Elements of the Earth

## Elements of the Geosphere

The geosphere can be described as the solid components of the Earth; including the composition of what is inside the Earth such as rocks and minerals, the landforms above and beneath the surface of the Earth (lithosphere), as well as the interior layers of the Earth. The processes that form and shape the Earth's lithosphere can be attributed to the movements caused by these interior layers.

The three main elements of the geosphere are the crust, the mantle, and the core.

The geosphere has varying processes responsible for its sustainment such as plate tectonic movement and the rock cycle.

### Layers of the Earth

#### The Crust

* The crust as we know it is the very ground we walk on. But in geological terms, the crust is defined as the thinnest layer of the Earth that makes up its surface and is situated above a denser layer called the mantle.
* The crust takes into account the continents of the Earth and the ocean floor, as well as the landforms and rock material found on and beneath the surface of the Earth.

* At the base of the crust lies an area known as the Mohovoricic discontinuity. This is a prominent area of seismic discontinuity which means that because there are changes in the physical and chemical properties within the Earth’s crust, there is abnormal behavior or irregular patterns of seismic waves.
* The crust along with the uppermost, brittle section of the mantle is called the lithosphere.

#### The Mantle

* The mantle of the Earth lies between the crust and the dense superheated core of the Earth.

* It is said that the mantle makes up 84 percent of the Earth and it is divided into three main parts; the upper mantle, the transition zone, and the lower mantle.

##### Upper Mantle

* The upper mantle is located from the lithosphere to a depth of 410 kilometers and is technically a malleable solid (clay-like/rubbery consistency). Due to its lack of rigidity, it contributes to tectonic activity.
* Also located within the upper mantle is the asthenosphere which basically is molten liquid that continuously rises and cools due to convection currents which increases tectonic activity on the lithosphere.

##### Transition Zone

* As depth increases, roughly between 410 and 660 kilometers below the crust, rocks within the transition zone of the mantle do not melt or disintegrate.
* Due to the increasing density and pressure, the rocks' structures are transfigured to become immensely denser.
* This is why subducted plates often do not sink into the lower mantle as they are less dense than the rock material found at the transition zone.

##### Lower Mantle

* This section lies deep beneath the Earth's surface, reaching a depth of approximately 2,700-2,900 kilometers below the lithosphere.
* Denser and immensely hotter than the other sections of the mantle, the lower mantle remains solid due to the constant pressure.

#### The Core

* The superheated ball of dense mass that lies at the center of the Earth; split into the outer and inner core.

##### Outer Core

* This layer is about 2,200 kilometers thick and consists of liquid iron and nickel.
* It is very low in viscosity and easily deformed which gives it its malleable nature.
* Temperatures within the outer core are between 4,200**°C** - 4,900**°C.**
* The churning of the metallic minerals within the outer core generates the convection currents that are responsible for the Earth's magnetic fields.

##### Inner Core

* Positioned at the center of the Earth is the inner core, with a radius of 1220 kilometers is this ball of superheated iron.
* Though the temperatures (approx. 5,200**°C**) within the inner core far surpass that of the melting point of iron, the pressure and density present prevent the iron atoms from transfiguring into a liquid state.