NCERT Class 7 Geography Chapter 2: Inside our Earth

Dr. Manishika Jain explains the NCERT Class 7 Geography Chapter 2: Inside our Earth\r
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Onion Peel: Demonstrating Earths Interior\r
Crust\r
Continental - Silica & Aluminum (SIAL) – 35 km\r
Oceanic – Silica & Magnesium (SIMA) – 5 km \r
B/w upper & lower crust – Conrad Discontinuity \r
B/w crust & mantle – Moho Discontinuity \r
Jigsaw puzzle\r
Thinnest Layer\r
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Mantle\r
About 2900 km thick\r
85% by volume\r
64% by mass\r
Made of iron but mainly silicates\r
Asthenosphere – Upper mantle – Convection currents \r
Viscous, weak and ductile\r
Just below lithosphere\r
Main source of Magma\r
B/w Upper & lower mantle – Repetti Discontinuity\r
B/w Mantle & Core – Guttenberg Discontinuity\r
Core\r
Radius of about 3500 km\r
Made of Iron & Nickel (NIFE)\r
High temperature & pressure \r
15% of earths volume\r
32.5% of earths mass\r
B/w Outer & Inner Core – Lehmann Discontinuity \r
Outer Core – Liquid (Slow Moving – Produces Earths Magnetic Field)\r
Pressure, Density increases towards center\r
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Rocks\r
Earths Crust\r
Natural mass of matter that makes the crust\r
Differ in Size, Color & Texture\r
3 Types of Rocks\r
Igneous\r
Sedimentary\r
Metamorphic\r
Igneous Rocks\r
Molten Magma Cools & Solidifies\r
Also known as Primary Rocks\r
Two Types\r
Intrusive – Cools inside, Slowly cools, Forms Large grains - Granite\r
Extrusive – Comes on Surface – Basalt (Deccan Plateau) – Fine Grained\r
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Sedimentary Rocks\r
Rocks roll, crack & hit to break\r
Sediments are transported\r
Then compressed & hardened\r
Sandstone – made from sand\r
Red Fort – red sandstone\r
Include fossils\r
Metamorphic Rocks\r
Igneous & Metamorphic change under heat & pressure\r
Clay → Slate\r
Limestone → Marble\r
Taj Mahal – White Marble\r
Rock Cycle – Transformation\r
Minerals\r
Naturally occurring substances \r
Have certain physical properties \r
Definite chemical composition\r
Fuels – Coal, Petroleum & Natural Gas\r
Industries – Iron, Aluminum\r
Medicines – Calcium, Phosphorus, Magnesium\r
For NCERT Based questions refer - \r
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For IAS Refer -