Planet Earth is one of the unique planets in the Solar System because of the presence of abundant water resources to sustain life. It may seem like the Earth is made up of a single layer of a big solid rock. However, that is not true. The Earth is actually composed of several parts and layers, some of which are constantly moving. The Earth is divided into several layers including the core, mantle, lithosphere, and crust. Each of the layers has unique properties. Here is a brief overview of the major layers of the Earth.
The crust is the outer layer of the Earth. It is the thinnest layer of the earth compared to the other layers. Its thickness varies from 5 kilometers in the ocean floor to about 70 kilometers on the land surface. The crust is subdivided into huge plates that float into the next layer of the earth (mantle). The plates are constantly moving but at a slow pace. When the plates grind against each other, earthquakes occur but when they collide the mountains are formed. The theory explaining the movements of plates is often referred to as plate tectonics. The Earth’s crust is made up of several elements including oxygen, aluminum, silicon, calcium, iron, sodium, magnesium, and potassium.
The mantle is under the crust and is approximately 2,890 kilometers deep. It is by far the thickest layers and accounts for 85% of the volume of the Earth. The layer can be divided into upper and lower mantles. The great pressure on the lower mantle makes it completely solid while the upper mantle, also known as the asthenosphere, is liquid and flows as a convection current. The mantle is mainly made up of silicate rocks that are rich in iron and magnesium. Because of the intense heat, the silicon rocks rise. The rocks then cool and sink down to the core. The heating, cooling, and sinking of the rocks are thought to be responsible for the tectonic movement.
The Earth’s core is divided into inner and outer cores. Both cores are mainly made up of iron and nickel. The difference between the inner core and the outer core is that the mineral in the inner core is solid while those in the outer core are liquid. The inner core is as hot as the sun but because of the pressure from the weight of the earth pushing down on it, it cannot melt. However, the outer core has less pressure on it leading to the melting of minerals. The liquid is slow moving and is responsible for the Earth’s magnetic field. The North and South poles also exist because of the liquid outer core.
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