CrustMantleCore

OuterInner

LithosphereCrust and upper solid mantle

AsthenosphereFlows with plasticity

MesosphereStrong lower part of the mantle

CoreOuterInner

Compositional &Structural Compositional &Structural ZonesZones

The Earth’s interior can be divided The Earth’s interior can be divided into compositional and structural into compositional and structural zoneszones..

CompositionalCompositional—What they are —What they are made ofmade of

StructuralStructural—how they behave—how they behave

Compositional zones are

CrustMantleCore

Structural Zones

LithosphereAsthenosphereMesosphereOuter CoreInner Core

CompositionalCompositional layers layersCrustCrustthin, solid, thin, solid, uppermost zone of uppermost zone of Earth.Earth. 

The crust varies from thin on the ocean floor

to thick at the mountain ranges

The crust is 10km thick under the oceans

Made of basalt

Continental crust is between 20-60 km thick

Made of granitic rocks that are less dense than basalt

Crust Thickness

The crust is the uppermost part of the lithosphere

Earth's Internal LayersAndrija Mohorovičić studied seismograms and discovered waves pick up speed at a certain depthEarth is layeredDrew a map of the upper boundary of Earth's mantle, Mohorovičić discontinuity

Cool geologists call it the

The Mantle3000 kilometers thick2/3 of Earth’s massHot iron-rich silicate rocks

CoreCore

The center of the EarthMade of iron and nickel   

Structural ZonesStructural Zones

Lithosphere

Narrow layerIncludes the Crust and Upper MantleThe Upper Mantle is cool and brittle

The lithosphere is very narrow and is rigid and brittle. It floats on the asthenosphere.The lithosphere is less dense

AsthenosphereAsthenosphere

Below the lithosphere is a less rigid layer called the asthenosphere

It is made of hot, iron-rich silicate It is made of hot, iron-rich silicate rocksrocks

Because of the intense heat and Because of the intense heat and pressure it behaves with pressure it behaves with plasticityplasticity

It is a It is a solidsolid that that flows flows like a liquidlike a liquid

Thermal convection currents occur here

Convection currents: hot less dense material rises, cools, and begins to fall again.

Mesosphere

The strong lower The strong lower part of the mantlepart of the mantle

Literally –the Literally –the middle spheremiddle sphere

Lies between the Lies between the asthenosphere asthenosphere and outer coreand outer core

The core is still the core.

The core has two parts:

the inner and outer cores

Outer core: liquid iron and nickelInner core: Solid iron, nickel, & sulfur

Magnetic FieldWhen a magnetic material rotates with another magnetic material an electric current is generatedThis current generates an electric field

The Earth's inner core spins within the liquid outer core producing a magnetic field

Magnetosphere

Earth’s Gravity Gravity is the force of attraction that exists between all matter in the universe

Newton described his Universal Law of Gravitation

The force of attraction between any two objects depend on both their mass and the distance between them

Weight and Mass

Weight is the measure of the strength of the pull on an object (a measure of gravitational force)Mass is the amount of matter in an object

There is a differenceMass stays the same, weight varies depending on where you are

An object’s weight depends on its mass and its distance from the center of the Earth According to the law of gravitation, the force of gravity decreases as the distance from the Earth’s center increases