Cave Formations

   Have you ever heard of a stalagmite or a stalactite? If you haven’t, they are long, tall, huge rocks that grow in limestone caves. Stalagmites stick up from the ground and stalactites hang down from the ceilings or sides of the cave. They can be found in either nature made caves or man-made caves and tunnels. Stalactites will form when ground water above the cave that is rich in carbon dioxide, dissolves the mineral calcite, or calcium carbonate, from the limestone directly above the cave. As the water drips into the cave, it starts lose carbon dioxide to the cave atmosphere and leaves behind very little quantities of calcite. The calcite accumulates very slowly forming stalactites. In many cases, this process could take over thousands of years, just to form a stalactite.

   Stalagmites are formed when drops of water don’t evaporate from the ceiling of the cave. Sometimes they splash to the floor. This will build up the stalagmites as the water adds to the limestone on the bottom of the cave. Stalagmites usually have a broader base and a blunter tip than the stalactites. They usually build up a bit slower than the stalactites, but they grow very tall once they have reached the end of their growth. This makes the stalagmites very chunky and thick. Since they grow so tall, they might even join together with the stalactites above. These are called columned stalagmites and stalactites. Over the hundreds of thousands of years that they were formed, they get stronger and get a lot harder to break than before. The stalactites and stalagmites often grow in pairs. this means that the more the stalactite grows, the more water can drip down from it making the stalagmite grows.

   Five years ago, an amateur caver named Robert Brooks hacked a small stalactite from the Brooksville Ridge Cave that he helped discover He was accompanied by a University of South Florida grad student, who sawed off a fragment of the stalactite and who expected the samples to yield valuable climate information. This means that in the past, scientists have found out that stalagmites and stalactites have helped scientists study past climate information. Jason Polk wrote his doctoral dissertation on data extracted from the cone-shaped formations. He had discovered that two stalactites, one older than the the other, has shown him graphic documents of the approach of the ice age 20,000 years ago, when temperatures dropped to around 10 to 12 degrees. Stalagmites and stalactites can also show history of natural disasters and weather patterns. For example, in 1811 and 1812, a major earthquake occurred in the U.S. Midwestern states. Studies show that the stalagmites in nature made caves near the New Madrid Seismic Zone, grew quickly shortly after the earthquake struck. They also grow slowly  in freezing temperatures. This is because the water may get stuck if the limestone cave openings are covered in ice. It may seep through, but it would take longer.

   Stalagmites and stalactites grow very slowly in nature made caves. However, they grow more quickly more quickly in man made caves. They grow about 0.00028 to 0.0366 inches per year. That is so little that they are almost invisible if you look at them compared to seeing a stalactite that has been growing for thousands of years. Soda straw stalactites are the fastest growing stalactites, but the most delicate of them all. Soda straw stalactites form along a drop of water and continue growing down from the cave ceiling forming a tubular stalactite, which resembles a drinking straw in appearance. The internal diameter is exactly equal to the drop of water. Some different names for the stalactites are called popcorn stalactites, mushroom stalactites, dislodged  

stalactites, and even marshmallow stalactites. The stalactites grow about the same amount of inches, but some could be smaller. Other names for the different varieties of stalagmites are button stalagmites, pile-of-plates stalagmites, mushroom stalagmites, mud stalagmites, and lily pad stalagmites. These forms are commonly rare but are normal in some exotic caves.

    In some volcanic lava tube caves, there are stalagmites an stalactites growing. They are basically forms of cooling, dripping lava. There are really only stalactites in the tube caves, because the bottom is usually covered in lava. However, they do exist. In the lava chambers, the stalactites and stalagmites grow more quickly when the lava chambers are full or mostly full. It is just easier to reach when he lava is closer. The lava stalagmites and stalactites are not composed of secondary minerals such as salt or limestone. This also does not make them speleothems which means they are not composed of secondary material, unlike other stalagmites and stalactites.

    Stalagmites and stalactites do not only appear above water and in caves. Stalagmites and stalactites can grow in underwater caves or by coral reefs. Since stalagmites and stalactites need limestone and water to grow, it is easier to grow stalagmites and stalactites because water flows everywhere. Stalactites and stalagmites actually grow 8-10 times faster underwater because there is no possible way that the water can get stuck or trapped. It can flow all around the stalactite or stalagmite and fill it with water. However, there must be some sort of atmosphere to dissolve the carbon dioxide in order to form the stalagmite or stalactite. Otherwise, it would just be limestone.

  

Have you ever seen the inside of a tree trunk once the tree has been cut down? There are rings in which tell you the age of the tree. This is sort of how it works with stalagmites and stalactites. When you cut a stalagmite or a stalactite in half, you may see layers and layers of limestone building up on top of each. The more lines or layers you spot on the stalagmite or stalactite, the older it is. When the drip limestone goes through the ceiling or wall, it has to sit on top of a layer of limestone that has been there . When the limestone drips onto the stalagmite, it falls onto a layer of limestone that was there before. This process will build up the limestone until you can see the different shades of brown and gray in a pattern. You can see this pattern when demonstrating Earth’s rock and soil layers.

   In my report, I have taught you about what stalagmites and stalactites are and how they form. I have told you a little bit of history and how they have effected past research. I have also told you about different kinds of stalagmites and stalactites. You read that layers of limestone might give clues about how old the stalagmites and stalactites might be. I hope you have learned as much about stalagmites and stalactites as I have. This was not an easy topic but it had grabbed my attention when I actually saw them visiting a cave in Ireland. I hope you enjoyed reading my report and now know a little more about stalagmites and stalactites.