Chapter 2 Inside Our Earth Summary with NCERT Solution

Class 7 - Social Science- NCERT - Geography

Chapter 2 Inside Our Earth

1. Interior of the Earth  

- Crust – The outermost layer of the Earth, which is the thinnest and made of rocks and minerals.  

- Mantle – The layer beneath the crust, extending up to 2900 km below the surface.  

- Core – The innermost layer of the Earth, made of nickel (Ni) and iron (Fe), also called Nife. It has high temperature and pressure.  

- Lithosphere – The solid outer part of the Earth, including the crust and upper mantle.  

2. Rocks and Their Types  

- Rock – Any natural solid mass of minerals that makes up the Earth's crust.  

- Igneous Rocks – Rocks formed from the cooling and solidification of molten magma.  

- Extrusive Igneous Rocks – Formed when lava cools quickly on the Earth's surface, creating fine-grained rocks (e.g., Basalt).  

- Intrusive Igneous Rocks – Formed when magma cools slowly deep inside the Earth, creating large-grained rocks (e.g., Granite).  

- Sedimentary Rocks – Rocks formed from sediments (small particles of rocks, sand, and minerals) that are compressed and hardened into layers (e.g., Sandstone).  

- Metamorphic Rocks – Rocks that are formed when igneous or sedimentary rocks undergo heat and pressure, changing into a new type of rock (e.g., Limestone → Marble, Clay → Slate).  

- Rock Cycle – The continuous process in which rocks change from one type to another over time.  

3. Fossils and Minerals  

- Fossils – The remains of dead plants and animals trapped in layers of sedimentary rocks.  

- Minerals – Naturally occurring substances with a definite chemical composition and physical properties.  

- Sial – The part of the continental crust made of silica (Si) and alumina (Al).  

- Sima – The part of the oceanic crust made of silica (Si) and magnesium (Ma).  

- Nife – The core of the Earth, made of nickel (Ni) and iron (Fe).  

4. Word Origins (Etymology)  

- Igneous – From the Latin word "Ignis", meaning fire.  

- Sedimentary – From the Latin word "Sedimentum", meaning settle down.  

- Metamorphic – From the Greek word "Metamorphose", meaning change of form.  

~~The END~~

Chapter 2 Inside Our Earth

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