These “ice streams” can be up to 30 miles wide, over a mile deep and are actually a kind of glacier. They are prominent features across the frozen continent where they comprise 10 percent of the volume of ice.

The streams can flow a distance of more than a half-mile each year, which is several times faster than the surrounding ice.

The European Space Agency’s Envisat satellite captured the tinted image to the right of one such ice stream on March 23, 2009.

Due to sunlight restrictions so far south and the lesser resolution of other instruments, the image was captured using the ASAR radar sensor orbiting aboard Envisat. It has enough resolution to see objects about 100 feet across, and can map terrain in far greater detail than sensors using visible light or infrared.

In the image, two branches of one ice stream can be seen flowing from the bottom within the field of view toward top and left.

Most ice streams have some water at their bases, which lubricates the flow. The type of bedrock beneath the ice is also an influence. Soft, deformable sediments result in a faster flow than hard rock.

It has been suggested that the entire Antarctic ice sheet is losing mass. The increase in flow of ice streams and outlet glaciers may be the main cause of this trend.

Image: European Space Agency