# 5. World Geography Part 1 Notes | Study RAS RPSC Prelims Preparation - Notes, Study Material & Tests - UPSC

## UPSC: 5. World Geography Part 1 Notes | Study RAS RPSC Prelims Preparation - Notes, Study Material & Tests - UPSC

The document 5. World Geography Part 1 Notes | Study RAS RPSC Prelims Preparation - Notes, Study Material & Tests - UPSC is a part of the UPSC Course RAS RPSC Prelims Preparation - Notes, Study Material & Tests.
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Geomorphology

Most of the knowledge we have about Earth’s deep interior comes from the fact that seismic waves penetrate the Earth and are recorded on the other side.  Earthquake ray paths and arrival times are more complex than illustrated in the animations, because velocity in the Earth does not simply increase with depth. Velocities generally increase downward, according to Snell’s Law, bending rays away from the vertical between layers on their downward journey; velocity generally decreases upward in layers, so that rays bend toward the vertical as they travel out of the Earth. Snell’s Law also dictates that rays bend abruptly inward at the mantle/outercore boundary (sharp velocity decrease in the liquid) and outward at the outer core/inner core boundary (sharp velocity increase).

Major Points to remember about P S and Love waves

•  P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to 'arrive' at a seismic station.
• The P wave can move through solid rock and fluids, like water or the liquid layers of the earth.
• P waves are also known as compressional waves.
• S wave or secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium.
• Travelling only through the crust, surface waves are of a lower frequency than body waves, and are easily distinguished on a seismogram as a result.

Earth’s Layers – Earth’s Composition

The Crust of Earth

It is the outermost and the thinnest layer of the earth’s surface, about 8 to 40 km thick. The crust varies greatly in thickness and composition – as small as 5 km thick in some places beneath the oceans, while under some mountain ranges it extends up to 70 km in depth.

The crust is made up of two layers­ an upper lighter layer called the Sial (Silicate + Aluminium) and a lower density layer called Sima (Silicate + Magnesium).The average density of this layer is 3 gm/cc.

The Mantle of Earth

This layer extends up to a depth of 2900 km.

Mantle is made up of 2 parts: Upper Mantle or Asthenosphere (up to about 500 km) and Lower Mantle. Asthenosphere is in a semi­molten plastic state, and it is thought that this enables the lithosphere to move about it. Within the asthenosphere, the velocity of seismic waves is considerably reduced (Called ‘Low Velocity

The line of separation between the mantle and the crust is known as Mohoviricic Discontinuity.

The Core of Earth

Beyond a depth of 2900 km lies the core of the earth. The outer core is 2100 km thick and is in molten form due to excessive heat out there. Inner core is 1370 km thick and is in plastic form due to the combined factors of excessive heat and pressure. It is made up of iron and nickel (Nife) and is responsible for earth’s magnetism. This layer has the maximum specific gravity. The temperatures in the earth’s core lie between 2200°c and 2750°c. The line of separation between the mantle and the core is called Gutenberg­Wiechert Discontinuity.

Earth Movements – Endogenetic Movements

The interaction of matter and temperature generates these forces or movements inside the earth’s crust. The earth movements are mainly of two types: diastrophism and the sudden movements.

The energy emanating from within the earth is the main force behind endogenic geomorphic processes.

This energy is mostly generated by radioactivity, rotational and tidal friction and primordial heat from the origin of the earth. This energy due to geothermal gradients and heat flow from within induces diastrophism and volcanism in the lithosphere.

Diastrophism

Diastrophism is the general term applied to slow bending, folding, warping and fracturing.

Wrap = make or become bent or twisted out of shape, typically from the action of heat or damp; make abnormal; distort.

All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. They include:

orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust;

epeirogenic processes involving uplift or warping of large parts of the earth’s crust;

Earthquakes involving local relatively minor movements;

Plate tectonics involving horizontal movements of crustal plates.

In the process of orogeny, the crust is severely deformed into folds. Due to epeirogeny, there may be simple deformation. Orogeny is a mountain building process whereas epeirogeny is continental building process.

Through the processes of orogeny, epeirogeny, earthquakes and plate tectonics, there can be faulting and fracturing of the crust. All these processes cause pressure, volume and temperature (PVT) changes which in turn induce metamorphism of rocks.

Epeirogenic or continent forming movements

In geology, Epeirogenic movement refers to upheavals or depressions of land exhibiting long wavelengths [undulations] and little folding.

The broad central parts of continents are called cartons, and are subject to epeirogeny.

