This Dynamic Earth: The Story of Plate Tectonics

U.S. Geological Survey general-interest publication (public domain; online edition). The standard primer on plate tectonics: Wegener's Pangaea 'began to split apart' about 200 million years ago; seafloor spreading over the past 100–200 million years grew the Atlantic from an inlet; the Mid-Atlantic Ridge spreads about 2.5 cm/yr; magnetic striping records the field's reversals and yields average past rates; GPS, VLBI and SLR track present motion directly.