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You are here: Home / Geography / 11th Standard Geography NCERT – Fundamental of Physical Geography

11th Standard Geography NCERT – Fundamental of Physical Geography

April 30, 2020 by BureaucratONE Leave a Comment Last Updated July 22, 2020

This post is incomplete and needs formating

.he Origin and evolution of the earth

  • Origin of Universe - Big Bang Theory a.k.a expanding universe theory by Edwin Hubble
    • "Tiny ball" of singular atom with unimaginable small volume, infinite temperature and infinite density
    • Big bang happened before 13.7 billion years
    • Tiny ball expanded rapidly but now slowed
    • Some energy transformed into matter
    • Within 3 minutes atom formed
    • Within 3 lakh years temperature dropped to 4500K
    • Alternate theory is Hoyle's concept of steady state
  • The Galaxy Formation
    • Uneven mass distribution lead to gravitational pull
    • This pull formed galaxies accumulation of hydrogen cloud called nebula
    • Diameter - 80000-150000 light years
    • Localised clump of hydrogen gas grows into starts - 5-6 billion years ago
  • Formation of Planets
    • Gravity in stars form core
    1. Gas condenses into planetesimals over core
    • Large number of small planetesimals becomes fewer number of large bodies called planets
  • Our solar system
    • 8 planets, 63 moons
    • Sun - 5-5.6 billion years ago
    • Planets - 4.6 billion years
    • Mercury, venus, earth and mars - inner planets and terrestrial
    • Jupiter, saturn, uranus, neptune - jovian or jupiter like or gaseous or outer planets
    • Why terrestrial planets solid
      • Close to sun - so hot - so gases condense easily
      • Solar winds ripped off gases
      • Smaller size - so low gravity - so can't hold gases
  • The moon
    • Giant impact or the big splat
    • A body 1-3 times size of mars collided earth and a piece from earth formed moon
  • Evolution of the Earth
    • Lithosphere - gravity - so pressure - so heat - so dense material sunk to core - outer cooled and solidified - differentiation
    • Atmosphere and hydrosphere
      • Stage 1 - loss of primordial atmosphere - H and He
      • Stage 2 - hot interior - degassing
      • Stage 3 - photosynthesis
    • 3.8 billion years ago life started

3.INTERIOR OF THE EARTH

  • Exogenic and endogenic processes are constantly shaping the landscape
  • Sources of info about the interior
    • Direct
      • Surface rocks and rocks from mining
      • Two major project - deep ocean drilling project and integrated ocean drilling project
      • Deepest drill at Kola, Arctic Ocean - 12km
      • Volcanic eruption
    • Indirect
      • Meteors
      • "Gravity anomaly" - greater at pole and lesser at equator
      • Magnetic field
      • Seismic activity
  • Earthquake
    • Rock along fault lines overcomes the friction from overlying strata and moves apart causing release of energy.
    • The point where energy is released is focus or hypocentre
    • The point above is epicentre
  • Earthquake waves
    •  lithosphere 200km
    • Seismograph records waves reaching surface
    • Two types
      • Body waves
        • P waves - fastest to arrive at surface/similar to sound wave/a.k.a primary wave/solid, liquid, gas
          • Parallel to propagation so density difference by squeezing and stretching
        • S waves - secondary wave/arrives at lag/solid only
          • Perpendicular to propagation in vertical plane so troughs and crust
      • Surface waves
        • Body waves interact with surface rocks to form surface waves
        • Most damaging
  • Emergency of shadow zone
    • Where waves not reported
    • 105* - 145* from epicentre - for both P and S
    • 145* and beyond - no S but only P
  • Types of earth quake
    • Tectonic - sliding of rock along a fault plane
    • Volcanic
    • Collapse - intense mining
    • Explosion - nuclear or chemical explosion
    • Reservoir induced earthquake
  • Measuring Earthquakes
    • Magnitude scale - Richter scale - 1-10
    • Intensity scale - Mercalli - 1-12
  • Frequency of earth quake
    • 8+ once in 1 or 2 year
    • Tiny types - every minute
  • Structure of the earth
    • Image result for interior of earth
  • The crust
    • Oceanic - 5km
    • Continental - 30km/ himalayas - 70km/denser than oceanic
    • Density - 3g/cm3
  • The mantle
    • From moho's discontinuity to 2900km
    • Upper portion - astheno(weak)sphere -upto 400km - molten rock comes from here
    • Crust + upper mantle = lithosphere - 10-200km
    • 3.4g/cm3
  • The core
    • Outer core liquid - 5g/cm3
    • Inner core solid  - 13g/cm3
    • NIFE
  • Volcanos and Volcanic Landforms
    • Asthenosphere - magma comes out and becomes lava
    • Types
Image result for types of volcanoes
  • Shield Volcanoes
    • Largest
    • Hawaiian volcanoes
    • Less explosive except when water enters
    • Basalt - fluid - so not steep
  • Cinder cone
    • When lava fills the cone of shield volcano
  • Composite  volcanoes
    • Cooler than basalt
    • Explosive
    • Ashes and pyroclastic material forms layer called composite
  • Caldera
    • Most explosive - so collapse on themselves
    • Magma chamber is huge and close
  • Flood basalt Provinces
    • Highly fluid basalt
    • Deccan traps
    • 50 m thick and 100 km flow
  • Mid-oceanic Ridge Volcanoes
    • 70000km long ridges
  • Volcanic land forms
    • Intrusive forms - cools within crust
Image result for intrusive forms
  • Cooling of lava - ingenious rock
    • Cools on surface - volcanic rocks
    • Cools in crust - plutonic rocks
  • Plutonic rocks
    • Batholiths
      • Large
      • Deep
      • Granite
    • Lacoliths
      • Large
      • Flat base
      • Connected by conduit from below
      • Karnataka plateau granite
    • Lapolith
      • Saucer shape
      • Concave to sky
    • Phacoliths
      • Wavy rocks at syncline or anticline
    • Sill or sheet
      • Near horizontal
      • Thick - sills
      • Thin - sheet
    • Dykes
      • Vertically solidifies as the lawa rise
      • Feeder for MH deccan trap

