7 layers of Earth you didn’t know about

The Earth’s interior is far more complex than what we are taught in school. Instead of just three layers- crust, mantle, and core- the Earth is made up of multiple intricate layers, each with its own unique characteristics and functions. These layers are continuously shifting, influencing everything from the movement of the continent to the magnetic field. The Earth is made up of a total of 7 layers which are- crust, lithosphere (crust and uppermost mantle), asthenosphere (upper mantle directly below the lithosphere), lower mantle, outer core and inner core. Let us take a closer look at these layers and functions they serve.

The crust is the thinnest and the outermost layer of our planet. On an average the layer is 25 miles (40 kilometers). This layer is further divided into fifteen major tectonic plates. These plates are rigid at the center and have geologic activities like earthquakes and volcanism, at the boundaries. By weight percent oxygen, silicon, aluminum, iron, and calcium are the most abundant elements in the Earth’s crust.

Lithosphere is made up of the crust and uppermost mantle, and is some 100 kilometers thick. The term "lithosphere" comes from the Greek words litho, meaning "stone," and sphaira, meaning "globe" or "ball". The tectonic plates that make up the layer move continuously at a rate of around 10 centimeters. It is the coolest layer of the Earth in terms of temperature.

The layer below the lithosphere, made up of the upper mantle, is known as the asthenosphere. While it is heavily vicious, it is also mechanically weak. The lithosphere-asthenosphere boundary (LAB) is identified by geophysicists as the point where there is a significant change in ductility—the ability of a solid material to deform or stretch under stress—between the two layers. This boundary in the upper mantle is typically marked by the 1300°C isotherm. Seismic waves travel relatively slowly through the asthenosphere.

The solid layer of Earth’s mantle lies between the crust and the core and is about 2,900 kilometers (1,802 miles) thick, making up 84% of Earth's volume and 67% of its mass. While the upper mantle is similar in composition to the crust, mantle rocks and minerals have more magnesium and less silicon and aluminum than the crust.

The region of the Earth that lies beneath the upper mantle and surrounds the outer core, is known as the lower mantle. located 400 to 1,800 miles below the Earth's surface, the layer is made entirely of rocks. The layer makes up for 55% of the Earth’s volume. It contains minerals like iron, and magnesium, and silicates like ferropericlase and silicate perovskite.

Situated between the mantle and the inner core, the Earth's outer core is a liquid layer of the Earth's core. It is mostly made up of iron and nickel, with little amounts of silicon and oxygen. The layer is about 1,400 miles thick and starts about 1,795 miles (2,889 km) beneath the Earth's surface and ends about 3,200 miles (5,150 km) beneath the surface. The Earth’s core is extremely hot as the heat from when the planet formed and the heat from the decay of radioactive elements gets concentrated here.

Inner core is the innermost part of the earth’s interior and one of the most functional parts too. The inner core is a key part of the geodynamo, which produces the magnetic field of Earth. The inner core is solid, despite its high temperature, due to intense pressure. Scientists believe that this layer is actually plasma, instead of pure solid.