Did you ever wonder how many types of caves there are in America?

By David McClelland

I recently read a story about several spelunkers (persons who enjoys exploring caves as a hobby or for recreation) who explored several different types of caves. The book was written in 1984 by the seven spelunkers who explored together and was titled, "The Grand Kentucky Junction." I wondered how many types of caves exist and researched the subject. I learned a lot about caves, found the subject to be interesting and will share some of what I learned here.

As you probably know, a cave is a naturally formed, underground, air-filled void with an open area or chamber or series of chambers. A cave can contain long, complex labyrinths of tunnels with one or more openings to the outside, such as an overhang. They are often large enough to invite exploration and spelunkers love to do just that.

It is estimated that there are 30,000 caves in the United States and more are being discovered every year. Most caves are either run by private groups or are under the management of the National Park Service, which has 3,900 caves. Of the 120 National Parks, 81 have caves. Show Caves are open to the public while Wild Caves are not and many remain unexplored. Safety is a significant issue and each cave must be declared safe before it can be declared a Show Cave.

You probably know from science classes in school that caves often have calcium rich waters dripping from their ceilings that form stalactites, which are calcite formations attached to the ceiling forming hard rock icicles. A stalagmite is formed when the calcite drips to the floor of the cave and builds up to form an upside down icicle shape. You can remember the difference by using the "c" in stalaCtite for ceiling and the "g" in stalaGmite for ground.

The Guiness Book of World Records (1988 edition) included the Stalacpipe Organ which it declared to be the world's largest natural musical instrument. It is in the Luray Cavern in the Shenandoah Valley of Virginia. The Luray Cavern was discovered in 1878. In 1956, an electrical engineer and accomplished organist, Leland Sprinkle (1908 – 1990), used 37 stalactities in the "Cathedral" section of Luray to create a remarkable organ that produced perfect pitch. Played from a keyboard that resembles a normal organ, the musical tones are produced by a series of rubber-tipped plungers that gently strike each stalactite. Wouldn't you love to see and hear that organ?

Now, for some cave world records: The largest cave is Mammoth Cave in Kentucky. It has more than 348 miles of passageways. It is actually the Mammoth Cave-Flint Ridge System. The deepest cave is Voronya Cave in Abkhazia, Georgia in Russia. It is 5,610 feet deep; i.e., over a mile down to the bottom. The deepest AND longest cave is Kazumura Cave located in Mt. Kilauea in Hawaii. It is 214,895 feet in length (nearly 41 miles) and 3,612 feet deep. The depth is within a volcano from the top to the bottom.

There are several types of caves. Limestone caves are those that form in limestone rock. Karst caves are those that form in water soluble rock. Salt caves are the rarest type. They are formed when salt is formed as it precipitates out of sea water. Sandstone caves form along sandstone cliff faces. Most are caused by mechanical weathering. They are not deep and do not have underground tunnels. Caves also form on ancient coral reefs. Then, there are tectonic caves that are created by mechanical stresses that move rocks. An earthquake can cause a tectonic cave to form. There are also glacier and ice caves. Ice caves are not caves within the ice, but are rock caves that contain ice within their walls. Glacier caves form within ice. As meltwater runs from a glacier, it melts ice along its path. If there are cracks in the ice, the water flows out of the glacier, often leaving long cave passages within the ice. Finally, there are lava tube caves. An example is the area around Mt. Fuji where the Narusawa Ice Cave was originally a lava tube cave made larger by its ice formations. In Lava Beds National Monument in California, there are over 500 lava tube caves.

Finally, we have the Wind Caves. Wind Cave National Park, South Dakota was the seventh National Park to be created and the first cave to be protected within a National Park. Wind Cave has interesting characteristics related to its name. It actually "breathes" air due to an interplay of tunnels, cave openings, and the atmospheric pressure differences between the cave and the surface. It is also one of the longest and complex caves. Its tunnels run for 108.1 miles, fitted under just over one square mile of land. Wind Cave is estimated to be over 300 million years old, making it one of the oldest caves in the world.

Michigan's Bear Cave near Buchanan, Michigan is the only major cave in Michigan and in the Great Lakes area. It was formed in tufa rock which is secondary limestone. Bear Cave is estimated to be 25,000 years old and is resting on a glacier drift deposited during the last ice age approximately 50,000 years ago. The cave measures 15 feet deep, 4 to 6 feet wide, 10-15 feet high and is privately owned. It was used as an Underground Railroad hiding place during slavery days. In 1875, the loot from a bank robbery was stored in Bear Cave. That became the inspiration for the 1903 silent film, "The Great Train Robbery," which is considered a film classic.

We have discussed the ten (10) different types of caves. Another aspect of caves is cave art which goes back to pre-historic times, but that discussion will have to be the subject of a separate blog. May all of your cave explorations be safe and happy ones.