Chapter 1 GEOGRAPHY AS A DISCIPLINE
You have studied geography as one of the components of your Social Science course upto the secondary stage. You are already aware of some of the phenomena of geographical nature in the world and its different parts. Now, you will study ‘Geography’ as an independent subject and learn about the physical environment of the earth, human activities and their interactive relationships. Therefore, a pertinent question you can ask at this stage is — Why should we study geography? We live on the surface of the earth. Our lives are affected by our surroundings in many ways. We depend on the resources to sustain ourselves in the surrounding areas. Primitive societies subsisted on ‘natural means of subsistence’, i.e. edible plants and animals. With the passage of time, we developed technologies and started producing our food using natural resources such as land, soil and water. We adjusted our food habits and clothing according to the prevailing weather conditions. There are variations in the natural resource base, technological development, adaptation with and modification of physical environment, social organisations and cultural development. As a student of geography, you should be curious to know about all the phenomena which vary over space. You learn about the diverse lands and people. You should also be interested in understanding the changes which have taken place over time. Geography equips you to appreciate diversity and investigate into the causes responsible for creating such variations over time and space. You will develop skills to understand the globe converted into maps and have a visual sense
of the earth’s surface. The understanding and the skills obtained in modern scientific techniques such as GIS and computer cartography equip you to meaningfully contribute to the national endeavour for development.
Now the next question which you may like to ask is — What is geography? You know that earth is our home. It is also the home of many other creatures, big and small, which live on the earth and sustain. The earth’s surface is not uniform. It has variations in its physical features. There are mountains, hills, valleys, plains, plateaus, oceans, lakes, deserts and wilderness. There are variations in its social and cultural features too. There are villages, cities, roads, railways, ports, markets and many other elements created by human beings across the entire period of their cultural development.
This variation provides a clue to the understanding of the relationship between the physical environment and social/cultural features. The physical environment has provided the stage, on which human societies enacted the drama of their creative skills with the tools and techniques which they invented and evolved in the process of their cultural development. Now, you should be able to attempt the answer of the question posed earlier as to “What is geography”? In very simple words, it can be said that geography is the description of the earth. The term geography was first coined by Eratosthenese, a Greek scholar (276-194 BC.). The word has been derived from two roots from Greek language geo (earth) and graphos (description).
Class 12 Geography Important Questions Chapter 11 अंतरराष्ट्रीय व्यापार
Class 12 Geography Important Questions Chapter 10 परिवहन एवं संचार
Class 12 Geography Important Questions Chapter 9 भारत के संदर्भ में नियोजन और सततपोषणीय विकास
Class 12 Geography Important Questions Chapter 8 निर्माण उद्योग
Class 12 Geography Important Questions Chapter 7 खनिज तथा ऊर्जा संसाधन
Class 12 Geography Important Questions Chapter 6 जल संसाधन
\Class 12 Geography Important Questions Chapter 5 भू संसाधन तथा कृषि
\Class 12 Geography Important Questions Chapter 4 मानव बस्तियां
Class 12 Geography Important Questions Chapter 3 मानव विकास
Class 12 Geography Important Questions Chapter 2 प्रवास प्रकार कारण और परिणाम
Class 12 Geography Important Questions Chapter 1 जनसंख्या वितरण घनत्व वृद्धि और संगठन
Class 12 Geography Important Questions Chapter 10 मानव बस्ती
Class 12 Geography Important Questions Chapter 8 परिवहन एवं संचार
Class 12 Geography Important Questions Chapter 9 अंतर्राष्ट्रीय व्यापार
Class 12 Geography Important Questions Chapter 7 तृतीयक और चतुर्थ क्रियाकलाप
Class 12 Geography Important Questions Chapter 6 द्वितीयक क्रियाएँ
Class 12 Geography Important Questions Chapter 5 प्राथमिक क्रियाएँ
Class 12 Geography Important Questions Chapter 4 मानव विकास
Class 12 Geography Important Questions Chapter 3 जनसंख्या संगठन
Class 12 Geography Important Questions Chapter 2 - विश्व जनसंख्या वितरण, घनत्व और वृद्धि
Class 12 Geography Important Questions Chapter 1 मानव भूगोल प्रकृति एवं विषय क्षेत्
Chapter 2 : THE ORIGIN AND EVOLUTION OF THE EARTH
Do you remember the nursery rhyme “...Twinkle, twinkle little star...”?
