The two directories here contain:

1) The suggestion and then observational verification of sea floor
   spreading via observations of symmetric magnetic reversals on the
   two sides of ocean ridges. Several possible tracks into this subject:

   a) Vine 1966: wikipedia entry on plate tectonics: 1st page, "key points" p 3-4, map of plates p 11, plate tectonics theory+Explanation of magnetic striping+Subduction discovered p 13-14; then Vine (1966).

   b) Hess paper: ...

2) Theoretical work analyzing plate motion/ plate motion on a sphere,
   compared with continental motion observations and showing that
   continents indeed move as if they are part of large rigid plates