INSIDE OUR EARTH – Amazing Facts & Scientific Insights

 🌍 INSIDE OUR EARTH – Amazing Facts & Scientific Insights

Comprehensive Note for Class 7 CBSE Geography – Chapter 2
Student: Subhangam

💡 INTERESTING FACTS ABOUT THE EARTH’S INTERIOR

While we know the Earth has layers like an onion, scientists have never actually seen its center. Most of our knowledge comes from indirect studies, such as earthquakes, volcanic eruptions, and geological research. Here are some fascinating facts to help you understand the Earth better:

🔎 1. How Deep Can We Go into the Earth?

• The deepest mine in the world is located in South Africa, and it reaches a depth of about 4 kilometers. This mine is mostly used to extract gold.

• In the quest for oil and natural gas, engineers have drilled as deep as 6 kilometers into the Earth. However, this is still a very small part compared to the full depth of the Earth.

• To reach the centre of the Earth, one would need to dig around 6000 kilometers deep, especially if starting from the ocean floor.
  ➤ But scientifically, this is not possible due to extreme heat and pressure inside the Earth.

🌐 2. Volume Distribution of the Earth’s Layers

The Earth’s volume (the total space it occupies) is divided unequally among its three main layers:

Layer	Volume % of Earth	Notes
Crust	1%	Very thin and forms the surface layer
Mantle	84%	Thickest layer made of semi-solid rock
Core	15%	Innermost and hottest part of the Earth

👉 Although the crust is the only layer we live on, it forms just 1% of the Earth’s volume!

🌍 3. Radius of the Earth

• The radius of the Earth (distance from the surface to the center) is approximately 6371 kilometers.

• This means that if you could dig a tunnel straight through the Earth, it would be about 12,742 km long from one side to the other!

📜 WORD ORIGIN (ETYMOLOGY) OF GEOLOGICAL TERMS

Understanding the origin of words helps us understand their true meaning and use:

Word	Origin Language	Original Meaning
Igneous	Latin – Ignis	Fire (formed from molten magma)
Sedimentary	Latin – Sedimentum	Settle down (formed from layers of deposited materials)
Metamorphic	Greek – Metamorphose	Change of form (rocks that have changed due to heat and pressure)
Fossils	Latin – Fossilis (to dig)	Remains of dead plants and animals trapped in rocks

🦴 FOSSILS – WINDOWS TO THE PAST

• Fossils are the preserved remains or impressions of dead plants and animals that got trapped inside layers of rocks millions of years ago.

• They help scientists understand ancient life, the age of rocks, and how the Earth’s surface has changed over time.

✅ KEY TAKEAWAYS

• Even the deepest mines and boreholes reach only a tiny portion of Earth’s depth.

• The mantle takes up the largest portion of Earth’s volume (84%).

• Scientific names like igneous, sedimentary, and metamorphic come from Latin and Greek, revealing how they form.

• Fossils are not just dead remains — they are clues to Earth’s ancient history!