Charles scholl, age 12, of pewaukee, wisc., for his question:
What are ice caves?
Most of us have been inside a system of rocky caves and caverns and seen the wonders of dripping stalgtites and spiky stalagmites. These natural works of art are beautiful to behold, but they are made of mere stone. Imagine this art work carved from glittering, glassy ice.
Some ice caves are carved by the pounding waves of the sea, and some are formed by the changing weather above a glacier. All glaciers are made from frozen snow, pressed until it is as hard and solid as many of the earthts rocks. In Greenland, glaciers form on the peaks and shoulders of the mountains, and through the years they slide slowly down the slopes into the valleys. The south polar region is covered by a thick ice field that spreads outward from the center to meet the icy waters of the seas.
Ice, of course, is frozen water, and geologists rate it as a mineral. As a mineral, however, it is weak and brittle. It can be chipped and broken by the waves of the ocean, and around Antarctica the rough ocean chews great holes into the cliffs of ice that face the shores. These holes in the glacier are ice caves and giant caverns.
Glacial ice tends to split and crack under its own weight, forming deep clefts and crevasses. In Greenland, the summer thaws melt the surface ice and warmish water seeps and trickles down the crevasses into the icy heart of the glaciers. This water melts the icy walls it touches, dissolving them bit by bit. Sometimes a stream cuts out an icy tunnel at the bottom of the glacier and flows on to escape into the open as a glacial stream. Sometimes it dissolves a honeycomb of caves and caverns deep inside the glacier.
Time after time the invading water within the glacier freezes to solid ice and thaws again. It drips from the ceiling of the caves and drops drip by icy drip upon the floors. It forms icicles like the stalactites and stalagmites that adorn the ceilings and floors of limestone caves and caverns. The thawing and freezing water decorates the walls of ice caves with rippling scrolls and other designs. And all this elaborate art work is made of ice glassy, glittering ice that reflects and refracts the light in millions of dancing sparkles.
Most of the earth's rocky caves are carved in limestone, and the work is done by the drip drip of ground water as it seeps and trickles through cracks and crevices. Its thirsty tongues lap at the limestone, dissolving its soft minerals. The water evaporates in the cool caves, leaving its load of stony minerals behind to form new formations. The art work of a sparkling ice cave is done by chilly water as it freezes into spikes and other shapes of solid ice.