(i) Due to the current inflow of fresh water, the Caspian sea is a freshwater lake in its northern portions and is most saline on the Iranian shore where the catchment basin contributes little flow.
(ii) Currently, the mean salinity of the Caspian is one third that of Earth's Oceans.

(i) Salt in the ocean comes from rocks on land.
(ii) The rain that falls on the land contains some dissolved carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic due to carbonic acid (which forms from carbon dioxide and water).
(iii) As the rain erodes the rock, acids in the rainwater break down the rock. This process creates ions, or electrically charged atomic particles. These ions are carried away in run off to streams and rivers and ultimately to the ocean.
(iv) Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not used up and are left for long periods of time where their concentrations increase over time.
(v) Two of the most prevalent ions in seawater are chloride and sodium. Together, they make up over 90 percent of all dissolved ions in the ocean. Sodium and Chloride are 'salty'. So, the oceans are salty

(i) The biotic and abiotic resources found in the oceanic water and at the bottoms are called manne resources.
(ii) Fishes, plankton, sea grass, coral, etc are biological resources.
(iii) Petioleum, Natural gas, Metallic Minerals, Sand, gravet, etc, are mineral resources.
(iv) Energy fuels, Tidal energy, wave energy, etc, are energy resources.
Influence:
(i) The ocean's resources play a vital role in sustaining the needs of society.
(ii) A diverse array of marine organisms is used for food, medicine, cosmetics, and a wealth of industrial applications.
(iii) The world's demand for energy, minerals and water have become increasingly dependent on non-living marine resources.

(A) Continental Shelf
(i) A shallow and gently sloping platform extending out from the adjoining continental land mass into the sea is called Continental Shelf.
(ii) It is almost a uniform zone of sea bed with a gentle gradient.
(iii) It is significant in promoting richest fishing grounds.
(iv) Since the continental shelf in shallower, thus enables sunlight to penetrate through the water. This encourages abundant growth of grass, sea weeds and plankton to feed fishes.
(v) The continental shelves have extensive deposits of minerals and mineral fuels.
(vi) Hence, this zone becomes accessible for oil drilling and mining activities.
(B) Continental Slope
(i) A steep slope which descends from the edge of the continental shelf to the deep ocean-bed is called continental slope.
(ii) It forms a boundary between the Continental Crust and the oceanic crust.
(iii) This zone is free from deposits as they are steep.
(iv) The most important characteristic of continental slope is the presence of deep canyons and trenches.
(v) Due to the low penetration of sunlight, the slope has nearly freezing temperature.
(vi) Hence aquatic life has very slow rate of metabolism.

(i) The territorial expansion of the Chola empire began under Rajaraja I.
(ii) The Pallava kingdom had already been assimilated into the Chola kingdom
(iii) Pandya kingdom remained independent, but was subservient to the Cholas.
(iv) The empire expanded further under Rajendra I. who had successfully taken his armies as far to the north east as the river Ganga.
(v) He had also sent naval expeditions against the Sailendra kingdom of Sri Vijaya (in Indonesia), Kadaram (Kedah) and Ceylon.
(vi) This earned him the title "Gangaiyum Kadaramum Konda Cholan".
(vii) Ceylon remained a province of Chola for 10 years.
(viii) The marriage alliance with the eastern Chalukyas under Rajendra's grandson Kulottunga helped to extend his expire up to the border of Orissa.
(ix) Trade with south-east Asia and China expanded greatly during the Chola period.
(x) The continued interaction with Tamil merchants resulted in the spread of the Indian culture and art into south-east Asia, as seen in the magnificent temples of Angkorwat in Combodia.

