Under the massive forces of their own weight, the ice sheets deform and drag themselves outward. Very large glaciers called ice streams flow through them continually, transporting ice from the center of the continent to the sea. When ice streams finally reach the coast and push out across the ocean, they pass over rocky terrain, anchoring themselves to the irregular rocks to form a hinge. The ice will continue to grow outward onto the water. The result is a large, floating shelf of ice affixed to the continent.
Ice shelves cover fifty percent of the Antarctic coast.
The surface area of all ice shelves taken together is more than one tenth the size of the continent. The largest individual shelf is the Ross Ice Shelf in West Antarctica, also called the Great Ice Barrier. It is as big as France and fed by no less than seven ice streams. Ice shelves actually float up and down with the tides, grating against the rocks and eventually breaking apart. In fact, the tides will eventually destroy an entire shelf.