Norman Burstein, age 10, of Drexel Hill, Pennsylvania, for his question:

How big is the Ross Shelf?

This amazing slab of ice varies from 150 to 1,000 feet in thickness and its area is almost large enough to cover the entire country of France. This size, of course, is a mere button when compared to other glaciers of the Antarctic South. Polar Regions. But these glaciers, or most of them, rest securely on solid ground. The Ross Shelf does not. It is a giant slab of ice resting on nothing but the water of the Antarctic seas. Actually, it is pushed out to sea by the spreading glaciers behind it.

The Ross Sea and the Weddell Sea bit two large bays into the land, leaving a slim wasp waist on the western side of Antarctica. For a long time, no one suspected that a large portion of each bay was covered with a shelf of ice. This sea going ice seemed to be resting on the land. The larger Ross ice shelf pushed forward 500 miles from land along a front 400 miles wide. From time to time, the pounding waves bash off great chunks of the shelf. The fragments float out to sea as flat topped icebergs, some of them 50 to 100 miles long.