(i) The Mughal empire was founded by Babur in 1526 A.D. (C.E.) after he defeated Ibrahim Lodi at Panipat.
(ii) The first six Mughal Emperors are referred to as the 'Great Mughals'.
(iii) Aurangzeb was the last of the great Mughals.
(iv) Akbar consolidated the Mughal Empire through conquest and through a policy of conciliation with the Religious based kingdoms of Rajasthan.
(v) Though the Mughal empire began to disintegrate after Aurangzeb, it continued to exist nominally till 1857 A.D. (C.E.) when the British finally ended the virtually non-existent empire.
(vi) A new power centre rose in Maharashtra in the seventeenth century, and the Marathas under the leadership of Shivaji seriously undermined the authority of the Mughals in western India.
(vii) At its height, the empire stretched over most of the Indian sub-continent.
(viii) Only the south-western region of Kerala and southern Tamilnadu were not directly under Mughal rule.

(i) Out of the fight between two Daimyo chief families, the Tara and the Minamota, Yoritomo emerged successful.
(ii) The emperor gave him the high sounding title of Sei-i-tai-Shogun.
(iii) This title meant Barbarian-subduing-Great-General.
(iv) The title carried full power to govern hereditarily.
(v) The Shogun became the real ruler. In this way began the rule of Shogunate.
(vi) Yoritomo established his military capital at Kamakura .
(vii) Therefore, the first Shogunate is called the Kamakura Shogunate.
(viii) Samurai or warriors formed the feudal military government.
(ix) The Ashikaga Shogunate replaced them and ruled for nearly 235 years. But this was a period of conflict and war.
(x) Three men Borbunaga, a Daimyo or noble, Hideyoshi, a peasant and Tokugawa Iyeyasu, one of the distinguished nobles ultimately rescued Japan from civil war.
(xi) By the end of 16th century, the whole of Japan was again united.

RISE OF ATHENIAN'S:
(i) In Athens the pressure from below resulted in the replacement of both oligarchy and tyranny by "democracy".
(ii) The law-making power in Athens was vested in an assembly open to all freemen.
(iii) The Persian expedition danger had united the Greeks.
(iv) The Athen's democracy survived for about 200 years.
GROWTH:
(i) Athens had a great leader Pericles.
(ii) He held power for thirty years.
(iii) During his rule, Athens became a noble city with magnificent buildings.
(iv) There were great artists and great thinkers.
(v) Historians therefore call this the age of Pericles.
(vi) Greeks famous historian Socrates and his successor Thucydides, lived about this time.
(vii) The thinkers of the Pericles era sought to find a new objective basis for arriving at truth.
(viii) The greatest of them was Socrates. As a philosopher he discussed difficult problems with his friends so that truth might emerge out of the discussions.
(x) Plato was his illustrious disciple, He argued that truth must depend on a realm out side human experience accessible only to philosophic elite.
(xi) Aristotle studying under Plato, laid stress on the empirical knowledge of the existing physical and social world.
(xii) Democritus and Epicurus developed a materialist view of the world.

1. Craft production and craft specialization were important aspects of urbanization.
2. In the Sangam Age there were professional groups that produced various commodities.
3. The system of production of commodities is called industry.
4. Pottery was practised in many settlements. People used pottery produced by kalam ceyks in their daily activities and so they were made in large numbers.
5. Black ware, russet-coated painted ware, black and red ware potteries were the different types of pottery used.
6. Iron manufacturing was an important artisanal activity. Iron smelting was undertaken in traditional furnaces.
7. Furnaces and raw ore have been found in many archaeological sites.
8. Sangam Age literature mentioned about the Iron manufacturing.
9. They produced Iron implements required for agriculture and warfare (sword, daggers and spears).

The structure of employment denotes the number of workers engaged in different sectors of the economy.
Primary Sector: Agriculture, forestry, animal husbandry, poultry, dairy farming, fishing, etc.
Secondary Section: Manufacturing, small and large scale industries and constructional activities.
Tertiary Sector: Transport insurance banking, trade, communication, real estate, government and non-government services.
In developing countries like India that a large work force will be engaged in Primary Sector, while a small proportion in Secondary and Tertiary sectors.

