Just as the Amazon, the Mississippi, the Zambezi, the Yangtze, and Earth's other mighty rivers drain the continents, rivers also drain Antarctica, only in this frozen landscape, the rivers are ice. Under their own massive weight, the Antarctic Ice Sheets are constantly spreading out like a mound of batter on a griddle. The outer edges of the ice sheets crumble into the Southern Ocean as they spread, giving birth to icebergs. In some places, steep mountains channel the flowing ice sheet into fast-moving rivers of ice. The Byrd Glacier is one such place. Located near McMurdo Station, the principal U.S. Antarctic Research Base, the Byrd Glacier plunges through a deep, 15-mile-wide valley in the Transatlantic Mountains to create a 100-mile-long, rock-floored ice stream. This image, captured by the Landsat 7 satellite on December 24, 1999, shows part of the Byrd Glacier flowing through the Transatlantic Mountains. The glacial ice has a blue cast, and bears long stripes that echo the currents in a river. The current in this ice stream carries the glacier towards the Ross Ice Shelf at a rate of one half mile per year. Though this may seem like a snail's pace, the Byrd Glacier is fast-flowing. It contributes more ice to the Ross Ice Shelf than any other ice stream, and the long grooves that mark its outflow are visible all the way to the edge of the Ross Ice Sheet, some 270 miles from the foot of the mountains.