ACCEPTANCE OF CONTINENTAL DRIFT

THE SITUATION CHANGED IN THE 1950’S AND 60’S DUE TO NEW DATA AND IDEAS

– MAPPING OF SEA FLOOR TOPOGRAPHY (BATHMETRY) WITH NEW SONAR (SOUND WAVES) TECHNOLOGY DEVELOPED AS A RESULT OF WWII SHOWED THAT MIDOCEAN RIDGES WERE HUGE AND EXTENSIVE FEATURES THAT WENT AROUND THE WORLD

– PALEOMAGNETIC MEASUREMENTS SHOWED THAT CONTINENTS HAD ONCE BEEN TOGETHER AND MOVED LARGE DISTANCES

– PALEOMAGNETIC STUDIES AT MIDOCEAN RIDGES SHOWED THAT OVER TIME NEW CRUST FORMED AND THEN MOVED APART

– DEEP-SEA DRILLING RECOVERED ROCK SAMPLES ALSO SHOWING THAT CRUST INCREASED WITH AGE AWAY FROM THE RIDGES

– NEW GLOBAL SEISMOGRAPHIC NETWORKS (DEVELOPED IN PART TO STUDY RUSSIAN NUCLEAR TESTS) SHOWED THAT EARTHQUAKES OCCURRED AT PLATE BOUNDARIES (MID-OCEAN RIDGES, DEEP-SEA TRENCHES, TRANSFORM FAULTS) AND SHOWED WHAT THE MOTIONS WERE

– GEOLOGICAL AND PALEONTOLOGICAL STUDIES CONFIRMED WEGENER’S ARGUMENTS THAT CONTINENTS HAD BEEN TOGETHER AND THEN MOVED

THESE OBSERVATIONS TOGETHER LED TO THE IDEA OF SEA FLOOR SPREADING AT MID-OCEAN RIDGES AND THE PRESENT THEORY OF PLATE TECTONICS