Touring the Inside of a Glacier

It is unlikely that the best of mankind's crystal palaces can ever equal the beauty and mystery of the ice caves which nature creates at leisure in its own glaciers. A glacial ice cave can be an explorer's dream. But changing constantly, it can also be a deadly hazard.

Glacial ice is created when several seasons of accumulated snowfall compact the underlying layers to a fraction of their former volume. The delicate snow crystals are packed more tightly, resulting in "fire" snow. Fire can last through at least one more warm season even if the snow above melts, and eventually the crystals interlock to form bigger and bigger chunks, squeezing out the remaining air bubbles. At a density of 0.84 gram per cubic centimeter (water weighs 1.0 gram per cubic centimeter), the transition from snow to glacial ice is complete.

The glacier now takes on a beautiful blue appearance, because sunlight passing through the ice has had the red end of the spectrum filtered out. The same thing happens in the ocean when everything below a depth of about 200 feet (including blood) appears blue. Ice does the job more quickly and at a shallower depth.

The next step in the creation of an ice cave begins when meltwater trickles down through cracks and fissures on the surface, forming small streambeds on the ground below. These small streams grow in size and carve openings as they emerge from beneath the glacier. Through these openings, air begins to circulate when the water is low, and melts more ice on the walls and ceilings of the cave. Slowly, a network of caverns and tunnels is established, complete with a fairyland of ice crystals growing on exposed surfaces which assume strange and unworldly shapes in the eerie blue light.

Because glaciers are living and moving things, the caverns do not retain their shapes for long, and a visitor never sees the same cave twice. This is what makes ice cave exploration extremely dangerous as well as exhilarating. Doug Buchanan, one of Alaska's premier ice cave spelunkers, reports that a glacier groans, creaks and pops on the inside. A sobering thought is that you're never sure when one of the pops might be a warning that tons of ice are about to give you a severe and permanent headache.