8th Grade Dynamic Earth U4L1 Earth’s Layers

Earth’s Compositional Layers Crust Outermost, solid layer Made of oxygen, silicon, aluminum 2 types – continental and oceanic Ocean has twice as much iron, calcium and magnesium Oceanic is denser than continental, but continental is thicker Mantle Between core and crust Hot, flowing, solid rock Denser than crust More magnesium, less aluminum and silicon than crust Convection currents Cooler rock sinks, warmer rock rises Core From below mantle to center of earth Made mostly of iron and some nickel Densest layer – 1/3 earth’s mass Less oxygen, silicon, magnesium and aluminum than mantle *3 layers based on chemical composition – crust, mantle and core *Layers made of different mixtures of chemicals Deepest Hole on Earth (Sci Show)- https://www.youtube.com/watch?v=zz6v6OfoQvs

Earth’s Physical Layers Divided by physical properties including – solid / liquid, how layer moves, how layer transmits waves Lithosphere Outermost, rigid Made of crust and rigid part of mantle Divided into tectonic plates Asthenospheres Weak/soft mantle Rock Flows slowly Tectonic plates float on top Mesosphere Strong lower part of mantle Flows more slowly than asthenosphere Outer core Liquid (molten metal!) Beneath mantle, surrounds inner core Inner core Solid, densest Goes from bottom of outer core to center – center is 6,380 km beneath surface! NOVA scienceNOW | NOVA Short | Journey Through the Center of the Earth (Neil DeGrasse Tyson) - https://www.youtube.com/watch?v=wuHau1LTH8Y