How do stalactites and stalagmites form in caves? ...

[tfester]

How do stalactites and stalagmites form in caves?

Question 2

What factors are necessary in order for a karst landscape to form?

[jharrington11]

Answer to Question 1

Much of the water that percolates into the cave from above first acquires carbon dioxide from the soil and then uses it to dissolve calcium carbonate (by carbonation) from the rocks and sediment it encounters on its way to the cave. Cave air, in contrast, contains a comparatively low amount of carbon dioxide. When the dripping water contacts the cave air, it therefore releases carbon dioxide gas to the air. This degassing of carbon dioxide from the water essentially reverses the carbonation process, causing the water to precipitate calcium carbonate. Eventually, enough calcium carbonate is deposited in this way to form a stalactite, stalagmite, or other depositional cave feature.

Answer to Question 2

The most important factor is soluble bedrock, such as limestone. Climate also plays a rolea warm, humid climate with ample precipitation is most conducive to karst development. In arid climates, karst features are typically absent or are not well developed, although some arid regions have karst features that originated during previous periods of geologic time when the climate was much wetter. Compared with colder humid climates, warmer humid climates have greater amounts of vegetation, which supplies carbon dioxide to subsurface water. Carbon dioxide is necessary for carbonation of limestone and it increases the acidity of water, which encourages solution in general.