Many of the people who go to Florida stop on their trip to see sights, and one of the greatest sights is in Virginia and Kentucky where the rock under the ground is all limestone. The “sights” are huge caves, and in Kentucky they are so large they are called Mammoth Caves. These caves have not been dug out by men but by water. Water, you know, melts sugar; but perhaps you didn’t know that water melts rock too—not ordinary rock, but it melts limestone, and these caves are in limestone rock. The Mammoth Cave is like a huge cellar underground—a cave so large and high that you could put a whole city with its tall buildings in it. You could easily get lost and wander for miles. Men have been lost and unable to find their way out again and died and their skeletons have been found long years after.

Through the roof of the cave water drips drop by drop, and each drop leaves a bit of limestone, until in the course of time the dripping water makes icicles of rock that hang down from the roof of the cave. Drops of water from each icicle fall on to the floor of the cave, and the limestone gradually piles up and up like a stone post until at last the icicle above meets the post beneath. The trickling water also forms pools in the bottom of the cave, and in these pools of water live fish that are different from the fish in the water above ground. As it is pitch dark in the caves, these fish have no use for their eyes, so after long, long years they at last grew none. They are blind. Instead of seeing, they feel with the part of their heads where their eyes were.