Continental drift Continental drift Continental drift is the theory that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by many for lack of any motive mechanism. Arthur Holmes later proposed mantle convection for that mechanism. The idea of continental drift has since been subsumed by the theory of plate tectonics, which explains that the continents
Drift ice Drift ice Drift ice, also called brash ice, is any sea ice other than fast ice, the latter being attached ("fastened") to the shoreline or other fixed objects (shoals, grounded icebergs, etc.). Drift ice is carried along by winds and sea currents, hence its name. When drift ice is driven together into a large single mass (>70% coverage), it is called pack ice. Wind and currents can pile up that ice to form ridges up to several metres in height. These represent a challenge for icebreakers and offshore structures operating in cold oceans and seas. Drift ice consists of ice