USE OF NON-CONVENTIONAL SOURCES OF ENERGY:
(i) India depends on thermal and hydro power plants to meet its power needs.
(ii) Both these sources have an adverse environmental impact.
(iii) They emit large quantities of carbon dioxide, which pollute the environment.
SOLAR POWER:
(i) Solar power is the conversion of energy from sunlight into electricity either directly using photovoltaic cells or indirectly using concentrated solar power.
(ii) Solar panels absorb the sunlight as a source of energy to generate electricity.
(iii) A solar electric system can reliably produce electricity for our home and offices.
(iv) It reduces their electricity costs.
(v) Tamilnadu is the state with highest installed solar capacity in India.
(vi) Tamilnadu is one of the leading solar power producing states in India.

(i) Pressure groups are the interest groups that work to secure certain interest by influencing the public policy
(ii) They are non-aligned with any other party.
(iii) They work as an indirect yet powerful group to influence the policy decisions.
(iv) They support through activities such as petitions, marches, demonstrations and other forms of political protest.
(v) It comments on government policy and using high profile academics, scientists and even celebrities to get their views across with an emphasis to cultivate expert authority.
(vi) Many pressure groups are vital sources of information and render advice to the government.
(vii) They are regularly consulted in the process of policy formulation.

Merits:
(i) As the voters elect their representatives directly, direct elections are considered to be a more democratic method of election.
(ii) It educates people regarding the government activities and helps in choosing the appropriate candidates. Also, it encourages people to play an active role in politics.
(iii) It empowers people and makes the rulers accountable for their actions.
Demerits:
(i) Direct elections are very expensive.
(ii) Illiterate voters sometimes get misguided by false propaganda and sometimes campaigning based on caste, religious and various other sectarian consideration spose serious challenges.
(iii) Since conducting direct elections is a massive exercise, ensuring free and fair elections at every polling station is a major challenge to the Election Commission.
(iv) There are instances of some political candidates influencing the voters through payments in the form of cash, goods or services.
(v) Election campaigns sometimes results in violence, tension, law and order problems and affects the day-to-day life of people.

Precipitation
Falling down of condensed water vapour in different forms is called Precipitation. When the dew point is reached in the cloud water droplets become saturated and start to fall. Hence, they fall on the earth as precipitation.
The climatic conditions/ factors influencing the forms of precipitation mainly are:
• Temperature.
• Altitude.
• Cloud type.
• Atmospheric conditions.
• Precipitation process.
The main forms of precipitation include drizzle, rain, sleet, snow, hail, etc.
Drizzle: Falling of numerous uniform minute droplets of water with diameter of less than 0.5 is called a drizzle.mm from low clouds. Sometimes drizzles are combined with fog and hence reduce visibility.
Rain: Rain is the most widespread and important form of precipitation in places having temperature above the freezing point. It occurs only when there is abundant moisture in the air. The diameter of a rain drop is more than 5 mm.
Sleet: Sleet refers to a precipitation, in the form of pellets made up of transparent and translucent ice. This precipitation is a mixture of snow and ram.
Snow: Snow is formed when condensation occurs below freezing point. It is the precipitation of opaque and semi opaque ice crystals. When these ice crystals collide and stick together, it becomes snowflakes.
Hails: Hails are chunks of ice (greater than 2 em in diameter) falling from the sky, during a rainstorm or thunderstorm. Hailstones are a form of solid precipitation where small pieces of ice fall downwards. These are destructive and dreaded forms of solid precipitation because they destroy agricultural crops and human lives.

According to their height, clouds are classified into the following types
(i) High clouds (6 - 20 km Height)
(ii) Middle clouds (2.5 km - 6 km Height)
(iii) Low clouds (ground surface to 25 km height)
These major types of clouds are further divided into different types on the basis of shape and structure.
High clouds
Cirrus: Detached clouds in the form of white delicate fibrous silky filaments formed at the high sky (8000 meters to 12000 meters) are called Cirrus clouds. These clouds are dry and do not give rainfall.
Cirro-cumulus: White patched, sheet or layer like clouds composed of ice crystals.
Cirro-stratus: Smooth milky transparent whitish clouds composed of tiny ice crystals,
Middle clouds
Alto-stratus: Thin sheets of grey or blue coloured clouds in uniform appearance, consisting of frozen water droplets.
Alto-cumulus: clouds fitted closely together in parallel bands, called as 'Sheep clouds' or wool pack clouds.
Nimbo stratus: These are clouds of dark colour very close to the ground surface associated with rain, snow or sleet.
Low clouds
Strato-cumulus: Grey or whitish layer of non-fibrous low clouds found in rounded patches at a height of 2500 to 3000 metres, associated with fair or clear weather.
Stratus: Dense, low lying fog-like clouds associated with rain or snow.
Cumulus: Dome-shaped with a flat base often resembling a cauliflower, associated with fair weather.
Cumulo-nimbus: Fluffy thick towering thunderstorm cloud capable of producing heavy rain, snow, hailstorm or tornadoes.