The movement is caused by a set of forces acting along an Earth radius, such as those contributing to Isostacy and Faulting in the lithosphere

Epeirogenic or continent forming movements act along the radius of the earth; therefore, they are also called radial movements. Their direction may be towards (subsidence) or away (uplift) from the center. The results of such movements may be clearly defined in the relief.

Uplift

Raised beaches, elevated wave-cut terraces, sea caves and fossiliferous beds above sea level are evidences of uplift.

Raised beaches, some of them elevated as much as 15 m to 30 m above the present sea level, occur at several places along the Kathiawar, Nellore, and Thirunelveli coasts.

Several places which were on the sea some centuries ago are now a few miles inland. For example, Coringa near the mouth of the Godavari, Kaveripattinam in the Kaveri delta and Korkai on the coast of Thirunelveli, were all flourishing sea ports about 1,000 to 2,000 years ago.

Epeirogenic movement - uplift

Subsidence

Submerged forests and valleys as well as buildings are evidences of subsidence. In 1819, a part of the Rann of Kachchh was submerged as a result of an earthquake. Presence of peat and lignite beds below the sea level in Thirunelveli and the Sunderbans is an example of subsidence.

The Andamans and Nicobars have been isolated from the Arakan coast by submergence of the intervening land.

Epeirogenic movement - subsidence - arakan yomaEpeirogenic movement - subsidence - arakan yoma

On the east side of Bombay island, trees have been found embedded in mud about 4 m below low water mark. A similar submerged forest has also been noticed on the Thirunelveli coast in Tamil Nadu.

A large part of the Gulf of Mannar and Palk Strait is very shallow and has been submerged in geologically recent times. A part of the former town of Mahabalipuram near Chennai (Madras) is submerged in the sea.

Orgenic or the mountain-forming movements

Orogenic or the mountain-forming movements act tangentially to the earth surface, as in plate tectonics.

Tensions produces fissures (since this type of force acts away from a point in two directions) and compression produces folds (because this type of force acts towards a point from two or more directions). In the landforms so produced, the structurally identifiable units are difficult to recognise.

In general, diastrophic forces which have uplifted lands have predominated over forces which have lowered them.

Sudden Movements

These movements cause considerable deformation over a short span of time, and may be of two types.

Earthquake

It occurs when the surplus accumulated stress in rocks in the earth’s interior is relieved through the weak zones over the earth’s surface in form of kinetic energy of wave motion causing vibrations (at times devastating) on the earth’s surface. Such movements may result in uplift in coastal areas.

An earthquake in Chile (1822) caused a one-metre uplift in coastal areas.

An earthquake in New Zealand (1885) caused an uplift of upto 3 metres in some areas while some areas in Japan (1891) subsided by 6 metres after an earthquake.

Earthquakes may cause change in contours, change in river courses, ‘tsunamis’ (seismic waves created in sea by an earthquake, as they are called in Japan) which may cause shoreline changes, spectacular glacial surges (as in Alaska), landslides, soil creeps, mass wasting etc.

Volcanoes

Volcanism includes the movement of molten rock (magma) onto or toward the earth’s surface and also formation of many intrusive and extrusive volcanic forms.

A volcano is formed when the molten magma in the earth’s interior escapes through the crust by vents and fissures in the crust, accompanied by steam, gases (hydrogen sulphide, sulphur dioxide, hydrogen chloride, carbon dioxide) and pyroclastic material. Depending on chemical composition and viscosity of the lava, a volcano may take various forms.

Pyroclastic adjective of or denoting rock fragments or ash erupted by a volcano, especially as a hot, dense, destructive flow.

Continental Drift Theory – Tectonics

The continental drift theory is the theory that once all the continents were joined in a super-continent, which scientists call Pangaea. Over a vast period of time, the continents drifted apart to their current locations. Alfred Wegener first supported continental drift. Wegener’s explanation of continental drift in 1912 was that drifting occurred because of the earth’s rotation. Fossil records from separate continents, particularly on the outskirts of continents show the same species.

Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

Theory of seafloor spreading was proposed by Harry Hess.

Pale magnetism is the study of the record of the Earth's magnetic field in rocks, sediment, or archaeological materials. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form. Rocks when heated above curie point records the magnetic fields direction and preserve it for millions of years.

• Plate Tectonics – Indian Plate Movement

Plates are composed of lithosphere, about 100 km thick, which "float" on the ductile asthenosphere.

