Geographic l2
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Transcript of Geographic l2
Geomagnetism
• Vine and mattheus • Molten lava get polarity
geomagnetic field of that period -Solidify
• Ocean floor – magnetic tape
Palaeo-magentism
conclusion1) Periodic reversal of magnetic field of the earth2) Rate of sea-floor spreading decided by age + distance between two equal magnetic stripes• Atlantic – 1.0 cm/ year• Indian – 1.5 cm/year• Pacific – 6.0 cm/year
Palaeo-magnetism
Continental drift Sea-floor spreading Plate tectonic theory
3 Theories
• Unanswered questions – • Formation of fold mountains?• Reason for earth quake?• Reason for volcanism on land?
Plate tectonic Theory
• Work of many scientists from different discipline
• Came out in 1960s• Based on 2 scientific evidences1) sea-floor spreading2) Palaeo-magnetismThe most latest and accepted theory
Plate tectonic theory
• Crust and upper part of mantle => lithosphere
• Asthenosphere = unique mechanical rigidity, semi-molten, plastic
• Lithosphere float over Asthenosphere
• Lithosphere is not continuous, broken, known as plates
Plates
• J.T Wilson termed –’Plate’ (litho, 100km)
• 3 types of plates:• Entirely oceanic,
entirely continental and both continental and oceanic
• 6 major and 20 minor plates
plates
Plates of the world
• Inner core= Fe, Ni• Outer core = Fe, Ni + silica• Mantle = Olivine• Oceans = basalt• Continents = granite and andesite
Chemical composition of Interior
Location of rocks
Example Property
Mantle Olivine highly fluid Heaviest
Oceanic crust
Basalt FluidHeavy
Continental crust
Andesite less mobileLighter
Continental crust
Granite least mobileLightest
geomorphFundam
entalRocks
Olivine
Basalt
Andesite
Granite
Burning and Melting of rocks
Divergent Boundary
Convergent Boundary
Transverse Boundary
Plate Interactions
• Ascending limb of convection current – below O /C
• Below ocean – MOR• Below continent – rift
valley, nascent sea
Divergent Plate Boundary
Oceanic crust - MORContinental crust
Divergent Plate Boundary
Rift valley
Nascen
t sea
Ocean
Phases of Divergent continental crust
Phases of Divergent continental crust
The Great African rift valley
Red sea – Nascent sea
Africa after 10 ml years
Knot of Plates
Knot of plates
Lakes and Nile river -African rift valley
African lakes
River Nile
• From 2011 on Blue Nile• Africa’s largest
hydroelectric dam• Egypt to lose water share
+ hydro electricity from Aswan
• Egypt showed reservation but Ethiopia did not pay heed
• Egypt ready for military intervention
• British treaties between Egypt and Sudan
Grand Renaissance dam, Ethiopia
• Nubian desert• Eastern desert• Namib desert• Lake Victoria• Lake Malawi• Lake Turkana• Lake chad• River Congo
• River Niger• Mt. Kilimanjaro • Katanga plateau• Grain coast• Ivory coast• Gold coast• Slave coast• Darfur
Locations in Africa
Prelims 2000
Q. Which one of the following lakes form an international boundary between Tanzania and Uganda?a) Chadb) Malawic) Victoriad) Zambezi
Ans.
UPSC
Question
O-O
•Island arc
O-C•Volcanic mountains
C-C•Fold mountains
Convergent Plate Boundary
O-O convergence
• Islands in S E Asia• Indo- Austral
plate and Eurasian plate movement
• Volcano + EQ
Island Arc
Mains 2014
Q. Explain the formation of thousands of islands in Indonesia and Philippines archipelago? (10)
UPSC
Question
Islands of South East Asia
Islands of Indian Ocean
O-O
•Island arc
O-C•Volcanic mountains
C-C•Fold mountains
Convergent Plate Boundary
O-C convergence
EX.• Andes ,
Rockies, Atlas mountain
• From Andes => andesitic rocks
• Volcano + EQ
Volcanic Mountains
Andes mountain range
• Atacama desert• Bolivian plateau• Lake Titicaca• Mt. Aconcagua (highest peak)• Mt. Cotopaxi• Mt. Chimbrazo• Lake Maracaibo
Location near Andes
Rockies mountain range
Grand canyon – Colorado river
• Columbia -snake plateau• Grand canyon /Colorado plateau• Death valley• Great salt lake• Mt.Logan (highest peak of rockies)• Mt. Mckinley (highest peak of N. America) in