Starry nights have always attracted us since the childhood. You may also have thought of these stars and had numerous questions in your mind. Questions such as how many stars are there in the sky? How did they come into existence? Can one reach the end of the sky? May be many more such questions are still there in your mind. In this chapter, you will learn how these “twinkling little stars” were formed. With that you will eventually also read the story of origin and evolution of the earth.
EARLY THEORIES Origin of the Earth
A large number of hypotheses were put forth by different philosophers and scientists regarding the origin of the earth. One of the earlier and popular arguments was by German philosopher Immanuel Kant. Mathematician Laplace revised it in 1796. It is known as Nebular Hypothesis. The hypothesis considered that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating. Later in 1900, Chamberlain and Moulton considered that a wandering star approached the sun. As a result, a cigar-shaped extension of material was separated from the solar surface. As the passing star moved away, the material separated from the solar surface continued to revolve around the sun and it slowly condensed into planets. Sir James Jeans and later Sir Harold Jeffrey supported this argument. At a later date, the arguments considered of a companion to the sun to have been coexisting. These arguments are called binary theories. In 1950, Otto Schmidt in Russia and Carl Weizascar in Germany somewhat revised the ‘nebular hypothesis’, though differing in details. They considered that the sun was surrounded by solar nebula containing mostly the hydrogen and helium along with what may be termed as dust. The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion.
However, scientists in later period took up the problems of origin of universe rather than that of just the earth or the planets.
MODERN THEORIES Origin of the Universe
The most popular argument regarding the origin of the universe is the Big Bang Theory. It is also called expanding universe hypothesis. Edwin Hubble, in 1920, provided evidence that the universe is expanding. As time passes, galaxies move further and further apart. You can experiment and find what does the expanding universe mean. Take a balloon and mark some points on it to represent the galaxies. Now, if you start inflating the balloon, the points marked on the balloon will appear to be moving away from each other as the balloon expands. Similarly, the distance between the galaxies is also found to be increasing and thereby, the universe is considered to be expanding. However, you will find that besides the increase in the distances between the points on the
Class 12 Geography MCQs Chapter – 10 मानव बस्ती
Class 12 Geography MCQs Chapter – 9 अंतर्राष्ट्रीय व्यापार
Class 12 Geography MCQs Chapter – 8 परिवहन एवं संचार
Class 12 Geography MCQs Chapter – 7 तृतीयक और चतुर्थ क्रियाकलाप
Class 12 Geography MCQs Chapter – 6 द्वितीयक क्रियाएँ
Class 12 Geography MCQs Chapter – 5 प्राथमिक क्रियाएँ
Class 12 Geography MCQs Chapter – 4 मानव विकास
Class 12 Geography MCQs Chapter – 3 जनसंख्या संगठन
Class 12 Geography MCQs Chapter – 2 विश्व जनसंख्या वितरण, घनत्व और वृद्धि
Class 12 Geography MCQs Chapter – 1 मानव भूगोल प्रकृति एवं विषय क्षेत्र
Class 12 Geography MCQs Chapter – 12 भौगोलिक परिप्रेक्ष्य में चयनित कुछ मुद्दे एवं समस्यायएं
Class 12 Geography MCQs Chapter – 11 अंतरराष्ट्रीय व्यापार
Class 12 Geography MCQs Chapter – 10 परिवहन एवं संचार
Class 12 Geography MCQs Chapter – 9 भारत के संदर्भ में नियोजन और सततपोषणीय विकास
Class 12 Geography MCQs Chapter – 8 निर्माण उद्योग
Class 12 Geography MCQs Chapter – 7 खनिज तथा ऊर्जा संसाधन
Class 12 Geography MCQs Chapter – 6 जल संसाधन
Class 12 Geography MCQs Chapter – 5 भू संसाधन तथा कृषि
Class 12 Geography MCQs Chapter – 4 मानव बस्तियां
Class 12 Geography MCQs Chapter – 3 मानव विकास
Class 12 Geography MCQs Chapter – 2 प्रवास प्रकार कारण और परिणाम
Class 12 Geography MCQs Chapter – 1 जनसंख्या वितरण घनत्व वृद्धि और संगठन
Chapter 3 - INTERIOR OF THE EARTH
What do you imagine about the nature of the earth? Do you imagine it to be a solid ball like cricket ball or a hollow ball with a thick cover of rocks i.e. lithosphere? Have you ever seen photographs or images of a volcanic eruption on the television screen? Can you recollect the emergence of hot molten lava, dust, smoke, fire and magma flowing out of the volcanic crater? The interior of the earth can be understood only by indirect evidences as neither any one has nor any one can reach the interior of the earth.
