Judith E. Linskys age 8, of Dorchester, Mass., for her question:

Are icebergs fresh or salt water?

An iceberg floating through the salty ocean is really a chunk of fresh water ice. This is true even when it comes from the sea‑washed shores of Antarctica. For all icebergs come from glaciers and glaciers are made from snow.

Countless snowfalls and tons of snow are needed to make a glacier. This mass of snow must accumulate on land, for snowflakes that fall in the ocepn soon melt or get carried away. This is why we find glaciers and icefields only on land.

In polar regions such as Greenland and the Antarctic the glaciers reach down to the ocean. Seas pound at their frozen cliffs and chunks break away. They become icebergs, floating down the ocean currents and gradually melting as they reach warmer seas.