Transcript ppt
Layers of the Earth Crust Mantle Core Why do we have these layers? As the Earth cooled the heavier, denser materials sank to the center and the lighter materials rose to the top. Because of this, the crust is made of the lightest materials (rock- basalts and granites) and the core consists of heavy metals (nickel and iron). CRUST The outermost layer of Earth Composed of eight major elements: Oxygen Calcium Silicon Sodium Aluminum Potassium Iron Magnesium Composed of 2 major rock types: -Basalt (Ocean Crust) -Granite (Continent Crust) CRUST 3 – 5 miles thick in the oceans (Oceanic Crust) 5 – 25 miles thick in the continents (Continental Crust) -The crust of the Earth is broken into many pieces called plates. -The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere. MANTLE The largest layer of Earth, directly above the outer core Composed of: - Silicon - Iron - Oxygen - Magnesium Divided into: - Upper mantle (Part of the Lithosphere) - Lower /Middle mantle (asthenosphere) MANTLE 1800 miles thick Composed of very HOT, dense rock - Temperatures range from 1600°F to 4000°F!! - Convection currents in the lower/middle mantle move the plates. * Plates float on the Convection Currents A cycle that is believed to move the plates Caused by magma heating, rising, then cooling and sinking, and then heating, rising, cooling and sinking, and repeating the cycle over and over. CORE Located at the center of the Earth Divided into two parts: INNER CORE OUTER CORE OUTER CORE - 1400 miles thick - SO HOT that everything is in the liquid state! - Temperature ranges from 4000°F to 9000°F - Above the inner core - Liquid - Made mostly of iron and nickel INNER CORE - 800 miles thick - Temperature and pressure are VERY strong! - Temperatures may reach over 10,000°F (hotter than the sun!) - Solid and dense - Made mostly of iron What is the pressure like? The pressure is so great that you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth!!!!!!