While the continents do indeed appear to drift, they do so only because they are part of larger plates that float and move horizontally on the upper mantle asthenosphere. The plates behave as rigid bodies with some ability to flex, but deformation occurs mainly along the boundaries between plates.

The plate boundaries can be identified because they are zones along which earthquakes occur. Plate interiors have much fewer earthquakes.

There are three types of plate boundaries:

1. Divergent Plate boundaries, where plates move away from each other.

2. Convergent Plate Boundaries, where plates move toward each other.

3. Transform Plate Boundaries, where plates slide past one another.

Divergent Plate Boundaries

These are oceanic ridges where new oceanic lithosphere is created by upwelling mantle that melts, resulting in basaltic magmas which intrude and erupt at the oceanic ridge to create new oceanic lithosphere and crust. As new oceanic lithosphere is created, it is pushed aside in opposite directions. Thus, the age of the oceanic crust becomes progressively older in both directions away from the ridge.

Because oceanic lithosphere may get sub ducted, the age of the ocean basins is relatively young. The oldest oceanic crust occurs farthest away from a ridge. In the Atlantic Ocean, the oldest oceanic crust occurs next to the North American and African continents and is about 160 million years old (Jurassic). In the Pacific Ocean, the oldest crust is also Jurassic in age, and occurs off the coast of Japan. Because the oceanic ridges are areas of young crust, there is very little sediment accumulation on the ridges. Sediment thickness increases in both directions away of the ridge, and is thickest where the oceanic crust is the oldest. Knowing the age of the crust and the distance from the ridge, the relative velocity of the plates can be determined. Relative plate velocities vary both for individual plates and for different plates. Sea floor topography is controlled by the age of the oceanic lithosphere and the rate of spreading.

If the spreading rate (relative velocity) is high, magma must be rising rapidly and the lithosphere is relatively hot beneath the ridge. Thus for fast spreading centers the ridge stands at higher elevations than for slow spreading centers. The rift valley at fast spreading centers is narrower than at slow spreading centers. As oceanic lithosphere moves away from the ridge, it cools and sinks deeper into the asthenosphere. Thus, the depth to the sea floor increases with increasing age away from the ridge.

Convergent Plate Boundaries

When a plate of dense oceanic lithosphere moving in one direction collides with a plate moving in the opposite direction, one of the plates sub ducts beneath the other. Where this occurs an oceanic trench forms on the sea floor and the sinking plate becomes a sub duction zone. The Wadati-Benioff Zone, a zone of earthquakes located along the subduction zone, identifies a subduction zone. The earthquakes may extend down to depths of 700 km before the sub ducting plate heats up and loses its ability to deform in a brittle fashion.

As the oceanic plate subducts, it begins to heat up causing the release water of water into the overlying mantle asthenosphere. The water reduces the melting temperature and results in the production of magmas. These magmas rise to the surface and create a volcanic arc parallel to the trench. If the subduction occurs beneath oceanic lithosphere, an island arc is produced at the surface (such as the Japanese islands, the Aleutian Islands, the Philippine islands, other Caribbean islands

Transform Plate Boundaries

Where lithospheric plates slide past one another in a horizontal manner, a transform fault is created. Earthquakes along such transform faults are shallow focus earthquakes.

Most transform faults occur where oceanic ridges are offset on the sea floor. Such offset occurs because spreading takes place on the spherical surface of the Earth, and some parts of a plate must be moving at a higher relative velocity than other parts One of the largest such transform boundaries occurs along the boundary of the North American and Pacific plates and is known as the San Andreas Fault. Here the transform fault cuts through continental lithosphere

Triple Junctions occur at points where three plates meet.

Hot Spots

Areas where rising plumes of hot mantle reach the surface, usually at locations far removed from plate boundaries are called hot spots. Because plates move relative to the underlying mantle, hot spots beneath oceanic lithosphere produce a chain of volcanoes. A volcano is active while it is over the vicinity of the hot spot, but eventually plate motion results in the volcano moving away from the plume and the volcano becomes extinct and begins to erode.

