The underground wonderland of spectacular Mammoth Cave was formed, and is still being formed, as limestone, also called calcium carbonate, dissolves in water seeping through the ground.
This phenomenon is usually found where caves occur. Underneath the topsoil on the hills of southern Kentucky, there are two layers of stone. The upper is a sandstone cap that is 50 feet thick in some places. Like an umbrella, it covers the lower layer, a series of limestone ridges.
At places called sinkholes, surface water is able to penetrate the upper sandstone umbrella. As the water works its way downward, the limestone is eroded, forming the honeycomb of underground passageways, amphitheaters, and rooms that make up Mammoth Cave.
Many of the cave's internal features, such as stalagmites, stalactites, and columns, were formed this way. These formations build at the rate of about one cubic inch every 100 to 200 years.
Mammoth Cave History: Inhabitants and Exploration
People have been crawling through and living in the cave since prehistoric times. Anthropologists believe that Native Americans first discovered the great cave about 4,000 years ago. To light their way in the intense underground darkness, they fashioned torches from bundles of cane like that which still grows nearby. Charred remnants of these ancient torches have been found miles inside the cave in chambers lined with thousands upon thousands of gypsum crystals in myriad shapes. Apparently, these crystals were highly valued by the early spelunkers.
The cave also holds ancient footprints, undisturbed for centuries, as well as bits of clothing and abandoned sandals. Three miles from the cave entrance, the mummified body of a gypsum miner who died some 2,000 years ago has been discovered. He was crushed to death by a five-ton boulder. The man's body and his clothing are perfectly preserved.
Mammoth Cave was first discovered by white pioneers in the late 1790s, and guides have been leading astonished tourists through it ever since. During the War of 1812, the cave was mined near its entrance. Slaves did most of the work, filling large leaching vats with dirt and rock from the cave. The potassium or calcium nitrate crystals produced by this operation -- also called saltpeter -- were used to make gunpowder.
One of the earliest guides, Stephen Bishop, aptly described the cave as "grand, gloomy, and peculiar." He was a slave of the man who bought the cave in the 1830s, hoping to develop it as a major tourist attraction. Bishop explored and mapped many of the cave's rooms and passages. His assessment of the cave is almost as accurate today as it was 160 years ago. Park officials still do not overlight the cave's interior, guaranteeing that visitors never lose the feeling that they are deep within the earth.
Visiting Mammoth Cave National Park is a once-in-a-lifetime experience. The geology of this great cave has inspired awe in people for thousands of years.
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