Sterkfontein Caves - Part 5

Many beautiful structures – including stalagmites and stalactites – form inside caves as carbonic acid carrying limestone, drips through cave roofs onto their floors. Structures inside a cave may take millions of years to develop.

Some of the geological structures which may develop inside a cave include:

Speleothem
“Speleothem: is a general geological term for a calcium carbonate deposit in a cave, including formations such as stalactites, stalagmites and flowstones.

Flowstones
Flowstones are speleothems on the walls and floors of a cave formed from a gradual flow of water over a relatively broad area.

Stalactite
The term stalactite comes from the Greek word stalaktos, which means “dripping” because these other-worldly formations “drip” from the roofs of limestone caves. Essentially, water reacts to carbon dioxcide to form carbonic acid. It then seeps slowly through the roof of the cave, depositing calcium carbonate which hardens and build up over time to form a stalactite.

Stalagmite
Stalagmites are corresponding formations on the floor of the cave to stalactites. Stalagmites rise from the floor in a build up of calcium carbonate over time, from mineral-bearing water dripping from the roof of the cave. The term stalagmite comes from the Greek word stalagma, to “drop”.

Column
Sometimes stalactites and stalagmites meet, forming a pillar or column of rock-hard calcium carbonate.

Helictite

A formation of calcium carbonate in a cave that grows in a twisted, curled fashion, like a helix (hence the name), seemly defying the laws of gravity.