The configuration of the surface of the earth is largely a product of the processes operating in the interior of the earth. Exogenic as well as endogenic processes are constantly shaping the landscape. A proper understanding of the physiographic character of a region remains incomplete if the effects of endogenic processes are ignored. Human life is largely influenced by the physiography of the region. Therefore, it is necessary that one gets acquainted with the forces that influence landscape development. To understand why the earth shakes or how a tsunami wave is generated, it is necessary that we know certain details of the interior of the earth. In the previous chapter, you have noted that the earth-forming materials have been distributed in the form of layers from the crust to the core. It is interesting to know how scientists have gathered information about these layers and what are the characteristics of each of these layers. This is exactly what this chapter deals with.
SOURCES OF INFORMATION ABOUT THE INTERIOR
The earth’s radius is 6,370 km. No one can reach the centre of the earth and make observations or collect samples of the material. Under such conditions, you may wonder how scientists tell us about the earth’s interior and the type of materials that exist at such depths. Most of our knowledge about the interior of the earth is largely based on estimates and inferences. Yet, a part of the information is obtained through direct observations and analysis of materials.
Direct Sources
The most easily available solid earth material is surface rock or the rocks we get from mining areas. Gold mines in South Africa are as deep as 3 - 4 km. Going beyond this depth is not possible as it is very hot at this depth. Besides mining, scientists have taken up a number of projects to penetrate deeper depths to explore the conditions in the crustal portions. Scientists world over are working on two major projects such as “Deep Ocean Drilling Project” and “Integrated Ocean Drilling Project”. The deepest drill at Kola, in Arctic Ocean, has so far reached a depth of 12 km. This and many deep drilling projects have provided large volume of information through the analysis of materials collected at different depths.
Volcanic eruption forms another source of obtaining direct information. As and when the molten material (magma) is thrown onto the surface of the earth, during volcanic eruption it becomes available for laboratory analysis. However, it is difficult to ascertain the depth of the source of such magma.
In the previous chapter, you have studied the interior of the earth. You are already familiar with the world map. You know that continents cover 29 per cent of the surface of the earth and the remainder is under oceanic waters. The positions of the continents and the ocean bodies, as we see them in the map, have not been the same in the past. Moreover, it is now a well-accepted fact that oceans and continents will not continue to enjoy their present positions in times to come. If this is so, the question arises what were their positions in the past? Why and how do they change their positions? Even if it is true that the continents and oceans have changed and are changing their positions, you may wonder as to how scientists know this. How have they determined their earlier positions? You will find the answers to some of these and related questions in this chapter.
