Lecture Notes: Inside Our Earth

Introduction

Presented by: Singh Rajput at Magnet Brains
Focus: Chapter on the economy inside our Earth, suitable for 7th grade Geography.

The chapter explores the interior of the Earth and discusses various layers and their compositions.
Importance of understanding geological structures for examination and science.

Crust
- Definition: The outermost layer of the Earth.
- Thickness: Approximately 35 kilometers under continental areas and about 5 kilometers under oceanic areas.
- Composition: Mainly silicates, aluminum, and minerals like copper.
Mantle
- Definition: The layer beneath the crust.
- Thickness: Extends from 35 kilometers deep to about 2,900 kilometers.
- Characteristics: Composed of semi-solid rock, it behaves like a thick fluid over geological time.
- Magma: The mantle contains molten rock that can lead to volcanic activity.
Core
- Definition: The innermost layer of the Earth.
- Composition: Mainly made of nickel and iron (NIFE).
- Radius: Approximately 3,500 kilometers, contributing to about 15% of the Earth's volume.

Three Major Types of Rocks:
1. Igneous Rocks: Formed from cooled magma.
  - Types: Intrusive (cools underground) and extrusive (cools above ground). Examples: Granite (intrusive), Basalt (extrusive).
2. Sedimentary Rocks: Formed from the accumulation of sediments.
  - Characteristics: Often contain fossils, formed through processes of compaction and cementation. Examples: Sandstone, Limestone.
3. Metamorphic Rocks: Formed from existing rocks changing due to heat and pressure.
  - Examples: Slate (from shale), Marble (from limestone).

Concept: The continuous process where rocks transform from one type to another.
- Processes Involved: Weathering, erosion, deposition, compaction, and metamorphosis.
- Cycle Stages:
  - Igneous rocks can become sedimentary through weathering and sedimentation.
  - Sedimentary rocks can transform into metamorphic rocks under heat and pressure.
  - Metamorphic rocks can melt to form magma, restarting the cycle.

Deepest Mine: The deepest mine in the world is located in South Africa, reaching depths of about 4 kilometers.
Earth's Radius: The radius of the Earth is approximately 6,371 kilometers.
Core Contribution: The core makes up 15% of the Earth's volume, while the mantle makes up about 84%.

Understanding the Earth's layers and rock types is crucial for geology studies.
Importance of studying these concepts for both academic purposes and comprehension of natural phenomena.

Official website: Magnet Brains for downloads and further reading on the subject.