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Millions of years ago, Kentucky was covered by a sea. Deposites of animals and plants settled to the bottom of the sea forming thick layers of limestone. After millions of years, rainwater mixed with carbon dioxide formed an acid which slowly worked its way into cracks dissolving the limestone. This water flowed underground carving out large caverns. South-central Kentucky is the home of the longest caves in the world.
Karst
Karst is a term which describes cave country. It includes what is above and below ground. Karst areas allow groundwater to move for long distances underground without being filtered. Karst includes caves, sinnkholes, springs and underground rivers. The water in Kentucky's caves can easily be polluted by sewage. Illegal dumping in sinkholes, uncontrolled soil erosion, chemical spills, and agricultural run off, all contribute to the pollution of the water. This can be a major problem in that cities often get their drinking water from underground streams.
Mammoth Cave
Mammoth Cave is the longest surveyed cave in the world. People have explored over 365 miles of passages. It lies beneath a protective layer of sandstone. The cave is dry most of the time because sandstone shields the cave from water. Carbonic acid in the water dissolved the limestone. Over millions of year this process has created large caverns under the Earth's surface. The cave has several networks of caves located under five different ridges at five different depths. Mammoth Cave was also used by Indians and miners. The Native Americans burned reed torches for light when they explore the cave.
Hidden River Cave
Hidden River Cave is located in the town of Horse Cave. The entrance of the cave is very large with many passages connected by a subterranean river called Hidden River. The cave was closed to tours for 50 years due to groundwater pollution. People didn?t understand that when they let their sewage flow into the ground that it went directly into the cave. Water drains into the cave very quickly because it doesn?t have a sandstone cap that covers the cave. People have explored Hidden River Cave for more than seven miles.
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