Continental Drift

• Professional geologists didn’t believe it till ‘60’s
  • seafloor spreading discovered
• drift rate 1000 km / 65 My ~ 2 cm/y
  • This is the average rate -- what is the rate right now?
    • With the Global Positioning System, can measure the velocity in about 3 y
      • Pacific plate is colliding with S. America (creating Andes) at a rate of ~ 3 cm/y
      • GPS is amazing!

• Earth’s magnetic field

  • ~ 1 gauss at surface
    • cf. refrigerator magnet ~ 1000 gauss
  • bar-magnet “dipole field” Z51
    • recall demo for Sun’s magnetic field
  • North pole in Greenland Z50
  • Dipole field distorted by solar wind TA60

Previous slide

Back to first slide

View graphic version