Leslie Weight, age 10, of Provo, Utah, for her question:
How are caves made?
Caves are made by dripping water. Running water, we are told, can wear away the hardest of stones. And so it can. Stones and rocks are minerals made from assorted chemicals. And many of these chemicals dissolve in water. Lime is a chemical from which little sea creatures make their shells. They perish and their shells sink to the floor of the sea where they form layers of limestone.
This limestone dissolves easily in water. Hence we find our largest and most beautiful caves in limestone hills. Rain runs down the sides of hills and some sinks into the ground. The water which sinks into the ground is the water which curves out caves,
The water sinks slowly, spending a little time in the pores of the limestone rocks. This gives it a chance to dissolve the limy chemicals from the rocks. The water is now loaded with dissolved chemicals. It is hard water and would not make the soap lather if we used it to wash.
What's more, the limestone rocks have become weakened, for some of their chemicals have been stolen. Cracks and crevices appear and fragments chip off. And all this happens deep under ground.
More rein falls and the underground cracks become wider and deeper. And still the water drip‑drips through the rocks. After hundreds of years a crack becomes a small chamber, a little cave, hidden deep in a hill. The water keeps dripping from the ceiling and, down the walls in time the cave becomes a monster cavern.
Sometimes the dripping water gathers to form an underground stream. It carves out a tunnel. The tunnel may run from one cave to another, connecting them with an underground passageway. Sometimes the water makes a puddle on the floor of the cave. In time it digs out a deep hollow and we have an underground. 1ake. And all this work is done by water lapping at the rocks, and dissolving their chemicals.
Caves are made in darkness and in secret. Nevertheless they are adorned with great beauty. The caverns are often like great cathedrals.
The stone work may look like gracefully carved drapery and mighty pillars may reach up from the floor and down from the ceiling.
This elegant stonework is also made by dripping water. The water, remember, is loaded with chemicals. In a cool cave it often evaporates, leaving its stony chemicals behind. New water‑made stone builds up bit by bit. The water dripping from the coiling builds up the stony chemicals into a stalagtite like a hanging icicle. The evaporating orator dripping to the floor piles up its chemicals into a spiky stalagmite.