SEAFLOOR SPREADING

MIDOCEAN RIDGES FORM A GLOBAL SYSTEM DIVIDING THE CONTINENTS: FOR EXAMPLE

THE MIDATLANTIC RIDGE DIVIDES THE ATLANTIC, MIRRORS THE SHAPE OF THE CONTINENTS ON EITHER SIDE, AND IS TOPOGRAPHICALLY SYMMETRIC

THESE OBSERVATIONS LED HARRY HESS TO THE IDEA OF SEA FLOOR SPREADING ("AN ESSAY IN GEO-POETRY") - SEAFLOOR IS CREATED AT RIDGES BY VOLCANISM AND SPREADS OUTWARD FROM THEM