Karst Caves
Some caves are limestone, some are Karst, some are both. Huh?
Karst caves are overwhelmingly located in limestone, so much so that the terms have become almost interchangeable. That is an error, as all karst caves are not in limestone, nor are all limestone caves karst caves. Limestone refers simply to the material of which a cave is formed, while karst denotes the process. Sometimes limestone caves are formed by seismic activity (non-karst cave), and sometimes the karst process happens to gypsum, granite or other non-limestone rock.
How did you come by that name, big cavern?
Karst caves are named for a plateau in the Dinaric Alps in Yugoslavia, and have come to be the name for all such regions. Karst regions are characterized by soluble rocks (limestone, dolomite, or granite), sinkholes, drainage water diverted underground, sinking streams, large springs, and caves. Karst refers to the process by which caves are formed. Another type of cave are erosion caves formed by the action of water by other means than dissolving rock. Lava tubes and caves are formed by volcanic forces.
A little more info, please
Water picks up carbon dioxide from the atmosphere on its journey to earth in the form of rainfall. It picks up much more carbon dioxide as it leeches through biological material in the soil. This dilute solution is slightly acidic, a weak form of carbonic acid. It enters cracks created by tectonic forces in the soluble rock and slowly dissolves the rock. The process is very slow and it takes tens of thousands of years to create a cave.
Karst regions in the United States include the Shenandoah Valley of Virginia, the Cumberland Plateau of Kentucky, the Texas hill country, and northern Arkansas/southern Missouri.
Karst caves feature the characteristic formations we are familiar with such as stalagmites and stalactites. There are also formations of flowstone. They are the result of dissolved minerals being redeposited, slowly building up over time.
Hey, you wanna take it outside?
Cave ecosystems are very fragile. Damage can be done quite easily by breaking formations that took thousands of years to create. Changes to cave chemistry can even be effected by the breath of visitors. Trash dropped in a cave will stay there forever with few natural processes to cause it to degrade. Many caves have been plundered for souvenirs. These same caves have been used as message boards to announce "CM was here", or other foolishness. The balance of life in the cave ecosystem is very delicate. A little carelessness goes a long way for a very long time. Anything which enters the water supply in a karst region will probably become involved with the karst cave environment. That includes sewage from bad piping/septic systems, farm chemicals, road salt used in snow removal, etc. If it's in the water, it becomes a problem for cave ecology.
The world beneath
People have always been fascinated with the world underground. It is the home to many species of insects, plants, and animals. Many of these life forms cannot exist outside of their fragile environment. Other animals who usually live above ground may use caves as refuge from predators or the elements. Caves are sometimes little more than holes in the ground. Others are magnificent cathedrals of delicacy and grace. All deserve our respect and stewardship.