Because the Pacific Plate is one of the faster moving plates, this type of volcanism produces linear chains of islands and seamounts, such as the

• Hawaiian - Emperor chain, the Line
• Islands, the Marshall-Ellice Islands,
• and the Austral seamount chain Types of Mountains – Classification of Mountains

 GEOGRAPHY OF THE WORLD DEMOGRAPHY: Continent Density person/sq. km Asia 108 Europe 101 South America 21 Africa 20 North America 14 Oceania 3

 Urbanization by Continents: Continent Urbanization South America 78 Europe 74 North America 68

 Top 20 Countries by Area Country Area (lakh sq km) S. N Country Area (lakh sq km) Russia 170 11. Algeria 23 Canada 99 12. Dem. Rep of Congo 23 United States 96 13. Mexico 19 China 95 14. Saudi Arabia 19 Brazil 85 15. Indonesia 19 Australia 76 16. Libya 17 India 32 17. Iran 16 Argentina 27 18. Mongolia 15 Kazakhstan 27 19. Peru 12 Sudan 25 20. Chad 12

 Contributions of Important Geographer 1. Megalopolis concept Jean Gottman 2. Conurbation Concept, Wrote ‘Cities in Evolution’ Patrick Geddes 3. Polar Front Theory J. Bjerknes 4. Anticyclone term Sir Francis Galton 5. Equilibrium Theory of tides Issac Newton 6. Dynamic Theory of Tides Laplace 7. Progressive Wave Theory William Whewell 8. Canal Theory G. B. Airy 9. Stationary Wave Theory of Tides R. A. Harris 10. Process of Precipitation Bergeron 11. First used the term Ecology Tansley 12. Father of Ecology Haeckel 13. First used the term plate J. T Wilson 14. Coined the term Antecedent Stream J. W. Powell 15. Classification of clouds Luke Howard 16. Ice crystal Theory Tor Bergeron 17. Collision-Coalesce Theory George Simpson & Mason 18. Glacial Control Theory of Coral reef formation Daly 19. Subsidence Theory of Coral reef formation Darwin 20. Stand Still Theory of Coral reef Murray 21. Concept of grade G.K. Gilbert 22. Law of Stream number/Length R. E. Horton 23. Location Allocation Models P. Haggett 24. Law of Retail Gravitation W.J. Reilly 25. Concept of Threshold & Range B.J.L. Berry 26. Introduced the concept of Possibilism Lucien Febvre 27. Coined “Areal Differentiation” Hartshorne 28. General System Theory Ludwig von Bertalanffy 29. Developed Hythergraph G. Taylor 30. Polyconic Projection Ferdinand Hessler 31. Globular projection S.J. Fournier

 Minerals & Their Largest Producers 1. Graphite Madagascar 2. Gold South Africa, Australia 3. Platinum South Africa, Canada. 4. Chromium South Africa, Russia 5. Diamond South Africa, Republic of Congo & Australia 6. Zinc Canada, Australia 7. Uranium Canada, USA, Australia, Niger, France, South Africa 8. Nickel Canada, Russia, Australia, USA. 9. Coal China, USA, India, Russia 10. Steel China 11. Iron Ore China, Brazil, Australia.
 12 Cement China 13 Manganese China, South Africa, Australia. 14 Paper Canada 15 Hydro Power Canada, USA, (Norway highest %age User) 16 Tungsten China, Thailand, Korea 17 Asbestos Canada Russia, Zambia, Zimbabwe 18 Natural Gas Russia, Canada, Algeria, Iran 19 Flax Russia 20 Tantalum Australia 21 Bauxite Australia, Guinea, Jamaica & Brazil. 22 Lead Australia, China, US 23 Cadmium Canada 24 Antimony China 25 Uranium (Reser.) Australia, Kazakhstan, Canada, South Africa 26 Zirconium Australia Brazil 27 Titanium (Rutile) *Australia* 28 Iron China, Brazil, Australia 29 Copper Chile, United States, Canada, Armenia, Zambia, Zaire 30 Tin China, Indonesia, Peru, Brazil, Malaysia 31 Silver Mexico, Peru, Chile & Poland. 32 Mercury Spain, China, Italy. 33 Sulphur Mexico, USA & Poland 34 Rock Phosphate USA, Peru (Guano).

