Introduction:
 Most caves are located in karst landscapes and form as water rich in carbon dioxide seeps through the soil and enlarges cracks in the underlying bedrock (limestone and/or dolomite). The soil subsides into these enlarged openings causing a surface depression called a sinkhole. As the size of the sinkhole grows, more and more water is funneled into the area causing more dissolution and further enlargement of the cracks. As swift-moving water moves through the larger cracks, the cracks enlarge even more and form a cave. This type of cave is called a solution cave and is most commonly the type of cave open to the public. The chemical reaction responsible for the formation of sinkholes and caves is as follows:  
CaCO3(s) + H2O(l) + CO2(g) → Ca(HCO3)2
 As water moves through the soil layers, it picks up carbon dioxide from decaying plant material and forms carbonic acid. When the carbonic acid solution enters cracks in the cave wall or ceiling, the cave atmosphere has a lower concentration carbon dioxide. The result is similar to opening a soft drink. The carbon dioxide leaves the carbonic acid reducing the acidity of the solution and causing deposition of the dissolved minerals, in this case calcite. The precipitated calcite forms a ring on the ceiling and the water drips to the floor. Each successive drop of water deposits another ring of calcite until a long delicate “soda straw” formation occurs. Soda straws are the diameter of one drop of water. The straw will continue to grow in length until the inside of the straw fills with calcite. At this point, water will begin to flow down the outside of the straw resulting in cone shaped structures called stalactites. When the water droplets hit the floor of the cave they spread out in a wide pattern resulting in deposition of wider rings of calcite. The resulting formations, stalagmites, will be shorter and thicker than the corresponding stalactites. The chemical reaction responsible for the formation of stalactites and stalagmites is the reverse of the reaction for cave formation. 
Ca(HCO3)2(aq) → CaCO3(s) + H2O(l) + CO
 Depending on the concentration of carbon dioxide and calcium carbonate, growth of stalactites and stalagmites varies from 0.13 mm (0.0051 in) per year to 0.3 mm (0.12 in) per year. Other factors that play a role in the rate of growth are temperature, humidity, amount of precipitation, amount of water moving through the soil, amount of plant life on the surface, and amount of carbon dioxide in the soil.

![pic1.jpg](https://steemitimages.com/DQmdufjQWSyQ82K9eATqTnrdfNs28pgWeRAyreeyWhRMWS5/pic1.jpg)
photo taken with samsung j3