The Earth is a unique planet. Inside Our Earth is made up of three layers- crust, mantle & core. In this post, we’ll take a closer look at the layers that make up the Earth’s interior and the processes that shape our planet from the inside out. Students will get to know about the interior of the Earth in detail, which will help them score good marks on the exam. Class 7 Geography Chapter 2 notes will help them to learn how the rocks are formed. Ncert Class 7 Geography Chapter 2 notes will assist students in preparing an internal assessment for their Social Science exam.
Inside Our Earth Class 7 Notes
What are the layers of the Earth?
The Earth has been undergoing continuous transformation, both internally and externally. So it is known as a dynamic planet. The interior part of our Earth is divided into three layers – Crust, Mantle, and Core.
What is the Crust of the Earth?
- It is the uppermost layer of the Earth’s surface.
- It is the thinnest layer.
- It is composed of rocks and minerals.
- Its surface is covered with soil and minerals.
- The crust is divided into two layers upper continental crust and the Lower Oceanic Crust.
What are the 2 types of Earth’s crust?
- The continental crust is 35 km.
- Silica and alumina are the main minerals of the continental crust inside the earth.
- It is called SIAL- Si-Silica and al-alumina.
- The ocean crust is 5 km.
- Silica and magnesium are the main minerals of the oceanic crust inside the earth.
- It is called SIMA-Si-silica and Ma-magnesium.
What is the Mantle of the Earth?
- It is under the crust and the second layer.
- It extends up to a depth of 2900 km. under the crust.
- It is located between the mantle and core.
- Its thickness is about 2900 km.
- It contains molten magma.
- It is composed of olivine, a combination of iron, magnesium, and silicon.
- It consists of two layers-the upper mantle and the lower mantle.
What is the Core of the Earth?
- The core is the innermost layer.
- It extends about 3500 km.
- It is made up of nickel and iron and is called life ( ni-nickel and fe-ferrous i.e. iron.
- It has a very high temperature and pressure.
- It consists of two layers outer core and the inner core.
What is Rock and Minerals Class 7?
The Earth’s crust is made up of different types of rocks. A rock is a natural substance composed of solid crystals of different minerals that form the earth’s crust. Rocks are of different types of sizes, colors, and textures. The study of rocks is called petrology.
What are the 3 types of rocks?
What are Igneous Rocks?
These are formed by the cooling and solidification of molten magma under the earth’s crust.
These are called Primary rocks as all other rocks are formed from these.
Igneous rocks are of two types:-
- Intrusive Rocks:
These are formed when the molten magma solidifies inside our Earth. These form large crystals.
Ex. granite and dolerite.
- Extrusive Rocks:
These are formed when the molten magma comes out on the Earth’s surface as lava and cools quickly. These form small crystals.
Ex. basalt and pumice
What are Sedimentary Rocks?
These are formed by the deposition of small fragments on the Earth’s surface. These are carried by the agents of nature as rain. wind, ice plants, and animals.
Sedimentary rocks are of three types:-
- Mechanically: These are formed by the physical accumulation and compaction of minerals.
Ex. sandstone, shale, and mudstone.
- Organically: These are formed from the remains of organisms.
Ex. coal and limestone.
- Chemically: These are formed by chemical processes.
Ex. gypsum and rock salt.
What are Metamorphic Rocks?
These rocks are formed when igneous and sedimentary rocks are completely changed due to excessive heat and pressure inside our Earth. These processes may take millions of years.
Ex. clay into slate, Limestone into marble, Sandstone into quartzite, Coal into granite.
What are the uses of rocks and minerals Class 7?
- Rocks are used in building materials. Ex. granite, marble, sandstone, and basalt.
- Rocks are used for making roads and houses.
- Many machines and tools are made of metals.
- Many useful things such as a pen, computers, cars, and cooking pots are made of minerals
- Minerals such as coal, petroleum, and natural gas are essential power sources.
- Chemicals found in rocks are used to make fertilizers.
What is the rock cycle?
A process in which rocks are continuously transformed from one type of rock to another through erosion, deposition, heat, pressure, melting, and cooling is called the rock cycle.
Class 7 Geography Chapter 2 Extra Questions and Answers
1. What are the three layers of the Earth?
ANSWER: Crust, mantle, and core.
2. Which is the uppermost and thinnest layer of the earth?
3. Name the main mineral constituents of the continental mass.
ANSWER: Silica and alumina.
4. Name the main mineral constituents of the oceanic mass.
ANSWER: Silica and magnesium
5. Where is the deepest mine in the world?
ANSWER: South Africa.
6. What is the radius of the earth?
ANSWER: 6371 km.
7. Which is the innermost layer of the earth?
ANSWER: The core, is made up of nickel and iron.
8. What is the earth’s crust made up of?
ANSWER: The Earth’s crust is made up of various types of rocks.
9. Name the three types of rocks.
ANSWER: Igneous rocks, sedimentary rocks, and metamorphic rocks.
10. What is lava?
ANSWER: Lava is red molten magma coming out from the interior of the earth on its surface.
11. What is a fossil?
ANSWER: The remains of dead plants and animals are trapped in the layers of rocks.
12. Give an example of an intrusive rock.
13. Give an example of metamorphic rock.
14. What is rock?
ANSWER: A piece of earth is made up of two or more minerals.
15. What is geology?
ANSWER: The science that deals with the structure of the earth is called geology.
16. Who are called geologists?
ANSWER: The people who study the structure of the earth are called geologists.
17. What is petrology?
ANSWER: The study of rocks.
18. How many years ago was the Earth formed?
ANSWER: 4.54 billion years ago.
19. What is the average density of the Earth?
ANSWER: The average density of the Earth is about 5.5 g per cubic cm.
20. What is mineralogy?
ANSWER: The study of minerals.
class 7 pdf
For Class 7 Notes Geography Chapter 2, you may click on the link below and get a PDF file.
Inside Our Earth Class 7 Pdf
1. What are the three layers of the earth’s interior, and what are their characteristics?
The three main layers of the Earth’s interior are the crust, mantle, and core. Their characteristics are:
Crust: The Earth’s crust is the outermost layer and is composed of solid rock.
Mantle: The mantle is the layer that lies between the crust and the core. It is composed of solid rock that is under extreme pressure and high temperature.
Core: The core is the innermost layer of the Earth, and it is composed mainly of iron and nickel.
2. What are minerals, and how are they formed?
Minerals are naturally occurring, inorganic substances that have a defined chemical composition and crystal structure.
Minerals can be formed in a variety of ways, including Crystallization from magma, Precipitation from solution, Weathering, and erosion.
3. What is the rock cycle?
The rock cycle is the natural process by which rocks are transformed from one type to another over time. It involves a series of geological processes, including erosion, weathering, melting, cooling, and solidification.
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