4.DISTRIBUTION OF OCEANS AND CONTINENTS

  • 71% of earth oceans
  • Continental drift theory 1912
    • Alfred Wegener
    • PANGAEA means all earth
    • PANTHALASSA means all water
    • PANGAEA into LAURASIA and GONDWANALAND
  • Evidence in support of the continental Drift
    • The matching of continents (jig-saw-fit)
    • Rocks of same age across the oceans
    • Tillite - a sedimentary rock formed out of deposits if glacier - seen across continents
    • Placer deposits
      • Gold deposit in Ghana coast
      • Gold bearing veins in Brazil
    • Distribution of fossil
      • Lemurs in india, madagascar and africa
      • Mesosaurus in south africa and brazil
    • Forces for drifting - but false
      • Polar-fleeing force due to rotation of earth
      • Tidal force
  • Post drift studies
    • Convectional current theory
      • 1930 - Arthur Holmes
      • Convectional current due to radioactive elements causing thermal differences in mantle
    • Mapping of ocean floor
      • Similarities in magnetism of rocks equidistant from ridges
      • Presence of ridges along continental margins
    • Ocean floor configuration
      • Continental margins
        • Transition between continental shores and deep-sea basins
        • Includes continental shelf, slope, rise and deep oceanic trenches
      • Abyssal Plains
        • Between continental margins and mid-oceanic ridges
      • Mid-Oceanic Ridges
    • Concept of sea floor spreading by HESS
Convergent 
Plate Boundary 
Strato 
Vole•arui• 
Transform 
Plate Boundary 
Volcano 
Hotspot 
Convergent 
Plate Boundary 
Divergent 
Plate Boundary 
Trench 
Ridk't• 
Continental Rift Zone 
(Youn plate boundary) 
• Coriinental Crust 
Lithosphere 
Oceanic crust 
S.ubducting 
• Plate 
Figure 4. 3 . 
• Sea moor spreading
  • Plate Tectonics
    • Convectional theory + sea floor spreading
    • Continental or oceanic
    • Crust + upper mantle
    • 7 major and 7 minor
      • Major - Antarctica, North America, South America, Pacific plate, India-Australia-new zealand plate, Africa, Eurasia
      • Minor - Cocos, Nazca, Arabian, Philippine, caroline, fuji
  • Types of plate boundaries
    • Divergent Boundaries - new crust - mid-oceanic ridge
    • Convergent Boundaries - subduction zone
      • Oceanic - continental plate
      • Oceanic -Oceanic plate
      • Continental - continental
    • Transform Boundaries
      • Crust neither destroyed or produced
  • Rate of plate movement
    • Arctic ridge 2.5cm/yr
    • East pacific Rise near Easter Island 15cm/yr
  • Force for the plate movement
    • Due to radioactive decay and residual heat convection cell beneath solid plate
    • Arthurs Holmes said 1st
  • Movement of Indian plate
    • 200 million year ago started
    • 40-50 million year ago collided

