How is Karst Formed?

Karst is formed in carbonate bedrock through what is called the carbon dioxide (CO2) cascade.

The main steps of the CO2 cascade are:

Rain picks up CO2 as it falls.
The rain trickles into the soil where it picks up more CO2 and becomes a weak solution of carbonic acid.
The carbonic acid solution percolates through the ground into joints and fractures in the bedrock.
The bedrock gradually dissolves, creating underground streams, caves, etc.

Run your mouse over the picture to see how the cascade works.

Figure 1-2: The carbon dioxide cascade.