DIVERGENT PLATE BOUNDARIES

CONTINENTS SPLIT BY STRETCHING AND RIFTING

IN SOME CASES RIFT DIES (“FAILS”); IN OTHERS RIFT EVOLVES TO OCEANIC SPREADING CENTER WHERE NEW CRUST FORMS BY MAGMATISM, WIDENING OCEAN BASIN

(Press & Siever)

OCEANIC RIDGES STUDIED WITH MARINE GEOLOGY AND GEOPHYSICS, AND FROM OCEANIC CRUST THAT IS SOMETIMES EXPOSED ON LAND (OPHIOLITES)

HYDOTHERMAL INTERACTION OF SEA WATER WITH HOT ROCK MAKES SPECTACULAR HOT SPRINGS AND HAS MAJOR EFFECT ON OCEAN CHEMISTRY

OCEANIC LITHOSPHERE COOLS AND THICKENS AS IT MOVES AWAY FROM THE RIDGE, MAKING OCEAN DEPTH INCREASE, AND PROVIDING ONE OF THE FORCES DRIVING PLATE MOTIONS