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
- 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
- Direct
- 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
- P waves - fastest to arrive at surface/similar to sound wave/a.k.a primary wave/solid, liquid, gas
- Surface waves
- Body waves interact with surface rocks to form surface waves
- Most damaging
- Body waves
- 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
- Batholiths
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
- Continental margins
- Concept of sea floor spreading by HESS
- Convectional current theory
- 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.Talc
- 2.Gypsum
- 3.Calcite
- 4.Fluorite
- 5.apatite
- 6.feldspar - half the earth/ceramic and glass making
- 7.quartz - part of granite/radar and radio
- 8.topaz
- 9.Corundum
- 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
- Diastrophism
- 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
- Chemical
- Denudation
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
- Running water
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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