Atmosphere:
The blanket of air that surrounds the Earth is called the atmosphere. The five atmospheric layers are Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.
Troposphere: The lowest layer of the atmosphere is the troposphere. The Greek word 'tropos' means 'turn' or change. The layer extends up to 8 kms at the poles and up to 18 kms at the Equator. The temperature decreases with increasing height. Almost all weather phenomenon take place in this layer. Hence it is called weather making layer. The upper limit of the troposphere is called as tropopause.
Stratosphere: Stratosphere lies above the troposphere. It extends to a height of about 50 km above earth surface. Since this layer is a concentration of ozone molecules, it is also referred as ozonosphere.The temperature increases with increase in height in this layer, Large jet planes normally fly here. The upper limit of the stratosphere is called as stratopause.
Mesosphere: Mesosphere extends between 50km and 80km. The temperature increases with increasing height. Radio waves transmitted from earth are reflected back to earth from this layer: Most of the meteors nearing the earth, get burned here. The upper most limit of the mesosphere is the mesopause.
Thermosphere: Thermosphere exists above the mesosphere. It extends to about 600 km. The composition of gases in the lower thermosphere is more or less uniform, hence it is called "Homosphere". The upper portion of the thermosphere has uneven composition of gases and hence it is referred as "Heterosphere". Here the temperature increases with increasing height.Ionosphere is a layer of the thermosphere that contains Ions. and free electrons.
Exosphere: The uppermost layer of the atmosphere is called exosphere. This layer is extremely rarefied with gases and gradually merges with the outer space. This zone is characterized by aurora Australis and aurora borealis

(i) Empowerment of the poor and illiterates to enjoy the goodness of democracy.
(ii) Willingness among the elected people not to misuse their powerful position and public wealth.
(iii) Eradication of social evils and dangers from which democracy suffers.
(iv) An impartial and efficient press to form public opinion.
(v) Presence of strong public opinion.
(vi) Feeling of tolerance and communal harmony among the people.
(vii) Awareness among the people of the fundamental rights that they are entitled to enjoy.
(viii) Conscious check and vigilance on the working of the elected representatives.
(ix) Powerful and responsible opposition

Philosophy:
1. Lao Tze was the master achive keeper of Chou state. He was the founder of Taoism.
2. He argued that desire is the root cause of all evils.
Confucius:
1. Confucius was famous among the Chinese philosophers and a political reformer.
2. He insisted on cultivation of one's own personal life.
3. He said, "If personal life is cultivated, family life is regulated and once family life is regulated, national life is regulated."
Mencius:
1. Mencius was another well-known Chinese philosopher.
2. He travelled throughout China and offered his counsel to the rulers.
Literature:
1. Chinese poets and philosophers contributed to the development of Chinese civilisation.
2. Sun-Tzu, B military strategist, wrote the work called Art of War.
3. The Spring and Autumn Annals is the official chronicle of the state at the time.
4. The Yellow Emperor's Canon of Medicine is considered China's earliest written book on medicine.
5. It was codified during the time of Han Dynasty.

