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Download Earth`s Interior and Plate Tectonics
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Earth’s Interior and Plate Tectonics Earth’s Composition: •Not just solid rock •Distinct layers •Each layer has certain physical properties 3 Main Layers when dividing them by their composition ►Crust ►Mantle ►Core Crust ►Outermost layer ►5 – 100 km thick ►Thinnest layer ►High in Silicon and Oxygen (makes rocks called silicates) ►< 1% of Earth’s mass Continental Crust ►Average thickness of 30 km ►Composition similar to granite Oceanic Crust ►Average thickness from 5-8 km ►Composition similar to basalt Oceanic crust is more dense than Continental crust Mantle ►Between crust and core ►Extremely thick and 66% (2/3) of Earth’s mass ►Large amounts of Calcium and Magnesium The Core ►33% (1/3) of Earth’s mass ►2 separate layers ►Mostly Iron and Nickel There are 5 layers when we divide them up by their physical properties ►Lithosphere ►Asthenosphere ►Mesosphere ►Outer Core ►Inner Core Lithosphere ►Made of the Crust and Upper Mantle ►Rigid, solid, cool ►About 150 km thick Lithosphere is broken into tectonic plates Asthenosphere ►Upper part of the mantle ►1-5% liquid rock ►Flows like putty, or plastic (very viscous) ►Lithosphere (tectonic plates) slide around on the asthenosphere Mesosphere ►The middle layer when dividing them up into 5 parts ►Same as the mantle ►About 1% liquid ►High viscosity ►Flows very slowly Outer Core ►Liquid layer ►Hot, but not as hot as the inner core ►Solid Inner Core and most dense layer o ►6,000 Celsius (hotter than Sun’s surface) ►So why is it solid? Some plates contain both continental and oceanic crust How do we know what the Earth’s interior looks like? Deepest hole drilled: ►12.2 km into the earth ►Kola Pennisula, Russia 1984 Seismic Waves ►From earthquakes ►There are 3 different types ►Travel through earth’s layers ►Transmission depends on phase (density) of the layer But why do tectonic plates move? Convection Currents The next time you heat anything like soup or water in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the asthenosphere they also move the crust. The crust gets a free ride with these currents, like the cork in this illustration. Dynamics of the mantle…