Cl-7 Geo ch-2 Inside our earth notes ppt

​Layers of earth - CRUST

Crust :-

The uppermost layer on the earth 's surface is crust

• extends up to 35 kms (continental mass) , thinnest layer

• extends up to 5 km (ocean floors)

• continental mass - sial (silica and alumina)

• oceanic crust - sima (silica and magnesium)

​Layers of earth - MANTLE

& CORE

Mantle :- Layer beneath the crust

• extends up to a depth of 2900 km

  Core :- Innermost layer with high temp. and pressure

• radius - 3500km

• made up of nife(nickel and iron {ferrous i.e. iron})

Minerals are naturally occurring substances which have certain physical and chemical composition - used as fuels eg. coal , natural gas etc.

Minerals

Any natural mass of mineral matter that makes up the earth 's crust is called a rock..

Rocks

Igneous rocks

When molten magma comes out of volcano and cools it forms igneous \ primary rocks. The rocks formed with magma out of volcano are extrusive igneous rocks(basalt). The molten magma offers great heat and pressure in the volcano before bursting. It sometimes causes several cracks. When these cracks fill with magma and cool , they form intrusive igneous rocks(granite)

Now igneous rocks fall down and break into sediments. These sediments are transported by air and water mediums. These are then deposited on the soils. After many years and a lot of layers of sediments , compressed and hardened results in sedimentary rocks. They may also contain fossils(the remains of organisms). Eg sandstone

​Metamorphic Rock

When sedimentary rock is subjected to heat and pressure it changes its form into metamorphic rock. Eg. Clay to slate and limestone to marble.

playing seven stones(pithoo),stapu , gitti , constructions etc.. Redfort is made of red sandstone. Taj Mahal - white marble

use of rocks

When metamorphic rocks again changes its form , it becomes lava which again on solidifying gives igneous rocks

Completing rock cycle