Our Changing Earth

• Lithospheric Plates

  • Definition: Broken pieces of the Earth's crust
  • Movement: Slow movement due to magma inside the earth
  • Force Classification
    • Endogenic Forces (Internal forces)
    • Exogenic Forces (External forces)

• Endogenic Forces

  • Sudden Forces
    • Earthquake
      • Focus: Origin point inside the earth
      • Epicentre: Point on surface above the focus
      • Seismic waves spread outwards
      • Measurement: Richter scale (0 to 9)
      • Protection: Safe spots, drop-cover-hold
    • Volcano
      • Vent in the crust
      • Eruption of molten magma
  • Slow Forces
    • Mountain building processes

• Exogenic Forces

  • Processes
    • Weathering: Breaking up of rocks on Earth's surface
    • Erosion: Wearing away of landscape by agents like water, wind, and ice
    • Deposition: Accumulation of eroded material
  • Work of a River
    • Waterfall: Formed by hard rocks dropping water vertically
    • Meanders: Large bends formed as the river enters plains
    • Oxbow lake: Cut-off meander loop
    • Flood plains: Low-lying flat areas formed by river deposits
    • Leveis: Raised banks along the river
    • Delta: Triangular collection of sediments at river mouth
  • Work of Sea Waves
    • Sea caves: Hollowed-out caves in rocks
    • Sea arches: Arched cavities when caves become bigger
    • Stack: Pillar-like remaining structure after roof collapses
    • Sea cliff: Steep rocky coast rising almost vertically
    • Beach: Shores covered with sand and sediments
  • Work of Ice (Glaciers)
    • Glaciers: Rivers of ice
    • Moraines: Glacial deposits (rock big and small, sand, silt)
    • Glacial lakes: Formed in mountains when ice melts
  • Work of Wind
    • Active in Deserts
    • Mushroom rocks: Rocks shaped like a mushroom (narrow base, wide top)
    • Sand dunes: Low hill-like structures of sand
    • Loess: Fine, deposited grains of sand spread over large areas