English: The strong pull of tidal currents sweeps water from the North Sea and the Atlantic Ocean through the narrow Strait of Dover. Resembling water-marked taffeta, the fast-moving water is streaked white, pale blue, turquoise, and royal blue in this image, taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on March 14, 2001. The water is colored by the characteristic white chalk that forms the soil of this region. The white, chalky soil reflects light, giving the water its pale color near shore. Aside from the color of the water, the chalk is evident along the shoreline, where tall, white cliffs rise on both the English and French side of the channel. On the British side, these geological formations are the famous White Cliffs of Dover. Source: http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/Dover_AST_2001073_lrg.jpg