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Daniel Fischbach Physics 203-001 – Earth In Space 5/9/17 Created on: 9/15/04 Topic: The Interior of Earth Earth - 70% ocean – 30% land Why? Surface is of varying elevation Continental shelf – part of continent that is underwater Continental slope – Steep decrease in land to ocean floor Continental rise – Part of ocean floor that rises up towards continental slope Continents are made of granite, a low density rock Submerged parts of continents are made of basalt (higher density) Interior o Core – iron (iron porous silicates) and nickel – most dense Inner (solid) core Outer (molten) core o Mantel – silicate rocks and iron (iron rich silicates) – lower density than core Mesosphere – First layer Asthenosphere - Molten silicate rock Lithosphere - Solid (Rest of mantel + crust) o Crust – silicate – least dense History o Earth was molten o More dense materials sunk below (iron and nickel – became core) o Silicate rocks were buoyed up (floated) o This process when material is separated called differentiation All planets are differentiated Mars has a lot of iron on its surface and it rusted (that’s why Mars is red) Mars HAS differentiated itself Mars is smaller than Earth (less mass and gravity) less of a gravitational pull that is why iron is on the outside (did not differentiate itself as much as Earth did) Crust can be thick and thin (thin under ocean…thick makes the continents) We know about the interior of the Earth by seismic waves A wave is a propagating (traveling) disturbance A wave needs a medium to travel through (air, etc.) “How can you have a propagating distance when there is nothing to disturb damnit?!” Sound travels o Fastest – Solid o Medium – Liquid o Slowest – Gases Transverse wave – Disturbance is perpendicular to the propagation Longitudinal wave – Disturbance is parallel (or anti-parallel) to the propagation 840990950 Instructor: Libarid A. Maljian Page 1 of 3 Daniel Fischbach Physics 203-001 – Earth In Space 5/9/17 Standing wave – does not propagate Harmonics – how many turns at a time – travels, stops, and spins (http://www.physics.uiowa.edu/~umallik/adventure/music.htm) Seismic waves (from earthquake) travel (propagate) through the Earth (one rock causes other rocks to vibrate) Earthquakes are detectable on the other side of the Earth Pressure wave (P – primary wave – fastest) – rock exerts a force on another rock (pushes) Sheer wave (S – secondary wave) – rubbing up against while exerting force S waves are not able to propagate through liquid (or molten rock) (only through solid rock) 840990950 Instructor: Libarid A. Maljian Page 2 of 3 Daniel Fischbach Physics 203-001 – Earth In Space 5/9/17 Shadow zones – Cannot detect S waves in these areas Speed of the wave depends on the density of the medium Magnetosphere – magnetic field Created by molten outer core It protects us from solar winds Particles of sunlight get trapped in the Val Alan Belts and follow the paths to the poles and come together to create the Aurora Borealis Magnetic north is different from true north 840990950 Instructor: Libarid A. Maljian Page 3 of 3