Near the lava flows of Grants, New Mexico (USA) is an ice-walled cave. The ice is a
source of water and refreshment, as well as a wonder to tourists. Ice forms a solid
wall, five feet high and forty feet across, that fills a cavity in a cave that once held
hot lava. When the lava cooled, it trapped air bubbles that now function as insulators.
The ice is tinted blue-green by airborne pollen, and formed when the region was much
colder. The wall is also striped with dust that settled on succeeding layers of freezing
water. Even though the temperature outside the ice wall can be scorchingly hot, the ice
stays cold and melts only enough to make a trickle of water. Winter rains and snow
replenish any melting ice, though the wall is slowly shrinking.