Earth's+Structure

===In the case of the Earth, Primary (P) and Secondary (S) waves caused by earthquakes can travel through the Earth to other locations on the surface where they can be recorded. The time between the start and the arrival of the waves allows for locations of the layers and their densities. The denser the layer, the faster the waves travel through them.===

===S waves are a type of shear waves and can travel though solids but are unable to travel through liquids. The Outer Core is a liquid due to the fact that no S waves can travel through it unlike the P waves. The P waves slow down upon entering the Outer Core but speed up on entering the Inner Core due the change from a liquid to a solid.===

===It is deduced that the Outer Core and Inner Core are made of the dense and heavy metals, Iron and Nickel. During the formation of the Earth, it is believed that heavy materials sank to the center of the Earth with lighter materials floating to the surface. The Magnetic Field of the Earth is deduced to be caused by the motion or movement of the Outer Core's liquid Iron and Nickel.===

=== ===
 * = ===Earth Layer=== ||= ===Thickness=== ||= ===Material=== ||= ===Facts=== ||
 * = ===Crust=== ||= ===6-40 miles (10 km-65 km)=== ||= ===Composed of the minerals and rocks we have directly observed. (Rocks belonging to the Igneous, Sedimentary, and Metamorphic groups.)=== ||= ===Composed of all the rocks and minerals we have learned and tested.=== ||
 * = ===Mantle=== ||= ===1800 miles (2890 km)=== ||= ===A layer of the Earth that is composed of solid rock that has the consistency of slowly moving syrup. It takes up 84% of the Earth's volume.=== ||= ===The motion of the Mantle causes the Plates of the Crust to grow, move, and be destroyed. This movement of the crust plates results in the shape of the continents and the formation of mountain ranges and volcanoes. Plates can push against each other over time. A sudden slip between plates results in earthquakes.=== ||
 * = ===Outer Core=== ||= ===1408 miles (2,266 km)=== ||= ===Iron and Nickel (Liquid)=== ||= ===The temperature of this layer is similar to that of the Sun and causes the Iron and Nickel to be in liquid form. The movement of this layer of liquid Iron and Nickel is believed to cause the Earth's Magnetic field.=== ||
 * = ===Inner Core=== ||= ===Ball with a radius about 760 miles (1,220 km)=== ||= ===Iron and Nickel (Solid)=== ||= ===Though the temperature is close to that of the Sun, the pressure of the Earth upon the Inner Core results in the layer being squeezed into a solid.=== ||

===Crust is composed of separate pieces called plates. These plate change size and shape over vast amounts of time. The the pressures of the edges of where two plates push toward and away from each other is the cause of the formation of mountain ranges, location of volcanoes, and earthquakes.===

media type="youtube" key="ryrXAGY1dmE" width="560" height="315"

Video on Plate Movement over Time
media type="youtube" key="uGcDed4xVD4" width="560" height="315" Earthquake Why they Happen? media type="youtube" key="hlePrsXTGxQ" width="560" height="315"