Chahal's Gyan Ki Baat



  • It refers to the study of the earth's magnetic field by using magnetic fields preserved in rocks, archaeological materials, or silt etc.
  • It was first studied in the 1940s by British physicist Patrick M.S. Blackett.
  • The polarity of the Earth’s Magnetic Field and Magnetic Field Reversals can be detected by studying the rocks of different ages.
  • Basalt rocks from underwater contains magnetic minerals, these rocks align themselves in the direction of the magnetic field.
  • This keeps a record of the magnetic field positioning way at the time.
  • It also revealed that the earth’s magnetic field has reversed over time.


  • It can predict the future behaviour of Earth’s Magnetic Field as it has flipped and reversed in the past.
  • It is an important source of information about the Earth's evolution.
  • Numerous rocks have records of strength and direction of Earth’s Magnetic Field.
  • It also provides information about local and regional tectonics, geodynamics, and planet's thermal history.
  • It solved the issue of finding younger crust at the mid-oceanic ridges and older rocks as away from the ridges' centre.
  • It also explained about the thinness of the sediments in the cores of the oceanic ridges.

 How does Palaeomagnetism provide strong Evidence of Seafloor Spreading and Plate Tectonics?

  • It led to revival of continental drift theory which gave rise to Sea Floor Spreading.
  • It discovered that on the ocean ridges, alternate Magnetic rocks stripes were flipped, with one stripe of normal polarity and the other reversed.