The inner core, the outer core, mantle and crust are the four layers of earth

The Inner Core

It is the centre and the hottest layer of the Earth. The inner core is solid and made up of iron and nickel with temperature up to 5,500^oC. Due to its immense <a href="https://byjus.com/physics/heat-energy/" rel="noopener" target="_blank">heat energy</a>, the inner core is more like the engine room of the Earth.

The Outer Core

The outer core of the Earth is similar to a very hot ball of metals, whose temperature is around 4000 ^oF to 9000⁰F. It is so hot that the metals inside are all in the liquid state. The outer core is located around 1800 miles under the crust and approximately 1400 miles thick. It is composed of metals such as iron and nickel. The outer core surrounds the inner core.

The inner core has pressures and temperatures so high that the metals are squeezed together and not able to move like a liquid, but are forced to vibrate instead of solid.

Mantle

Mantle is the widest section of the Earth. Its thickness is approximately 2,900 km. The mantle is mainly made up of semi-molten rock known as magma. The rock is hard in the upper part of the mantle, but lower down the rock is softer and begins to melt.

The mantle is located directly under the Sima. The mantle consists of very hot and dense rock. This layer of rock flows like asphalt under heavy weight. This flow is because of the greatest temperature differences from the bottom to the top of the mantle. The reason behind the plates of the Earth move is the movement of the mantle. Its temperature varies between 1600 oF at the upper part to 4000 oF near the bottom.

Crust

The crust is the outer layer where we live. The thickness is around 0-60 km. It’s a solid rock layer divided into two types:

1. Continental crust covers the land and,
2. Oceanic crust covers water

The crust is the most widely studied and understood. Mantle is hotter and capable of flowing. The outer and inner core are much hotter with great pressures that you can be squeezed into a ball smaller than a marble if you are able to go in the center of the Earth.

• The Port of Kolkata is a riverine port in the city of Kolkata, India, located around 203 kilometres (126 mi) from the sea. It is the oldest operating port in India, and was constructed by the British East India Company.
•  Kolkata is an Inland riverine port serving a large hinterland of Ganga Brahmaputra basin.
•  It is located along the banks of the Ganges.

Throughout different places, the Brahmaputra is known by different names: the Yarlung Tsangpo is Tibet, the Dihang or Siang in Arunachal Pradesh, and the Jamuna in Bangladesh.

Nanda Devi and Dhaulagiri are mountain peaks in the Himalaya mountain range.

पार्थिव ग्रह पृथ्वी की भाँति ही शैलों और धातुओं से बने हैं और अपेक्षाकृत अधिक घनत्व वाले हैं। जनक तारे के बहुत नजदीक होने के कारण और अत्यधिक तापमान के कारण इन ग्रहों की गैसें संघनित नहीं हो पाईं और घनीभूत भी न हो सकी। छोटे होने के कारण इनकी गुरुत्वाकर्षण शक्ति भी कम रही, जिसके। फलस्वरूप इनसे निकली हुई गैसें इन पर रुक नहीं सकीं। पहले चार ग्रह बुध, शुक्र, पृथ्वी और मंगल पार्थिव ग्रह कहे जाते हैं।

1. Parent Material: It is deposited by streams or derived from in-situ weathering. In this stage, soil inherits many properties like mineral composition, color, particle size, and chemical elements. For example- Black soil-derives its colour from lava rock

2. Climate: It is one of the important factors in the formation of soil because it affects the rate of weathering of the parent rock.

3. Parent Material: It is deposited by streams or derived from in-situ weathering. In this stage, soil inherits many properties like mineral composition, color, particle size, and chemical elements. For example- Black soil-derives its colour from lava rock

4 Climate: It is one of the important factors in the formation of soil because it affects the rate of weathering of the parent rock.

Answer: troposphere

The troposphere is the lower most layer of the atmosphere. This layer contains dust particles and water vapour. All types of changes in climate and weather take place in this layer. This is the most important layer for all biological activity.

Answer: troposphere

The troposphere is the lower most layer of the atmosphere. This layer contains dust particles and water vapour. All types of changes in climate and weather take place in this layer. This is the most important layer for all biological activity.

The flow of water through well-defined channels is known as ‘drainage’ and the network of such channels is called a ‘drainage system’. The drainage pattern of an area is the outcome of the geological time period, nature and structure of rocks, topography, slope, amount of water flowing and the periodicity of the flow.

Ocean currents are streams of water flowing on ocean surface in different directions. These currents can be warm or cold carrying the currents which can either be cold or warm from one region of Earth's surface to another. Warm current flows from Equator to poles whereas cold currents originate in the polar region and flow towards the Equator. 

