Frequently Asked Questions

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NPS Photo/ Nathaniel Leies

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Why is it called Mammoth Cave?

Many wonder if Mammoth earned its name by the discovery of an ancient prehistoric pachyderm. This place earned the name Mammoth because of the grandeur showcased by the size of the chambers, not for the Wooly Mammoth. The Rotunda boasts ¼ acre room. Early visitors did not get the opportunity to experience rooms this large. When they would write about their experiences they would often refer to the cave system as mammoth. After a while, that became the name everyone recognized, The Mammoth Cave of Kentucky. 

 

Why are there no cave formations?  

Mammoth Cave is considered a dry cave. Above all the layers of limestone rock there are two more layers of sedimentary rock, sandstone and shale. These layers of rock were created long after the development of the limestone. A river flowed over this area leaving behind sand, silt and mud. These deposits solidified to form the sandstone caprock of Mammoth Cave. Unlike the soluble limestone, water can not penetrate through this type of rock. The insoluble rock layers keep Mammoth Cave dry. It is this feature that allows Mammoth Cave to be world’s longest cave system and allows all the artifacts in the cave to be preserved. 

There are a few places where that caprock is weakened or absent and water can slowly make its way through the layers. In this locations we do find the classic cave formations such as; stalactites, stalagmites, draperies, soda straws, cave bacon, cave grapes, cave popcorn and rim stone dams to name a few. All of these formations are typical of a wet cave.  

Tours to see wet formations: Frozen Niagara, Domes and Dripstones, Gothic Avenue, Violet City [lantern tour], Grand Avenue, Great Onyx [lantern tour], Introduction to Caving [crawling tour], Wild Cave [crawling tour].
 

How often do rocks fall?  

Only Once, lol. Typical cave humor. It’s the lowest form of humor there is, lol... 

Enough with the horrible puns. This is a legit question that comes up quite often. The truth of the matter is that it does occur occasionally. These stone passages stabilized themselves long ago and there aren’t many outside forces acting on them. Sometimes there are changes in the environment that affect the rock layers. Areas next to entrances or ventilation shafts experience sufficient temperature change to create ice wedging between the layers. In areas where water is still flowing freely the cave experiences changes as rocks are dislodged by the water. 

Are people still exploring the cave?  

Cave exploration is still active and headed up by the Cave Research Foundation. The group is comprised of scientists, cave enthusiasts and members of the National Speleological Society.  The Cave Research Foundation (CRF) expedition leaders schedule excursions into the cave on holiday weekends when the members are off from their everyday jobs. Pushing their limits down in these depths trying to find those unexplored passages to add to length of this system. 
 

How much of the cave was enlarged by people? 

Mammoth Cave is what is considered a solution cave. Which means it was formed in soluble rock through a chemical reaction that caused the rock to dissolve thus creating passages. The cave is naturally formed by the underground rivers flowing against the limestone walls. The cave walls and ceiling have not been altered by man. The rivers that flowed through left behind large amounts of sediment and displaced rocks.  

Throughout the use of the cave the floor has been altered. That is to say, loose rocks have been moved around and dirt has been removed in some areas to allow for more clearance between the floor and ceiling. In the Rotunda, the floor has been built up by the saltpetre processing. After the nitrates were removed from the sediment, mine workers would shovel the wet mud from the leeching vats. The spent dirt was piled up along the sides of the chamber. This caused the floor of the room to rise almost eight feet in some places.
 

How many entrances are there?  

So far, we know of 27 entrances. The Historic Entrance is the largest natural entrance. A total of six entrances are used by visitors to access different guided tour experiences. The Great Onyx entrance is not counted among those because the connection of these two cave systems has not been found yet.  

 

Is there gold or gems in the cave?  

No. The limestone rock is not ideal for discovering gold or other gems. However, aside from calcite formations, the cave does have a variety of minerals that can be found on its walls. Salts such as gypsum, epsomite, and mirabilite can be found within the cave. Some of these were harvested by prehistoric Native Americans.

 

What is the black stuff on the walls? 

