Theory:

Second-order landforms
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Second-order forms
  • Mountains,
  • Plateaus and
  • Plains.
  • Mountains
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    • Mountains are landforms that are 600 meters above its surroundings.
    • Made of steep slopes
    • They are found as individual or in groups.
    • Mountain ranges extends for a large area continuously (hundreds or thousands of kilometre.
    Important!
    Peak: The highest point of a mountain.
    Examples:
    Mountain Range
    Continent
    HimalayaAsia
    Rocky MountainsNorth America
    AndesSouth America
     
    The longest mountain range in the world: The Andes (7,000 km)
    The highest peak in the world: Mt. Everest (8,848 m)
  • \(December 11 International Mountain Day\)
  • Hill Stations in Tamil Nadu: Udhagamandalam, Kodaikanal, Kolli hills, Yercaud and Yelagiri.
  • Plateaus
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    Plateaus: the elevated portions of the Earth that have flat surfaces sorrounded by steep slopes.
    • Elevation of plateaus: few hundred meters or several thousand meters
    • The highest plateau in the world: Tibetan Plateau
    • Tibetan plateau is also called as the ‘Roof of the world’.
    • The flat-topped part of the plateau is called Tableland.
    • The plateaus are generally mineral-rich in nature.
    • The Chotanagpur Plateau is one of plateaus in India, i.e. rich in minerals.
    • Mining is one of the major activities of the people living here.
    • The Deccan Plateau is an example of volcanic plateau, i.e. volcanic origin.
    Plateaus in Tamil Nadu: Dharmapuri Plateau, Coimbatore Plateau and Madurai Plateau
    Plains
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    • Flat and relatively low-lying lands.
    • Usually less than 200 meters above sea level.
    • Maybe they are rolling or undulating sometimes.
    • Most plains are formed by rivers and their tributaries and distributaries.
    • Due to fertile soil deposited by rivers, they are extensively used for agriculture.
    • Most suitable topography for human inhabitation, therefore highly populated.
    • The plains have been the cradle of civilisations from the earliest times.
    For example:
    Civilisation
    River
    Country
    IndusIndusIndia
    Nile valleyNileEgypt
    MesopotamianTigris–EuphratesWest Asia
    Important plains in Tamil Nadu: Cauvery and Vaigai.
    Important!
    Indo-Gangetic plain is one of the largest plains in the world.
    • Coastal plains: Low lying lands adjacent to oceans and seas
    Third-order landforms
    • These landforms are formed as a result of erosional and depositional activities of rivers, glaciers, winds, and waves on mountains, plateaus, and plains.
    • Example: Valleys, beaches and sand dunes
    Valley
    Beach
    Sand dunes
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    • The process of removal of surface material from the Earth's crust is known as erosion.
    • The transportation and deposition of eroded materials on the low lying areas is known as deposition.