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