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## Structure of The Earth ### Did You Know? - Scientists have identified two major discontinuities, the **Moho discontinuity** (named after the scientist **Andrija Mohorovičić**) and the **Gutenberg discontinuity**. - The **Moho discontinuity** is the boundary between the Earth's crust and mantle....

## Structure of The Earth ### Did You Know? - Scientists have identified two major discontinuities, the **Moho discontinuity** (named after the scientist **Andrija Mohorovičić**) and the **Gutenberg discontinuity**. - The **Moho discontinuity** is the boundary between the Earth's crust and mantle. - The **Gutenberg discontinuity** was discovered by the scientist **Beno Gutenberg**, who discovered the boundary between the mantle and the core. ### Core: - The core is the innermost layer of the Earth and is also known as the **Barysphere**, Greek for "heavy," derived from the Greek word *barus*. - The core’s average radius is approximately 3,500 km and it’s composed mostly of liquid nickel (Ni) and iron (Fe), earning it the name “nife.” - The outer core is about 2,200 km thick with temperatures ranging from 4,500°C to 5,500°C. It’s so hot it remains in a molten state. The average density ranges between 5g and 13g per cubic centimeter. - The inner core has a radius of approximately 1,220 km and is solid despite temperatures of 5,200°C due to the immense pressure from the surrounding layers. ### Crust: - The Earth’s crust is the outermost layer of the earth’s surface and it exists in a solid state. - It is composed of hard crystalline rocks, such as igneous rocks, and is the thinnest layer. #### Continental Crust: - Forms large landmasses. - It is the upper part of the crust. - Its composition is primarily made up of silica (Si) and aluminum (Al), and is known as **sial.** - The siall contains the soil that supports the growth of plants. #### Oceanic Crust: - Is a relatively thin layer that lies beneath the ocean basin. - Its composition is primarily made up of silica (Si) and magnesium (Mg), and is known as **sima.** - Compared to the oceanic crust, the continental crust is thicker, with an average thickness of around 35 km. - The thickness of the continental crust is greater in mountainous regions, such as the Himalayas, where it can be as much as 70 km thick. - The average density of the crust is about 3g per cubic centimeter. - The Earth’s crust provides us with valuable resources like coal, as well as minerals like iron ore, among other valuable resources. ### Mantle: - Beneath the Earth’s crust lies the mantle, which is divided into two layers: the **upper mantle** and the **lower mantle**. #### Upper Mantle: - It extends from the **Moho Discontinuity** to a depth of 700 km and is composed of solid rocks that are cooler than the lower mantle. #### Lower Mantle: - It extends from 700 km to 2,900 km. - It’s denser and hotter than the upper mantle. - From 100 km to 410 km, the mantle is partially molten.