11th Standard Geography NCERT - Fundamental of Physical Geography

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

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

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

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