 Agricultural Commodities & Their Largest Producer 1. Milk India 2. Coffee Brazil, Vietnam 3. Tobacco China, turkey 4. Pork China 5. Rice (export) Thailand, Vietnam 6. Rice China, India 7. Banana India, Brazil 8. Banana (Export) Costa Rica, Jamaica, Honduras, Columbia 9. Maize USA, China 10. Wheat China 11. Cork Portugal 12. Palm Oil Malaysia 13. Fresh Water Fish Russia 14. Barley Germany, Canada, Russia, France 15. Tea (Exporter) Sri Lanka 16. Rubber Thailand, Indonesia, Malaysia 17. Paper USA 18. Pulp (Export) Canada 19. Paper (Export) Canada 20. Sugar India, Brazil, Cuba 21. Sugar (Export) Cuba
 22 Oil Palm Malaysia, Indonesia 23 Oil Palm (import) India 24 Cotton China, USA, India, Pakistan, Uzbekistan in that order. 25 Cotton (export) USA 26 Mangoes India 27 Manila Hemp (Abaca) Philippines (75%) 28 Raw Silk China, Japan, India, Korea. 29 Tobacco China, USA, India 30 Oranges USA, Brazil 31 Oats Russia 32 Millets India 33 Rye Russia 34 Sorghum USA 35 Pulses India 36 Sugarcane Brazil 37 Tea India, China 38 Dates Iran, Egypt 39 Olives Spain 40 Wine (Exporter) *Algeria* 41 Wine (Producer) Italy, France 42 Coconut Indonesia, Philippines, 43 Grapes Italy, France 44 Potato China 45 Soyabeens U.S.A, Brazil

 Sobriquets 1. Island of Cloves Zanzibar 2. Land of Lilies Canada 3. Land of Golden Fleece Australia 4. Port of Five Seas Moscow 5. Island of Pearls Bahrain 6. Hermit Kingdom Korea 7. Land of Golden Pagoda Yangoon (Myanmar) 8. City of Canals Venice 9. Holy Land Palestine 10. Herring Pond Atlantic 11. City of Golden Gate Sand Francisco 12. City of dreaming Spires Oxford 13. Land of Canals Netherlands 14. Empire city New York 15. Land of Cakes Scotland 16. Land of Eskimos Greenland 17. Island of Pearls Bahrain 18. Granite City Aberdeen, Scotland 19. Garden of England Kent 20. Cockpit of Europe Belgium
 21 City of brotherly Love Philadelphia 22 City of Magnificent Distances Washington DC 23 Gateway of tears Bab-el-Mandab 24 Textile Capital of Russia Ivanovo 25 Manchester of Japan Osaka (Textile) 26 Emerald City Ireland 27 The pearl of the Antilles Cuba

Highest Peaks In Various Regions/ Mountain Chain

 1 Africa Mt. Kilimanjaro 2 North America Mt. McKinley 3 Europe Mt. Elbrus 4 Antarctica Mt. Vinson 5 Asia Mt. Everest 6 Oceania Mt. Carstensz 7 South America Mt. Aconcagua 8 Australia Mt. Kosciusko 9 Urals Mt. Gora Naradnaya 10 Alps Mt. Mont Blanc 11 Andes Mt. Aconcagua 12 Rockies Mt. Elbert 13 Appalachians Mt. Mitchell 14 South West Asia (Elbruz Chain) Mt. Demavand

 Important Places/Regions & Their Locations 1. Llanos Tropical Grasslands of Venezuela 2. Campos Tropical grasslands of Brazil 3. Iberian Peninsula Spain 4. Katanga basin Democratic republic of Congo 5. Canterbury Plain Largest lowland area of New Zealand 6. Chaco / Gran Chaco Low, flat, arid region covering Argentina Paraguay & Bolivia. 7. Kra Peninsula Malaysia 8. Parana region Brazil –Largest producer of wheat, corn cotton 9. Matto grosso Thick jungle in west central brazil north of Bolivia. 10. Dogger bank Shallow fishing area in north sea, 100km off UK 11. Grand bank Shallow fishing area off new foundland, Canada 12. Georges bank Near bay of fundy & Gulf of Maine 13. Nordic Countries Norway, Iceland, Greenland, Denmark. 14. Ob, Yenisey & Lena Major rivers of Russia 15. Sarawak, Sabah, Labuan These three states make up east Malaysia. 16. Yucatan Peninsula Mexico 17. Ozark Plateau heavily forested upland region, between the Missouri and Arkansas rivers 18. Sinai Peninsula In north eastern Egypt.

 Miscellaneous Data of Various Nations S. No. Country/ Urban Hydro Nuclear Thermal Forest Region % Elect % % % % 1. Canada 75 60 2. USA 10 25 3. Britain 24 4. Italy 50 5. Norway 90 6. New Zealand 75 7. Switzerland 74 8. Japan 76 32 9. France 77 10. Lithuania 78 11. Germany 30 12. Australia 80 90 13. S. E. Asia 20 14. Russia 60
The document 5. World Geography Part 1 Notes | Study RAS RPSC Prelims Preparation - Notes, Study Material & Tests - UPSC is a part of the UPSC Course RAS RPSC Prelims Preparation - Notes, Study Material & Tests.
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