Deposition occurs when the speed of wind is reduced by the presence of obstacles like bushes, forests and rock structures. The sediments carried by wind get deposited on both the wind ward and leeward sides of these obstacles Some of the depositional landforms are sand dunes, barchans and loess.
Sand Dune: In deserts, during sandstorms, wind carries loads of sand. When the speed of ·wind decreases, huge amount of sand gets deposited. These mounds or hills of sand are called sand.dunes. There are different types of sand dunes
Barchan: Barchans are isolated, crescent shaped sand dunes. They have gentle slopes on the ·windward side and steep slopes on the leeward.side
Transverse Dunes: Transverse dunes are asymmetrical in shape. They are formed by alternate slow and fast winds that blow from the same direction.
Longitudinal Dunes: Longitudinal dunes are long narrow ridges of sand, which extend in a direction parallel to the prevailing winds. These dunes are called Seifs in Sahara.
Loess: The term loess refers to the deposits of fine silt and porous sand over a vast region.
Extensive loess deposits 'are found in Northern and Western China, the Pampas of Argentina, in Ukraine and in the Mississippi Valley of the United States.

Most erosion takes place due to the process of solution. When rain water mixes with carbondi- oxide and enters into a limestone region, it dissolves and destroys much of the limestone.
As a result, landforms such as Terra rossa, Lappies, sinkholes, swallow holes, dolines, uvalas, poljes, caves and caverns are formed. 
Terra Rossa (Italian term for Red soil): Deposition of red clay soil on the surface of the Earth is due to the dissolution of limestone content in rocks. The redness of the soil is due to the presence of iron oxide.
Lappies: When the joints oflimestone rocks are corrugated by groundwater, long furrows are formed and these are called LAPPIES.
Sinkhole: A funnel shaped depressions formed due to dissolution of limestone rock is called sinkholes. Their average depth ranges between three and nine meters.
Caves and Caverns: Caves and caverns are subterranean features of karst topography. Caves are hollows that are formed by the dissolution of limestone rocks when carbon di oxide in air turns into carbonic acid after its reaction with water. They vary in size and shape. Caverns are the caves with irregular floors. e.g., Guptadham caves in Western Bihar.
All types of deposits in the caves and caverns are collectively called speleothems which
(i) includes travertines,
(ii) tufa,
(iii) dripstones.
Swallow Holes, Uvalas, Dolines, Poljis are other erossional Features of karst regions predominant in other parts of the world.

Constructive Effects: Volcanic materials enrich the soil fertility that promotes agricultural activities. The hot volcanic region helps in generating geothermal energy. Many dormant and active volcanoes are the most attractive tourist spots of the world. Most of the volcanic materials are used as building materials.
Destructive Effects: Volcanic eruption causes Earthquakes, fast floods, mudslide and rock fall. Lava can travel very far and bum, bury or damage anything in its path: The large amount of dust and ash makes breathing hard and irritable. Volcanic eruptions can alter the weather conditions and disrupt transport (Iceland volcanic eruption) in and around the volcanic region.

The formation and deformation of landforms on the surface of the Earth is a continuous activity of two broad processes i.e. internal and external. These processes cause stress and deformation on Earth materials and finally bring changes on the surface of the Earth. These are referred as Geomorphic Processes.
The forces that act from the Earth's interior towards the Earth's surface are called Internal processes or Endogenetic processes. These forces build the landscape and create topographic relief.
The forces that act on the surface of the Earth due to natural agents like running water, glacier, wind, waves etc. are called External processes or Exogenetic processes. These external processes tear the landscape down into relatively low elevated plains.

(i) The history of humans is closely related to the history of the earth.
(ii) The earth contains geological, archaeological and biological records of historical times in its upper layers.
(iii) They are important for reconstructing the history of the earth and various living organisms.
(iv) The fossil bones of the human ancestors are embedded in the earth's layers.
(v) Palaeoanthropologists and archaeologists excavate the soil and rock layers on the earth and extract evidence about human ancestors.
(vi) These layers and the fossils are scientifically dated to study the various stages in human evolution and prehistory.
(vii) Through the gathered evidence they attempt to understand the evolution of human history and developments in a chronological order.·
(viii) The earth was formed approximately 4.54 billion years ago.
(ix) Gradually conditions emerged for the growth of organisms. Then plants and animals came into being and thereby foundation was laid for the evolution of humans. The long span of time in earth's history is divided into eras, periods and epochs by the Geologists. Thus the history of humans is closely related to the history of the earth.