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Ready for another riddle? What can be as small as a telephone
booth or as big as a mountain? This time the answer is easy:
A cave.
Not every natural opening in the ground is a cave. It must be
big enough to hold a person.
Many caves form in limestone. First, water seeps into cracks
between its layers. Then chemicals in the water slowly eat away
at the sedimentary rock. As time passes, the cracks grow wider
and deeper. Eventually, large tunnels and rooms form. Years
later, the water drains out and the cave fills with air.
Sometimes icicle-shaped
stalactites
grow down from the
ceiling of a cave. Stubby
stalagmites
may grow up from the floor.
They make caves beautiful places to visit.
A Peek Inside
Caves
