The key difference between stalactites and stalagmites is that the stalactites hang from the ceiling of caves whereas the stalagmites rise from the floor of a cave. Furthermore, the stalactites have a pointy edge, but the stalagmites have a thick edge. Also, they both differ on the conditions for formation.
Stalactites and stalagmites are two different formations that occur inside caves. We can categorize them as mineral deposits because these formations form due to the accumulation or deposition of different materials. These two types differ from each other according to their location inside the cave; either on the ceiling or the floor.
What are Stalactites?
Stalactites are formations that hang from the ceiling of caves. We can find them in hot springs and manmade structures such as bridges, mines as well. These formations form due to the deposition of different materials which are soluble that can deposit as colloids or materials in suspensions. Moreover, these materials should melt easily as well, to form these stalactites. These formations mainly contain the followings in common.
Speleothem is the most common example for these formations. It is a form of a stalactite that forms in limestone caves. However, people often misunderstand that all the stalactites are Speleothem, which is not true. There are many other forms of stalactites. Ex: Lava stalactites, ice stalactites, concrete stalactites, etc.
Since limestone stalactites are the most common, let us discuss a little bit more about them. They occur in limestone caves. The formation is through the deposition of calcium carbonate and other minerals that precipitate from mineralized water solutions. Limestone contains calcium carbonate that can dissolve in water that contains carbon dioxide. This dissolution forms a calcium bicarbonate solution. This solution travels through the cave until it finds an edge. If this edge is on the roof of the cave, the solution will drip down. Then when air comes in to contact with this edge, calcium bicarbonate converts into calcium carbonate, releasing carbon dioxide. Likewise, a hanging stalactite occurs.
What are Stalagmites?
Stalagmites are formations that rise from the floor of caves. These are a type of rock formations. They form due to the accumulation of materials that deposit on the floor from ceiling drippings. These formations also contain the same components as in stalactites (components are listed above). There are several forms such as limestone stalagmites, lava stalagmites, ice stalagmites and concrete stalagmites.
When considering the formation of limestone stalagmites, it occurs under certain pH conditions. They form through the deposition of calcium carbonate and other minerals which precipitates from mineralized water solutions. Limestone contains calcium carbonate. It can dissolve in water containing carbon dioxide. This forms a calcium bicarbonate solution. There, the partial pressure of carbon dioxide in water should exceed the partial pressure of carbon dioxide for the conventional growth of stalagmite. Moreover, we should not touch the edge of stalagmites because our skin oils can change the surface tension of the edge. It can affect the growth of the stalagmite. In addition to that, the dirt on our hand can permanently alter the color of the stalagmite.
What is the Difference Between Stalactites and Stalagmites
Stalactites are formations that hang from the ceiling of caves. Whereas, the stalagmites are formations that rise from the floor of caves. This is the main difference between stalactites and stalagmites. More importantly, the formation of stalactite depends on the rate of dissolution of calcium carbonate and the rate of conversion of calcium bicarbonate into calcium carbonate on the edge of the stalactite. But, in the stalagmite formation, apart from the rate of dissolution of calcium carbonate and the rate of conversion of calcium bicarbonate into calcium carbonate on the edge of the stalagmite, the formation also depends on the pH of the water and surface tension of the edge. The following infographic presents the difference between stalactites and stalagmites as a side by side comparison.
Summary – Stalactites vs Stalagmites
Stalactites and stalagmites are two different formations that we can observe inside caves. The key difference between stalactites and stalagmites is that the stalactites hang from the ceiling of caves whereas the stalagmites rise from the floor of a cave.
1.”Stalactites in Wind Cave”By National Park Service of the United States of America (Public Domain) via Commons Wikimedia
2.”2078879358″ by Börkur Sigurbjörnsson (CC BY 2.0) via Flickr