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Introduction Sometimes people may forget or take for granted how lucky we are that Earth is so suitable for human life. Let’s find out more about our Earth by looking at: The Four Main Regions of the Earth How seismic waves tell us about Earth’s interior What it means to say the Earth is differentiated The Theory of Tectonics Earths Atmosphere
Four Main Regions of the Earth Crust Mantle Outer Core Inner Core
Interior of the Earth Core- consists of a solid inner core and a liquid molten outer core. Mantle- Rocky material containing the minerals silicone and oxygen Crust- Continental crust is made mostly of granite while Ocean crust is made of basalt. The lowest density rock is found at the crust while the highest density is found at the core
Seismic Waves Seismic waves are waves of energy that pass through the Earth as a result of an Earthquake for example. P waves (primary waves) travel fastest and are produced first by an earthquake. P waves can travel through liquid and solid material. S waves (secondary waves) follow and do not travel through liquid.
Application Scientists can use seismographs to record seismic waves and learn about the interior of Earth. After a volcano at some point the waves hit the outer core and because the outer core is liquid only the p waves can travel through and the s waves are stuck.
Differentiation The Earth is made up of layers of different materials. This is due to differentiation. The Earth was once hot enough inside that it caused the interior to melt so that materials of higher density sank to the center and less dense materials went towards the surface.
How did the Earth become so hot? Two major reasons explain the Earths heat. 1. Planets were hot because of the process of formation. Colliding planetestimals deposited large amounts of energy that turned into heat. 2. The metal and rock that make up the Earth contain radioactive elements that when decaying produce heat.
Plate Tectonics Earths rocky outer crust is not solid but instead broken up into huge plates that sit on top of the mantle. The theory of plate tectonics explains the movement of Earths plates and the reason why we have earthquakes, volcanoes, mountains, trenches and many other geological features.
Plate Tectonics Continued… At the boundaries of plates they may separate from one another, collide, slip past one another, and slip laterally.
Troposphere We live in the troposphere which is the lowest layer of Earth’s atmosphere.
Earths Atmosphere Earths Atmosphere today consists of: 78% nitrogen (N2) 21% oxygen (O2) Small amounts of other gases Our atmosphere provides the air we breathe and the pressure that allows liquid water to flow
Earth’s Early Atmosphere Earth’s original atmosphere consisted of volatile gases such as Carbon dioxide, Water Vapor, Methane, and Ammonia. How then did we come to have the atmosphere that allows human life now?
Earth’s Changing Atmosphere When the Earth had cooled the water vapor had condensed and formed our oceans. Photosynthesis reduced the carbon dioxide level and increased oxygen that is necessary for all life. Carbon dioxide was also trapped inside rocks Volcanic eruptions released nitrogen into the air through a process called outgassing.
Conclusion Our Earth is a complex planet that has grown and evolved since its formation millions of years ago. Next week we will compare Earth to other planets in order to understand further what makes it so unique.