Diagram of the Earth during the Carboniferous period, 1922. Land is represented by the unshaded areas, deep sea by the areas shaded with diagonal lines and shallow water with horizontal lines. From an article by Alfred Wegener (1880-1930) on his theory of Continental Drift published in Discovery, London, 1922. Wegener postulated that the continents had not always occupied their present locations, but had moved across the Earth's surface over geological history. Wegener's theory was not widely accepted until the 1950s, but is today explained by the theory of Plate Tectonics.