Warm currents move from the equator to the poles ex Gulf Stream, South Atlantic Current and Cold currents move from poles to the equator ex Labrador Current, West Australian Current. 

Physical geography includes study of Lithosphere, Atmosphere, Hydrosphere & Biosphere- each element is very important for human beings.
Landforms provide base for agriculture, industries, transport and communication, and settlements. Mountains provide water to rivers, forests-center for tourist spots.
Climate influences on the cropping pattern, livestock, food and clothes of the people.
limate and precipitation influence the type of forests. Oceans provide food, water transport, and influence the climate; they are the source of hydrological cycle. (i) Geomorphology is devoted to the study of land forms, their evolution and related processes.
(ii) Climatology encompasses the study of structure of atmosphere and elements of weather and climates and climatic types and regions.
(iii) Hydrology studies the realm of water over the surface of the earth including oceans, lakes, rivers and other water bodies and its effect on different life forms including human life and their activities.
(iv) Soil Geography is devoted to study the processes of soil formation, soil types, their fertility status, distribution and use

The three types of earthquake waves are described below:

• ‘P’ or longitudinal waves or primary waves -  These waves travel in the direction of their movement. They can travel through solid as well as liquid matter.
• ‘S’ or transverse or secondary waves -These waves travel at right angle to the direction of their oscillation. They can travel in solid media only.
• ‘L’ or Long Waves -  These are surface waves. These do not go deep into the earth.

Geographers are important for any country because:

• They study the variations and association of the features on the earth surface e.g. cropping pattern differs from place to place and it is due to difference in the climate, soil, demand, transport facility and capacity of the farmer.
• A geographer also studies the cause and effect relationships.
• The interaction between man and nature is highly dynamic and not static; so it is also called as the study of the relation between unstable earth and untrusting man.
• He helps to predict climate.
• He helps in handling natural calamities.

A place is classed as a subcontinent when it is part of a continent but is considered either geographically or politically as an independent entity or it is smaller than a continent. 

India is often called a subcontinent because it is a distinct landmass, not just a country. While it has many features of a continent, it is not as big as one, so is not considered a continent. 

India was once a continent (or at least a very large island). Due to continental drift, India moved north and became part of Asia. 

India is now joined with the continent of Asia, but is a distinct area separated by the Himalayas. Originally it was a separate geologic plate, but has collided and merged with Asia. 

Politically, the Indian subcontinent includes Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka. Sometimes, the geographical term 'Indian subcontinent' is used interchangeably with 'South Asia', although that last term is used typically as a political term and is also used to include Afghanistan.

Body waves are earthquake waves which are generated due to the release of energy at the focus. They radiate and move in all directions from the point of hypocentre or the ‘focus’ and travel through the body of the earth. Hence the name body waves.

There are two types of body waves. They are called P and S-waves

Earth's atmosphere is composed of about 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases. Trace amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent.

Earthquakes are commonly found in thin narrow belts associated with a plate boundary. Most volcanoes are distributed along the plate boundary. An example of a highly active earthquake zone is the west coast of North America and South America Occasionally, volcanoes are found in the middle of plates (e.g. Hawaii).

The temperature of air at every place is influenced by :

• The latitude of the place
• The altitude of the place
• Distance from the sea
• The air- mass circulation
• The presence of warm and cold ocean currents
• Local aspects

(1 ERATOSTHENES)
The earth consists of physical and cultural features. They are different from one place to another. This difference helped to understand the relation between physical and cultural features. Physical features provided the stage and human societies enacted the drama to develop their skills. With the use of skills and tools, he modified the nature

“GEOGRAPHY IS THE DESCRIPTION OF THE EARTH.”

Who was the first to coin the term ‘Geography’?
ERATOSTHENES, A GREEK SCHOLAR (276-194 BC)in the third century. His famous book was called ‘Geographia.’

What is the origin of the word ‘Geography’?
The word ‘geography ‘ is derived from two Greek words geo= earth, graphos=description.
Some scholars defined geography as the description of the earth as the abode of human beings.

How can we say that the earth is ‘multidimensional’?
Many Sciences developed to describe the physical features of the earth such as Geology, Pedology, Oceanography Botany Zoology and Meteorology & Cultural features of the earth such as Economics, History, Sociology Political Science, Anthropology,

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<a href="https://mycbseguide.com/blog/geography-discipline-class-11-notes-geography/" ping="/url?sa=t&source=web&rct=j&url=https://mycbseguide.com/blog/geography-discipline-class-11-notes-geography/&ved=2ahUKEwjKwsyI0oHtAhVRbn0KHfXhA5QQFjACegQIBBAC" rel="noopener" target="_blank">Geography as a Discipline class 11 Notes Geography ...</a>