The core, the mantle, and the crust are three main layers of the earth. Each of these layers has a unique temperature, thickness, and materials. To describe each layer in detail, I broke down the post into three sections, titling each with the names of layers of the earth.
The earth’s core is a 2,125-mile (3420 km) thick inner center of the planet. It is the hottest layer of the earth. Scientists estimated that the temperature in the core is around 10,800 F (6,000 C) hot. That indicates that the earth’s core is as hot as the sun’s surface.
The earth’s core is made of two layers: 1367-mile (2,200 km) thick outer core and 758-mile (1,220 km) inner core, both of which mostly consists of iron. If you look at most of the geological illustrations out there, you will notice that they depict the core as a molten ball of iron.
Interesting Fact: According to geoscientists, the core also holds abundant reserves of precious metals. There are an estimated 1.6 quadrillion tons of gold. That amount is enough to gild the whole surface of the earth at a 1.5 feet (46 cm) thickness. However, it is almost impossible to tap into the gold reserves given the distance and the nature of the core.
The layer that comes on top of the core is called the mantle. The mantle is 1802-miles (2900 km) thick layer of the planet which mainly composed of oxygen (44.8%), magnesium (22.8%), silicon (21.5%) and other materials such as iron, calcium, sodium, potassium, and aluminum. A mixture of all these elements contributed to the development of silicate rocks in the earth’s mantle such as olivine, pyroxene, and garnet.
The mantle has two layers: the upper mantle and the lower mantle. The upper mantle starts below the crust and goes all the way down to the border of the lower mantle. Its overall thickness is somewhere between 200 and 250 miles (322-402 km).
Compared to the upper mantle, the lower mantle is much hotter in temperature, and thicker in size. The temperature reaches about 7000 degrees Fahrenheit (3,870 degrees Celcius) in the lower mantle, especially near the core.
Interesting Fact: 84% of the earth’s total volume made up of the mantle. In other words, the mantle is the largest layer of our planet. Interestingly, abundant reserves of gold are also present deep within the mantle. However, modern drilling capabilities are not enough to extract gold out of the mantle.
The gold comes out of the mantle with the plumes of molten rock. For that reason, prospectors usually look for gold around volcanoes and ridges. As mentioned, gold comes to the surface with the molten rocks as magma and lava. Therefore, igneous rocks (rocks produced by volcanic activities) may hold gold.
The pressure in the mantle is 1.3 million times greater than that of the surface. Therefore, mantle holds a variety of minerals that we do see on the surface.
The crust is the outermost layer of the earth. Although we see the crust every day in every place, it is the smallest layer of the planet. The size of the crust only accounts for 1% of the earth’s total volume.
There are two types of crust: Continental Crust and Oceanic Crust. Compared to continental crust, oceanic crust is denser. And that is one of the reasons why continents are higher than the ocean floor. On the other hand, both oceanic and continental crusts are less dense than the mantle.
Some people vision that earth’s crust as apple skin. That is a reasonable comparison. We know that the skin of an apple is thinner than its inner part. Similarly, the crust is much thinner than the rest of the layer of the planet. The thickness of the crust varies depending on the areas: Oceanic crust is only 3-5 miles (8 km) thick, while the continental crust can reach somewhere around 25 miles (32 km) in thickness.
Primarily, two types of rocks make up the crust: Granite which is dominant in the continental crust, and basalt that covers the ocean floor. The basalt is developed from volcanic activities.
Interesting fact: Continents and ocean plates float across the underlying mantle. It is because the mantle is much hotter and denser than the crust. Also, heat coming from the core gives energy to mantle causing to move the crust. While earth’s crust moves, tectonic plates get stuck, slide, pull apart and collide with each other causing earthquakes.
Did you know? There was a supercontinent called Pangea, which existed between 299 and 180 million years ago. The Pangea included all of the continents we have today but due to the movement of earth’s crust, continents separated from each other and moved to the current day positions. If you look at the world map, you may notice that edges of the continent can come together like puzzle pieces.