NCERT Solutions for Class 7 Social Science Geography Chapter 2 Inside Our Earth

Primary Rocks:
Any natural mass of mineral matter that makes up the earth’s crust is called a rock. Rocks can be of different colour, size and texture. There are three major types of rocks: igneous rocks, sedimentary rocks and metamorphic rocks. 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.

Igneous Rocks:
When molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in such a way on the crust are called extrusive igneous rocks. They have a very fine grained structure. For example, basalt. The Deccan plateau is made up of basalt rocks. Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are called intrusive igneous rocks.

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. For example, sandstone is made from grains of sand. These rocks may also contain fossils of plants, animals and other microorganisms that once lived on them.

Three layers of the Earth are Crust Mantle Core

Any natural mass of mineral matter that makes up the earth’s crust is called rock. Rocks can be of different colour, size and texture.

There are three types of rocks: Igneous rock or primary rocks Sedimentary rock. Metamorphic rock.

Formation of Extrusive rocks and Intrusive rocks: Extrusive rocks are formed due to rapid cooling and solidification of molten magma on the earth’s surface. Intrusive rocks are formed when molten magma cools down deep inside the earth’s crust.

The change of one type of rock into another type under certain conditions in a cyclic manner is called a rock cycle.

Following are some uses of rocks: They are used as fuels. They are used in industries. They are used in medicines. They are used in fertilizers. They are used in making roads, houses, building, etc.

The types of rocks formed when igneous and sedimentary rocks undergo heat and pressure are called metamorphic rocks.

We cannot go to the centre of the earth because at the centre of the Earth the temperature as well as pressure is extremely high. Not only human being but also rocks and metals get melted at this condition.

Rocks breakdown into small fragments under various conditions. These fragments, called sediments, are transported by wind and water. Layers of sediments are formed when loose sediments are compressed and hardened. These layers of sediments thus form sedimentary rocks.

Ingenious and sedimentary rocks change their form under great pressure and temperature conditions to form metaphoric rocks. The same thing happens with limestone, which under the effect of heat and pressure change into marble, which is an example of metamorphic rock.

Class 7 S.St. Solutions – Geography Chapter 2 Inside Our Earth can be downloaded from this page. Study online and download as PDF options are available on the top of the page. Visit to “NCERT Solutions for Class 7 Social Science Geography Chapter 2” and get your solutions.