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Structure of the Earth

 

Have you ever wondered what the planet Earth is made of?  Think of a boiled egg.  An egg constitutes the thin shell, the white and the yellow yolk in the middle.  Like wise the earth is made up of the thin outermost layer called the crust, the innermost part called the core, and the part in between them called the mantle.

 

A scientific illustration shows a three‑dimensional view of Earth with a large wedge removed to reveal the planet’s internal layers. The outer surface displays oceans and landmasses. Inside the cutaway section, four distinct layers are shown in bright colours with labels and distance measurements. The crust, the thinnest outer layer, is depicted in a dark brown colour with a label indicating a thickness of 7–60 km. Beneath it, the mantle is shown as a thick, swirling orange‑red layer labelled 2,845 km deep. Further inward, the outer core appears as a vivid, molten orange region labelled 2,280 km deep. At the centre, the inner core is represented as a bright yellow sphere, labelled 1,310 km deep. Black lines connect each label to the corresponding layer. At the top of the image, the text “STRUCTURE OF THE EARTH” appears in bold capital letters.

Structure of the Earth – Cross Section Diagram

 

 

An educational diagram compares the internal structure of Earth with that of a hard‑boiled egg. On the left, a model of Earth sits on a wooden stand. A vertical slice reveals three internal layers: a thin brown crust, a thick orange‑red mantle, and a bright yellow‑white core at the centre. Each layer is labelled with red lines pointing to “Crust”, “Mantle”, and “Core”. On the right, a hard‑boiled egg stands upright in a light wooden egg cup. The egg is also sliced vertically to expose its interior. The white outer shell is labelled “Shell”, the solid white interior is labelled “White”, and the yellow yolk in the middle is labelled “Yolk”. Both the globe and the egg are shown against a blurred classroom background with a green chalkboard. A heading above the images reads: “The Earth’s structure is similar to that of an egg.” Comparison of Earth's internal layers and an egg's structure

 

 

At the start, the early earth seemed to have heated up.  The centre became molten, and convection currents developed.  The lighter materials floated towards the surface forming the brittle crust. The crust is very thin approximately 40 km or so thick.  Together with the top part of the mantle, it formed the hard slabs known as lithosphere.  The continents are set in these slabs.  The lithosphere is divided into 2 parts, the oceanic (Sima) and continental crusts (Sial).

 

Sima , the floor of the deep oceans, is about 8Km thick and is composed of relatively dense rocks like basalt.  Sial, however, is  much thicker, averaging 32Km, and is made up of relatively  light material, for example granite.

 

The denser materials such as iron and nickel sank to form the core.  The coreis made up of two parts, the inner and outer core.  The inner core is solid, made up of iron and nickel. This is where the Earth's magnetic field originates.  The outer core is liquid and it is extremely hot, about 3000ºC.

Between the core and the crust, the intermediate zone forms the mantle.  This is liquid but very viscous and is made up of molten rocks, called the magma.

Radioactive decay in the inner core creates all the heat inside the Earth.  This heat causes the convection currents which cause the plates of the crust to move.

 

A detailed 3D cross‑section model of the Earth displays the crust, ocean, mid‑ocean ridge, trench, mantle, asthenosphere, and core. The upper layer shows blue ocean water and sections of the rocky crust on either side. A raised mid‑ocean ridge appears at the centre with white arrows on the surface indicating the outward movement of tectonic plates. On the right side, the crust dips sharply downward into a deep trench. Below the crust, the mantle and asthenosphere are shown in glowing orange and red tones. Multiple curved arrows within these layers represent convection currents, forming looping paths: hot mantle material rises from deep regions near the core, moves outward beneath the crust, then sinks back down near the trench. At the bottom, the bright yellow core emits an intense glow, highlighting the heat source that drives the circulating currents. The model rests on a base labelled “Earth’s Convection Currents – A 3D Model”. Convection Currents

 

Continue... Continental Drift

 

 

🌍 Knowledge Check: Structure of the Earth

How well do you know what's beneath your feet? Test your knowledge on the Earth's layers.

1. Which layer of the Earth is the thinnest?

2. The Earth's core is primarily made of which two metals?

3. Which layer is described as 'semi-liquid' rock that can flow?

4. Why is the Inner Core solid even though it is extremely hot?

5. What is the approximate temperature of the Earth's Inner Core?

Click to Reveal Answers
1. The Crust (Only 5km to 70km thick).
2. Iron and Nickel (These heavy metals sank to the centre when Earth was formed).
3. The Mantle (The thickest layer, consisting of slow-moving magma).
4. Extreme pressure (The pressure is so great that atoms are forced together into a solid).
5. 5500°C (About the same temperature as the surface of the Sun).

 

Tags:Earth structure, Mantle, Crust, Core, Convection currents

 

 

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