5.MINERAL AND ROCKS

  • 98% crust is oxygen, silicon, aluminium, iron, calcium, sodium, potassium and magnesium - in same order
  • Hardness
    1. 1.Talc
    2. 2.Gypsum
    3. 3.Calcite
    4. 4.Fluorite
    5. 5.apatite
    6. 6.feldspar - half the earth/ceramic and glass making
    7. 7.quartz - part of granite/radar and radio
    8. 8.topaz
    9. 9.Corundum
    10. 10.diamond
  • Other minerals
    • Pyroxene - 10% of crust/meteorites
    • Amphibole - 7%/asbestos
    • Mica - electrical instrument
    • Olivine - jewellery
  • Metallic Minerals
    • Precious metals - gold, silver, platinum
    • Ferrous metal - iorn
    • Non- ferrous - copper, lead, zinc, tin, aluminium
  • Non-Metallic Minerals
    •  sulphur, phosphates and nitrates
    • Cement is a mixture of non-metallic minerals
  • Rocks
    • Aggregate of one or more mineral
    • Feldspar and quartz are the most common mineral in rocks
    • Petrology is science of rocks
  • Types
    • Igneous - magma and lawa solidifies
    • Primary rocks
    • Outside - sudden cooling - smooth and small grains
    • Inside - slow cooling - large and big grains
    • Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff
  • Sedimentary
    • deposits through compaction - lithification
    • Mechanically formed - sand stone, conglomerate, limestone, shale, loess
    • Organically formed - geyserite, chalk, limestone, coal
    • Chemically formed - chert, limestone, halite, potash
  • Metamorphic Rocks
    • PVT
    • Recrystallisation and reorganisation
    • 2 types
      • Contact metamorphism
      • Regional metamorphism
    • Foliation or lineation
    • Banding
    • 2 types
      • Foliated
      • Non-foliated
    • Gneissoid, granite, syenite, slate, schist, marble, quartzite
  • Rock cycle

6.GEOMORPHIC PROCESSES

  • Energy through radioactivity, rotational and tidal friction and primordial heat
  • Endogenic - constructive
    • Diastrophism
      • Orogenic - mountain building through folding
      • Epeirogenic - continental building  through uplift
      • Earthquake
      • Plate tectonics
      •  
    • volcanism
  • Exogenic - destructive - wearing down or gradation by geomorphic agents and geomorphic process
    • Denudation
      • Process - weathering, mass movement, erosion/transportation
      • Driving force - gravitational/molecular stresses/chemical and kinetic
      • Weathering
        • Chemical
          • Solution - mild acids
          • Carbonation - carbonate and bicarbonate
          • Hydration
          • Oxidation and reduction
        • Physical and mechanical
          • gravitational
          • Temperature
          • Pressure

7.LANDFORMS AND THEIR EVOLUTION

  • Small to medium tracts or parcels of the earth's surface are called landforms
  • Several related landforms together makeup landscapes or large tracts of earths surface
  • 2 imp aspects of evolution of landforms - deposition and erosion
  • Geomorphic agents
    • Running water
      • Overland flow as a sheet
      • Linear flow as streams and rivers in valleys
Table of Contents hide
1 Movement of ocean water
2 biodiversity and conservation

Movement of ocean water

Movement of ocean water is influenced by

  • temperature salinity density Sun moon wind

biodiversity and conservation

Facts about species

  • total number of species is between 2 million to 10 million
  • The average of life the species is between 1 and 4 million
  • 99% of the species who have ever lived on earth have been extinct

Filed Under: Geography, GS1, NCERT

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