Plate Tectonic Theory - Vine and Matthews (1963)

• Magnetic record of the sea floor
• Continuous recording at Ridge crests as field reverses
• Magnetic striping
• Dating of stripes
• Spreading rates; up to several cm per year, typical 1-10 cm/yr

What's moving?

• Rigid lithosphere over a soft asthenosphere
• Breakup of lithosphere into plates

Plate Geography - Seven major and several minor plates

• Plates can move Continental Crust, Oceanic Crust or both
• Neither plates nor plate margins are permanent