Continental Drift

In this video we will learn how Alfred Wegener proposed a theory in 1912 that the great continents of the Earth had drifted over geological time and were once all joined together in a giant land mass we now call Pangaea.

His idea was based on the way present day continents fit neatly together, and by the way bands of fossil-bearing rocks join up across continents. Unfortunately Wegener was unable to provide a mechanism for this movement, and his theory was ridiculed by the scientific community until 1965 when the theory of plate tectonics was published. This proposed that the continents were moved around on great plates driven by convection currents in the hot mantle of the earth. Perhaps the most dramatic evidence came from the magnetism of rocks each side of the mid ocean ridges. When rocks solidify they become weakly magnetic in the direction of the earth’s magnetic field.