Alaskan range
Locations near Rockies
Prelims 2005
Q. Where is the volcanic mountain. Mount. St. Helens is located?
a) Chileb) Japanc) Philippinesd) USAAns. D)
UPSC
Question
Mains2014
Q. why are the world’s fold mountain systems located along the margins of continents? Bring out the association between global distribution of fold -mountains and earthquakes and volcanoes (10)
UPSC
Question
O-O
•Island arc
O-C•Volcanic mountains
C-C•Fold mountains
Convergent Plate Boundary
C-C convergence
• Not located on coast
• No volcanism • But powerful EQ
• Ex. • Himalayas, Alps,
Urals
Continental Mountains
1. O-C convergence2. C-C convergence
Himalayan formation
Karakoram range
Alps mountain range
Physical map of Europe
Bosporus strait
City RiverParis SeineFrankfurt RhineVenice PoVienna, Budapest, Belgrade
Danube
Kiev DniesterBerlin Elbe
Cities of Europe
• Rivers: Rhone, Danube and Po• Black forest mountains• mountains: Pyrenees, Apennines• Islands of Mediterranean sea: Balearic,
Sardinia, Corsica, Sicily, Malta, Cyprus• Straits: Bonifacio, Messina, Marmara• Sea: Tyrrhenian, Adriatic, Ionian and Aegean
Locations near Alps
• When two plates slip pass-off each other
• No mountains but seismic activity
• San Andreas fault in California, USA
Transform Boundary
Plate movementSan Andreas fault, USA
San Andreas fault
• Early atmosphere – thin layer of H, He
• Numerous meteorites attack on earth
• Break the surface• Underlying lava
eruption• First oceanic crust
formed
Meteorite Impact theory
Continental drift Sea-floor spreading Plate tectonic theory
3 Theories
Prelims 2011
Q. Between India and East Asia, the navigation time and distance can be greatly reduced by which of the following?a) Deepening Malacca
strait between Indonesia and Malaysia
b) Opening a new canal across Kra Isthmus between gulf of Siam and Andaman sea
UPSC
Question
Mountains
Plateaus
Plains
Landforms on earth
mountains
Fold mountains
Block mountains
Types of mountains
Fold mountains
Mountains created due to convergent boundaries of both
1) O-C (Rockies, Andes) 2) C-C (Himalayas,
Alps)Compressive forces of platesYoungest mountains on earth
True mountains
Fold mountai
ns
Geomorph
1)Extensive mountain chain3) Great heights4) Formed along unstable parts of the earth5) Sedimentary deposits of marine origin (C-C)
Characteristics of Fold mountains
• Pull of descending limb of convection current
• great pressure of compressive force exerted by the convection cells
Phases of mountain building
• Elongated, narrow depression on continental margins
• Here sediments from both land and ocean accumulate
• Under intense pressure, sediments of geo-syncline folded
Geo-syncline
• Sediments from continental crusts of both plates + geo-syncline folded
• Because of sediments of geo-syncline – marine origin
C-C collision
Fold mountains of the world
1) Alaska range2) Rockies3) Andes4) Atlas mountains5) Pyrenees6) Caucasus 7) Taurus 8) Elburz and Zagros
9) Hindukush10) Kirthar range11) Kunlun Shan12) Urals mountains13) Appalachian mountains14) Great Dividing Range
List of mountains to locate
• understanding of the origin and evolution of earth’s crust.
• At the time of the formation of the earth crust, first basaltic crust of ocean - breaking and melting - a lighter continental crust developed.
• collide with one another = a larger land mass.• The joints = fold-mountains.
Importance of mountain building process
mountains
Fold mountains
Block mountains
Types of mountains
Block mountains formation
Block mountains formation
• Fault-block mt.• Due to forces within
interior of the earth• Uplifted part = horst• depressed part =
Grabben• Horst => block
mountains• Grabben => rift valley
Block mountains
EuropeIndia
Example of block mountains
Meaning:Table land, upland, higher than surrounding areas
• Raised land during mountains building process• Eroded
mountains• Eroded due to
glaciers• Deposition from
lava, wind
Plateaus
Intermontane plateau
• Bolivia plateau• Tibetan plateau• Columbia plateau• Colorado plateau• Anatolia Plateau
(Turkey)
• Deccan plateau• Katanga plateau• Ozark plateau
(USA)• Ethiopian
highland
Continental plateau
Types of plateau
Glacial plateau• Grahwal
plateau• Laurentian
plateau (Canada)
• Columbia-snake plateau (USA)• Deccan Plateau• Shan plateau
(Myanmar)
Lava plateauTypes of Plateau
• Origin of River Congo and Zambezi
• Dense equatorial forest• Known for resources- Gold, diamonds, Copper
Katanga Plateau
• Granite• Less mobile,
cannot move upward
• Backbone of fold mountains
Batholith
Plains
• Meaning• Flat areas with low
heights• Best for human
habitation• Most populated areas
of the world – alluvial plains of rivers
• Depositional plains- Rivers- Sea (sub-merged coast)
• Erosional plains- Erosion of plateau
Asia Europe
Africa
South America
North America
Indus Danube
Nile Amazon
Mississippi – Missouri
Ganga –Brahmaputra
Rhine Congo Parana- Paraguay
Colorado
Yangtze (China) Rhone Niger St. Lawrence
Hwang He (China)
Po Zambezi
Yukon
Ob- Irtysh (Russia)
Don Orange
Mackenzie
Mekong (SE Asia)
Euphrates - Tigris
Important river basins of the world
Yangtze river, China
• Navigable river – 35% of China’s population• Sichuan basin – rice cultivation• Shanghai – biggest port of China• Wuhan – Iron and steel• Nanjing – textile, iron and steel • Chengdu – oil and gas• Three gorge dam• Yun ho canal – connect Yangtze with Hwang He
Important locations
Euphrates- Tigris river, Iraq
• Lake Van, • Lake Urmia• Important centers in Iraq:• Baghdad, Mosul, Kirkuk, Al Basra
Locations near Euphrates-Tigris
Amazon river, Brazil
• Largest, 2nd longest river • Selvas – equatorial rain forest • Tin, rubber in Selvas • Sertao – ranching region• Petroleum reserve at the mouth• Manaus – Iron ore, navigable • plateau of Mato Grasso – gold reserve
Locations near Amazon river
Mississippi , USA
• Temperate grasslands – Prairies• Wheat, corn and cotton cultivation• Important cites: • Kansas – agriculture• St. Pittsburg – iron and steel• New Orleans – port, ship building
Locations near Mississippi basin
Murray-Darling basin, Australia
• Temperate grassland – downs• Wheat cultivation• Sheep rearing ,Animal husbandry• Wool and dairy production
Location near Murray-darling basin
Continental drift theory -> sea-floor spreading theory -> plate tectonic theory
Landforms on earthMountains (fold and block)
PlateausPlains