Articles/Science/Other/Structural Zones of the Earth

1) The Inner Core - The inner most section of the Earth is called the inner core, it is basically the round center of our planet. This gigantic sphere is over 2700Km in diameter and is composed of iron and nickel. Despite having a temperature between 4000-6000 degrees Celsius, this giant mass is a solid, due mainly to its density and the pressure of our planet.

2) The Outer Core - The outer core is the outer layer that surrounds the inner core. This layer is also composed of Iron and Nickel but unlike the inner core, this layer is in a molten state. These liquid walls are over 2300Km thick and are constantly rotating and flowing around the inner core. The temperature here is slightly lower than the inner core at a temperature of 4000 degrees Celsius.

3) The Mantle - The next layer outward is the mantle. This layer is the largest of all the earths structural zones, being around 2900Km thick, and makes up about 70% of the Earth's volume. It is mainly thought of as a hard shell made of rock that encloses the Earth's core's and which lies just beneath the Earth's crust. Despite being classified as one zone, the mantle contains two of its own sub-zones, which are significantly unique from one another.

3A) The Asthenosphere - This is the upper most section of the mantle. It covers the top 250Km of the Mantle which boundaries the crust. Temperatures here can be as low as 100 degrees Celsius, but increases as you move further into the mantle towards the cores. Whats real unique about this layer is its physical and structural properties. This layer is neither solid or liquid but behaves like a plastique.

3B) The Lower Region - Oddly enough the lower region of the mantle doesn't have a name and is just referred to by its position. It consists of the other, lower 2650Kmof the mantle, and its properties are basically the general mantle properties listed above. Temperatures here range from 4000 degrees Celsius near the cores, to slightly above 100 degrees near the asthenosphere.

4) The Mohorovicic Discontinuity - This layer is often called the "Moho" and forms the boundary between the Astenosphere and the Earth's crust (lithiosphere). Its position between about 5Km beneath ocean ridges to approximately 75 km beneath continental crust. It is classified mainly do to its unique set of properties. Here scientists have measured rapid increases in the velocity of Earthquake waves.

5) Lithosphere - The lithosphere is the outer shell of the Earth, also known as the 'crust'. It is solid, rigid, and composed mainly of rock and similar materials and minerals. The lithosphere includes the ground we walk on, the surface of the Earth, down about 150Km continental or 70Km oceanic to the mohorovicic discontinuity. The lithosphere 'floats' on the asthenosphere, and do to its shell like nature, is generally brittle and has broken into several large fragments. These fragments are also known as 'tectonic plates' which float and push slowly across the Earth.

This article was written by Ryan Woodford