Plate Formation
The theory:
New oceanic plate material wells up from the gooey mantle.
This pushes the old plates apart.
The crucial evidence:
- The new crust is (weakly) magnetized in the direction of
the Earth's magnetic field.
- Every few hundred thousand years, the polarity of the Earth's
magnetic field reverses.
- After a reversal, the new crust is magnetized the other way.
- This creates a record of the seafloor spreading.
This can be investigated by towing an instrument behind a ship. It works!
ASTR 121 Home
Davison E. Soper, Institute of Theoretical Science,
University of Oregon, Eugene OR 97403 USA
soper@bovine.uoregon.edu