Inside our earth (grade VII, c-2)

A complete slide on the "Inside Our Earth". Helping for the school and higher school students.

1. Chapter 2 Class:-7 Geography INSIDE OUR EARTH

2. 2 .INTERIOR OF THE EARTH :- The earth is a dynamic planet. It is constantly undergoing changes inside and outside. 1.EARTH :- a). Layers of the Earth Crust - outermost layer (35km) Mantle – middle layer (2900 km) Core – innermost layer( 3500km radius)

3. A).LAYERS OF THE EARTH :- a1). CRUST :- The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the layers. It is about 35 km on the continental masses and only 5 km on the ocean floors. The main mineral constituents of the continental mass are silica and alumina . It is thus called sial . The oceanic crust mainly consists of silica and magnesium ; it is therefore called sima

4. A).LAYERS OF THE EARTH :- a2). MANTLE - Just beneath the crust is the mantle which extends up to a depth of 2900 km below the crust. Silicates and magnesium oxide are generally found in mantle Mantle is in molten state. a3). CORE - The innermost layer is the core with a radius of about 3500 km. It is mainly made up of nicke l and iron and is called nife ( ni –nickel and fe –ferrous i.e. iron). The central core has very high temperature and pressure. The core is divide into part; outer core and inner core . Outer core is liquid and inner core is solid .

5. A).ROCKS AND MINERALS :- The earth’s crust is made up of various types of rocks 1.MINERALS - Minerals are solid substances that are present in nature and can be made of one element or more elements combined together. E.g Gold , Silver, carbon, Sodium coal, natural gas and petroleum etc. 2. ROCKS - Any natural mass of mineral matter that makes up the earth’s crust is called a rock. It is a naturally formed, non-living earth material.

6. A).FORMATION OF ROCK :- When the molten magma cools, it becomes solid. Rocks thus formed are called igneous rocks . They are also called primary rocks. There are two types of igneous rocks: intrusive rocks and extrusive rocks .

7. A).TYPES OF ROCK :- ROCK Igneous rock Metamorphic Rock Sedimentary Rock Primary Rock Intrusive rocks Inside the earth Surface Extrusive rocks On the earth Surface

8. A).IGNEOUS ROCKS - When the molten magma cools, it becomes solid. Rocks thus formed are called igneous rocks. They are also called primary rocks.

9. Some Example:

10. B ).SEDIMENTARY ROCKS; - Rocks roll down, crack, and hit each other and are broken down into small fragments. These smaller particles are called sediments . These sediments are transported and deposited by wind, water, etc. These loose sediments are compressed and hardened to form layers of rocks. These types of rocks are called sedimentary rocks . e.g sandstone is made from grains of sand. Sediments

11. B ).MEATAMORPHIC ROCKS; - Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure . E.g 1. Clay changes into slate 2. limestone into marble

12. C).ROCK CYCLE: - One type of rock changes to another type under certain conditions in a cyclic manner. This process of transformation of the rock from one to another is known as the rock cycle. W hen the molten magma cools; it solidifies to become igneous rock. These igneous rocks are broken down into small particles that are transported and deposited to form sedimentary rocks . When the igneous and sedimentary rocks are subjected to heat and pressure they change into metamorphic rocks. The metamorphic rocks which are still under great heat and pressure melt down to form molten magma

13. C).ROCK CYCLE: -

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