As the limestone is drying out pushing moisture from its pores, it is picking up other minerals along the way. Here, when the moisture evaporates from the surface of the rock it leaves behind gypsum. The build up can take on various forms depending on the shape of the pore it traveled through. Through small pores a sugary crust will develop along the surface. It sparkles like fresh fallen snow. Naturally it is white in color but also appears light brown due to interactions with impurities found here. If the gypsum is forced from a larger pore, sugary lilies and clusters of delicate flowers will bloom on the walls and ceilings. These fragile formations are rated a two on the Mohs hardiness scale (Diamond being a 10 and talc being a one). They are about the same sturdiness of dried up cake icing. In early tourism visitors were allowed to pluck these beauties from the walls to take as souvenirs. With the creation of this national park, beautiful places like this are now protected for future generations. 

In this section of the cave, the thin crust has been blackened by the smoke of bonfires and from lanterns. Native Americans harvested gypsum in the main cave. 

Tours to see dry formations: Great Onyx [lantern tour], Cleveland Avenue, Accessible, Grand Avenue, Violet City [lantern tour], Wild Cave [crawling tour], Introduction to Caving [crawling tour].

 

Why is the ceiling flat? 

Limestone is naturally formed in layers, like the layers of a cake. The limestone in the Mammoth Cave area was created when there was a salty sea covering this area of Kentucky. In this sea was a vast ecosystem of aquatic life. Many of these creatures had hard parts, such as shells. When one of these organisms died, the hard parts accumulated as sediment on the sea floor. This sediment continued to build over time and eventually solidify creating fossil rich limestone rocks. When you gaze at the expanse of a flat ceiling in the cave, you are essentially looking at the bottom surface of an exposed layer of limestone. 

 

Where is the water that formed the cave now? 

Over thousands of years the Green River has been cutting deeper into the valley. At the same time water in the cave is striving to be at the same level as the river on the outside. As time passes water is finding cracks in the limestone and seeping deeper creating layers of twisting passages. 

Once you leave the cave, you can hike the River Styx Spring trail 0.4 miles from the Historic Entrance to the Green River. This is one of many locations where the water is leaving the cave system and joining with the Green River. That will be deepest point of the subterranean labyrinth. 

 

Do earthquakes effect the cave? 

The closest major fault is the New Madrid, located almost 200 miles away. Seismic activity in South Central Kentucky does not occur often, but on the occasion shock waves may reach this area. The areas most impacted by the tremors will be on the surface. To understand this, imagine a rock being thrown into a pond. A duck swimming on top would feel the ripple and waves on the surface of the pond, but a fish swimming at some depth beneath would not be as aware. So while earthquakes can and have caused some impact in the cave, it is relatively a safer environment when compared to the tremendous impacts earthquakes can have on the surface. 
 

Where are the bats?  

The bat population has taken a very hard hit with the introduction of White Nose Syndrome and urban development. Bats have been losing much of their natural habitats. This causes them to be found in places they shouldn’t be, such as attic spaces. Food sources are also diminishing due to the increased use of pesticides. Many bat species are now considered endangered or threatened. 

Throughout the year the are about 13 different species of bats that will take up residence in this area of Kentucky. Not all of the bats will come into the cave. During the warmer season many bats opt to sleep in the hollow of trees or the thick canopy. When dusk falls and the insects begin to swarm, the bats are much closer to their food source. These nocturnal creatures like to consume what we call “M&Ms” but that isn’t the good kind we like to eat. Their M&Ms are moths and mosquitos. So think about that the next time you see them flying around at night. 
 

What is White-nose Syndrome? 

White-nose Syndrome is disease created by a fungus. It effects the bats echolocation when it grows on their faces. This can cause the bat to starve or fly into obstacles. When the fugus develops on the wings it can create holes that make it impossible for the bat to fly. During hibernation the bats normally slow their body systems to allow them to burn through fat reserves slowly. The growth of the fungus on their body causes an irritation that prevents them to go into hibernation for the full season. Infected bats will sometimes wake before the spring season. This can lead to many issues such as freezing to death or starvation. 

 

Why do we walk on the mats after the cave and not before we go into the cave? 

We clean our shoes after going into the cave to stop us from spreading the White-nose fungal spore from Mammoth Cave. Since the fungus is already here we can not stop visitors from reintroducing it. White-nose can live in the cave for many years without being reintroduced.  

Before the fungus made it here we did ask visitors to go through a decontamination process before entering into the cave. Then as infected bats were migrating the fungal spore was introduced to the cave environment. Many of the bats here became infected and the fungus spread.