Notes on INDIAN GEOGRAPHY for Prelims INDIAN GEOGRAPHY Cosmology: Science dealing with the nature and origin of the universe. Big Bang Theory: Canon Lemaitre Steady State Theory: Hermann Bond and Thomas Gold. Pulsating universe theory: Allan Sandage. One Parsec = 3.26 light years. Hydrais the largest constellation. When brightness of a star increases 20 magnitudes or more, it is called a supernova. Sun accounts for 99.85% of the mass of the solar system. Suns Revolutionary period= 250 m years Rotation time = 25 days Planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune Venus and Uranus rotate anti- clockwise at their axis, whereas all other planets rotate clockwise. Largest Terrestrial Planet:- Earth Smallest Jovian Planet:- Neptune Mercury and Venus have no satellites. Jupiter has the largest rotational velocity. Genemedeof Jupiter :- Largest Satellite Titanis the only satellite in the solar system with an atmosphere of its own. Saturn has the least density among all the planets. Uranus is also known asGreen planet. Greatest satellite of Neptune : Triton Movement of the Earth. 1)Rotation: West to east in 24 hours (produces day and night) – Line separating light and dark halves is known as thecircle of illumination. 2)Revolution:Movement around the sun 365 ¼ days (produces seasons) – Jan 2 : Closest to the sun- calledPerihelion. July 4 : Farthest from the sun- calledApehelion. 3)Eccentricity: (Produces Ice-age and Global Warming) Shape of the earth’s orbit changes in a cyclic period running between 90,000- 1,00,000 years. 4)Precession: This is the conical motion of the axis of the spinning earth, like a spinning top. Takes about 26,000 years to complete one cycle. Presently – pointing atPole star. AD 4000- pointing atAlpha cephai A D 14,000 – pointing atStar vega Summer Solistice: 21st June: Sun overhead at tropic of cancer. Winter Solistice: 22nd Dec : Sun overhead at the tropic of Capricorn. Vernal Equinox: 21st March. Autumn Equiox: 23rd Sep Our moon is 1/4th of the size of Earth. Blue Moonis said to occur when the second full moon appears within the same month. Highest Mountain on Moon:Liebnitz: 10,660m Neil ArmstrongandEdwin Aldrin: Set foot on theocean of Tranquility In a calendar year, a maximum of seven eclipses can occur( combining solar and lunar eclipses) Remember 1 degree latitude or longitude represents 111 Km ( along equtor) Longitude and Time Rem: E-G-A [ East- gain- add] W-L-S[ West- lose- subtract] Earth moves 1 degree in 4 minutes. Standard meridians differ from Greenwich Meridian by the multiples of 15degree or 7.5degree. USA and Canada have 5 time zones. India has one time zone. -82.5 degree east from the Standard time - 5 hours and 30 minutes ahead of GMT The International Date Line: - 180 degree Meridian is the international date line. - A traveler crossing this date line from east to west will lose a day. - A traveler going from west to east will gain a day Latitudes 1. Earth Moves 1 deg in 4 minutes. 2. Standard meridians differ from Greenwich Meridian by the multiples of 15 deg or 7.5 deg. 3. USA and Canada have 5 time zones 4. India has one time zone a. 82.5 deg E from the standard time b. 5 hours and 30 minutes ahead of GMT The International Date Line 1. 180 deg meridian is the international date line 2. A traveller crossing this date line from east to west will lose a day. 3. A traveller going from west to east will gain a day. Construction of Earth's Interior 1. Relative Density= 5.5 2. Seismic Waves a. p-waves or primary waves: Also called longitudinal or compressional waves- like sound waves- fastest b. Secondary waves or S-waves:Also called transverse or distortional waves- like water ripples- cannot pass through liquid material. c. Surface Waves or L waves:Long wave length waves- cause most destruction. Earth's Surface 1. The Crust: It has two layers: Sial and Sima. These two layers extend to a distance of 30-40 km from the earth's surface. The join of Crust and Mantle is calledMohorovicDiscontinuity. 2. The Mantle:It extends from 35-2900 km. The join of Mantle and Core is called the Gutenberg Discontinuity. 3. The Core:It extends from 2900-5150. It is also called NiFe because of the presence of Nikel and Iron. Mechanical Division of Mantle 1. Lithosphere:It constitutes 80-100 km of upper most mantle. It is rigid and cool 2. Asthenosphere:It is also a part of the upper mantle. It is hot, soft and pliable. Remember:All the meridians and only the equator form great circles. Composition of Earth 1.Crust Composition:Oxygen: 46.8%, Silicon: 27.7% 2. Total Earth Composition: Iron: 35%, Oxygen: 30%, Silicon: 15% Continental Drift Theory 1. According toAlfred Wegnerabout 250m years ago, all continents were united on a super continent called asPangaea, which was surrounded by a large ocean calledPanthalsa. 2. Continents Drifted in Two Directions: a.Towards Equator:Due to Gravitational attraction of equatorial bulge ( caused the formation of Himalayas, Alps, and Atlas) b.Towards West: Owing to tidal forces of moon and sun ( Caused the formation of Rockies and Andes) Rocks, Earthquakes and Volcanism 1. About 90% of rock forming minerals are silicates. 2. Felsparis the most abundant rock forming silicate material. 3. About 75% of the surface area of the globe is covered by the sedimentary rocks while rest 25% area is occupied by the igneous and metamorphic rocks. 4. Shaleis the most abundant sedimentary rock. 5. Marble is a metamorphic rock from limestone, Diamond from Carbon etc. 6. Richter Scaleis used to assess the magnitude of an earthquake. It is logarithmic, it means each whole no on the scale represents a ten fold increase in the measured wave amplitude. It is a quantitative scale. 7. Intensity of earthquake is measured byMercalli Scale. It is a qualitative scale. Earth's Movements 1. Faults: Here the rock beds are dislocated and displaced resulting in the formation of faults. 2. Rift Valley:Is a linear depression on earth eg. Narmada and Tapti. Dead sea, the most saline lake after lake Van are situated in a rift valley. 3. 66% of the earthquakes of the world are recorded in Circum-Pacific Zone. 4. With the increasing depth, the temperature rises gradually at 1 deg C per 32 m. 5. Molten rock material below Earth's surface is called Magma, above Earth's surface is called Lava.