Mammoth Cave's miles of hollow halls were already thousands of years old when the first human beings came on the scene, and the Cave stands as a natural wonder in its own right.  But grandeur and fascination, awe and wonder, fear and courage, trepidation and daring – those feelings that have given the Cave its power to inspire millions – are a human contribution.

Stalactites grow downward – they hang "tight" to the ceiling – while stalagmites grow upward – they "might" reach the ceiling someday. Mammoth Cave's formations include many types of calcite formations.

Green River