geo l2 geomorphology_plate_tect_0.1
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Geomorphology
Continental drift
Sea-floor spreading
Plate tectonic theory
3 Theories
Super continent - PangaeaOcean – PanthalasaDuring Mid- Mesozoic, Pangaea broke up and drifted apart
Continental crust (SIAL rocks) float over Oceanic crust (SIMA rocks)
Driving force?
Continental drift theory
Zig-saw fit Similarity of rocks
Continental Drift theory
Fossil evidences Palaeo-climatic evidences
Continental drift theory
Convection cells
•Arthur Holmes:•Convection current theory•Convection cells – force behind drifting of continents
Continental drift
Sea-floor spreading
Plate tectonic theory
3 Theories
Sea-floor mapping
•During 1940s and 1950s•Diversity of ocean-floor•Submarine hills – guoyts – MOR –Trench
Questions:1) Ocean crust not older than mid-Mesozoic 2) Age increase away from MOR3) Sea-mounts deformed at trenches
Ocean floor mapping
1960s Harry Hass and Dietz answered question regarding ocean mapping using convection theory
revealed mystery of mid-oceanic ridge and trenches
Sea floor spreading Theory
Mid- Oceanic Ridge
MOR – Mid Oceanic Ridge
•Rising limb of current breaks the Ocean crust• Basaltic eruption•Accumulation of lava – ridge => MOR•New Oceanic crust•Divergent limb – expansion of ocean crust
MOR – Mid Oceanic Ridge
Trenches
•At trench Ocean floor destroyed – melted in mantle•Oceanic crust heavier than continental crust•Ocean floor act like conveyor belt•Ocean floor – cyclic process – 300 ml yrs
MOR - Trench
Mariana trench
Prelims 2006
Q. In which one of the following oceans the Diamantina Trench is located?a) Pacific Oceanb) Atlantic Oceanc) Indian Oceand) Arctic Ocean
Ans. C)
UPSC
Question
Diamantine trench
Palaeo-magentism
•Magnetism of rocks along MOR •Magnetometer -Magnetic parallel stripes– normal and reverse magnetic profile •1st Carlsberg ridge – Indian ocean
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 stripesAtlantic – 1.0 cm/ yearIndian – 1.5 cm/yearPacific – 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 1960sBased 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, NiOuter core = Fe, Ni + silicaMantle = OlivineOceans = basaltContinents = 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
geomorph
Fundamental
Rocks
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 - MOR Continental crust
Divergent Plate Boundary
Rift valley Nascent 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 desertBolivian plateauLake TiticacaMt. Aconcagua (highest peak)Mt. CotopaxiMt. ChimbrazoLake Maracaibo
Location near Andes
Rockies mountain range
Grand canyon – Colorado river
Columbia -snake plateauGrand canyon /Colorado plateauDeath valleyGreat 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 convergence
2. 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 PoBlack forest mountainsmountains: Pyrenees, ApenninesIslands of Mediterranean sea: Balearic, Sardinia, Corsica, Sicily, Malta, Cyprus
Straits: Bonifacio, Messina, MarmaraSea: 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 movement San 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 earthTrue mountains
Fold mountains
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
Europe India
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 plateauTibetan plateauColumbia plateauColorado plateauAnatolia Plateau (Turkey)
Deccan plateauKatanga plateauOzark plateau (USA)
Ethiopian highland
Continental plateau
Types of plateau
Glacial plateau
Grahwal plateauLaurentian plateau (Canada)
Columbia-snake plateau (USA)
Deccan PlateauShan plateau (Myanmar)
Lava plateau
Types 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 populationSichuan basin – rice cultivationShanghai – biggest port of China Wuhan – Iron and steelNanjing – textile, iron and steel Chengdu – oil and gasThree gorge damYun ho canal – connect Yangtze with Hwang He
Important locations
Euphrates- Tigris river, Iraq
Lake Van, Lake UrmiaImportant 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 regionPetroleum reserve at the mouthManaus – Iron ore, navigable plateau of Mato Grasso – gold reserve
Locations near Amazon river
Mississippi , USA
Temperate grasslands – PrairiesWheat, corn and cotton cultivationImportant cites: Kansas – agricultureSt. Pittsburg – iron and steelNew Orleans – port, ship building
Locations near Mississippi basin
Murray-Darling basin, Australia
Temperate grassland – downsWheat cultivationSheep rearing ,Animal husbandryWool 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
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