ice shelves are principally driven by gravity-induced pressure from the grounded ice. that flow continually moves ice from the grounding line to the seaward front of the shelf. the primary mechanism of mass loss from ice shelves was thought to have been iceberg calving, in which a chunk of ice breaks off from the seaward front of the shelf. a study by nasa and university researchers, published in the june 14, 2013 issue of "science", found however that ocean waters melting the undersides of antarctic ice shelves are responsible for most of the continent's ice shelf mass loss.