A cave is an opening in the earth, large enough for a man to get into. To be a true cave it needs to expand beyond the reach of natural light. The study of caves is called speleology. In order to truly understand this science you’d need to know about biology, geology, hydrology and archaeology. This article will explore how limestone caves are formed.
Limestone caves are in a category of caves called solution caves. They are formed in carbonate and limestone rock. Limestone caves are created by the power of slow moving water. In fact, they are often described as a big part of a subterranean plumbing system.
When it rains the water soaks into the ground. It travels through the cracks and the pores of the rock and the soil. There comes a point when the pores and the rocks have reached their saturation level and the water has no place to go. The term water table describes this area where the water really begins to have no place to go.
Rainwater absorbs carbon dioxide. The water forms a weak carbon dioxide solution. The acid slowly dissolves calcite and creates solution cavities. It is a chemical excavation process all engineered by nature.
The second stage of limestone cave development happens when the water table naturally lowers. The limestone caves are now surrounded in an unsaturated zone where air can enter. This adds to the deposition for calcite, and dripstone formations begin to form. This is the reverse of the process of solution.
Again, it is all about the chemical process. Water as it passes down through the limestone above the cave still possesses carbon dioxide. When it reaches the cave it is similar to opening a bottle of pop. The acidity of the water is reduced and the calcium bicarbonate is dripped into the cave.
Stalactites are formed from the ceiling of the cave as part of the dripstone process. They are formed by a slow drip process. Stalagmites form under the stalactites where the drips are faster and collect and build from the bottom up.
Soda straws are slender hollow stalactites. They are made from the evaporation of the carbon dioxide. When there are several of these in a grouping they are called a bacon strip.
Flow formations are created not by drips, but by a larger flow of water. These are often very colorful and dramatic.
For anyone interested in visiting a limestone cave, there are many. They are plentiful and often found in state or national parks. You now know how they are made; go check them out in person.