CONTINENTAL DRIFT
Observe the shape of the coastline of the Atlantic Ocean. You will be surprised by the symmetry of the coastlines on either side of the ocean. No wonder, many scientists thought of this similarity and considered the possibility of the two Americas, Europe and Africa, to be once joined together. From the known records of the history of science, it was Abraham Ortelius, a Dutch map maker, who first proposed such a possibility as early as 1596. Antonio Pellegrini drew a map showing the three continents together. However, it was Alfred Wegener—a German meteorologist who put forth a comprehensive argument in the form of “the continental drift
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CBSE Class 12 Geography Sample Paper - 7
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Class 12 Geography Notes Chapter 22 Geographical Perspective on Selected Issues and Problems
Class 12 Geography Notes Chapter 21 International Trade
Class 12 Geography Notes Chapter 20 Transport and Communication
Class 12 Geography Notes Chapter 19 Planning and Sustainable Development In Indian Context
Class 12 Geography Notes Chapter 18 Manufacturing Industries
Class 12 Geography Notes Chapter 17 Mineral and Energy Resources
Class 12 Geography Notes Chapter 16 Water Resources
Class 12 Geography Notes Chapter 15 Land Resources and Agriculture
Chapter 4 - DISTRIBUTION OF OCEANS AND CONTINENTS
theory” in 1912. This was regarding the distribution of the oceans and the continents.
According to Wegener, all the continents formed a single continental mass and mega ocean surrounded the same. The super continent was named PANGAEA, which meant all earth. The mega-ocean was called PANTHALASSA, meaning all water. He argued that, around 200 million years ago, the super continent, Pangaea, began to split. Pangaea first broke into two large continental masses as Laurasia and Gondwanaland forming the northern and southern components respectively. Subsequently, Laurasia and Gondwanaland continued to break into various smaller continents that exist today. A variety of evidence was offered in support of the continental drift. Some of these are given below.
Evidence in Support of the Continental Drift
The Matching of Continents (Jig-Saw-Fit)
The shorelines of Africa and South America facing each other have a remarkable and unmistakable match. It may be noted that a map produced using a computer programme to find the best fit of the Atlantic margin was presented by Bullard in 1964. It proved to be quite perfect. The match was tried at 1,000- fathom line instead of the present shoreline.
Rocks of Same Age Across the Oceans
The radiometric dating methods developed in the recent period have facilitated correlating the rock formation from different continents across
Class 12 Geography Notes Chapter 14 Human Settlements
Class 12 Geography Notes Chapter 13 Human Development
Class 12 Geography Notes Chapter 12 Migration
Class 12 Geography Notes Chapter 11 Population Distribution Density Growth and Composition
Class 12 Geography Notes Chapter 10 Human Settlements
Class 12 Geography Notes Chapter 9 International Trade
Class 12 Geography Notes Chapter 8 Transport and Communication
Class 12 Geography Notes Chapter 7 Tertiary and Quaternary Activities
Class 12 Geography Notes Chapter 6 Secondary Activities
Class 12 Geography Notes Chapter 5 Primary Activities
Class 12 Geography Notes Chapter 4 Human Development
Class 12 Geography Notes Chapter 3 Population Composition
Class 12 Geography Notes Chapter 2 The World Population
Class 12 Geography Notes Chapter 1 Human Geography
CBSE Class 12 Geography Sample Paper
GEOGRAPHY (029) CLASS XII 2015-2016
Chapter 5 - MINERALS AND ROCKS
he earth is composed of various kinds of elements. These elements are in solid form in the outer layer of the earth and in hot and molten form in the interior.
About 98 per cent of the total crust of the earth is composed of eight elements like oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium, and the rest is constituted by titanium, hydrogen, phosphorous, manganese, sulphur, carbon, nickel and other elements.
The elements in the earths’ crust are rarely found exclusively but are usually combined with other elements to make various substances. These substances are recognised as minerals.
Thus, a mineral is a naturally occurring organic and inorganic substance, having an orderly atomic structure and a definite chemical composition and physical properties. A mineral is composed of two or more elements. But, sometimes single element minerals like sulphur, copper, silver, gold, graphite etc. are found.
Though the number of elements making up the lithosphere are limited they are combined in many different ways to make up many varieties of minerals. There are at least 2,000 minerals that have been named and identified in the earth crust; but almost all the commonly occurring ones are related to six major mineral groups that are known as major rock forming minerals.
The basic source of all minerals is the hot magma in the interior of the earth. When magma cools, crystals of minerals appear and a systematic series of minerals are formed in sequence to solidify so as to form rocks. Minerals such as coal, petroleum and natural gas are organic substances found in solid, liquid and gaseous forms respectively.
A brief information about some important minerals in terms of their nature and physical characteristics is given below :
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