7 Geography Chapter 2 Inside Our Earth

Chapter Notes and Summary
• earth is constantly undergoing changes inside and outside.
• earth is made up of three concentric layers-crust, mantle and core.
• Crust is uppermost thinnest layer, made up of silica and alumina and thus called sial.
Mantle is just beneath crust.
• Innermost layer is core, which is made up of nickel and iron and thus called nife (ni-nickel and fe-ferrous i.e. iron).
• Crust is made up of various types of rocks.
• Rocks are of three types : igneous, sedimentary and metamorphic.
• Igneous rocks, also known as primary rocks, are formed by solidification of lava, and are of two types—intrusive rocks and extrusive rocks.
• Sedimentary rocks are formed by transportation and deposition of sediments.
• Metamorphic rocks form from igneous and sedimentary rocks, under heat and pressure.
• process of transformation of rocks from one form to another is called rock cycle.

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