sea-floor spreading

Noun

seafloor spreading (usually uncountable, plural seafloor spreadings)

1. (usually) The outward movement of the seafloor from central underwater ridges as a result of plate tectonics; the major cause of continental drift.
   • However, the recognition of sea-floor spreading made sense of continental splitting without having to invoke earth expansion.2004, Richard Fortey, The Earth, Folio Society, published 2011, page 143