1915 – Germany
Continental land masses are constantly in motion. The Earth’s land surface was once one big super-continent. About 250 million years ago it broke up into the continents we know today, which have since drifted to their present positions.
Wegener proposed that the continental land masses are moving over the face of the Earth.
Rock under the ocean is principally Basalt, a denser rock than the Granite that makes up the continents. At the start of the Earth’s history there was just a single landmass, which began to break up 200 million years ago, and the parts are still moving. Mountain ranges have been produced where one moving land mass crashes into another, pushing rocks together and forcing them upwards in folds. The tectonic plates move over the asthenosphere carried by convection currents in the magma below.
Up until and beyond Wegener’s death his ideas had little scientific credence – until in the 1950s the mid-Atlantic ridge was discovered. It was this discovery that led to the concept of the tectonic plates.
- Alfred Wegener (geologyfreak.wordpress.com)
- Theory of Continental Drift (geologyfreak.wordpress.com)