Unit 7:  External dynamics of the Earth                                      1   2   3

3.5. Groundwater

The result of the geological action of the groundwater on or under the surface of the Earth is known as karst landscapes.

It is due to the carbonation, a type of chemical weathering. The rainwater dissolves the carbon dioxide of the atmosphere transforming it in a weak acid that dissolves the calcium carbonate (calcite) found in limestone.

As the acid water penetrates and dissolve the rock very characteristic erosional landforms are formed:

      - on the surface we can find sinkholes (or dolines), simas, canyons,

        and limestone pavement.

      - under the surface water infiltrates throughout the rock and forms caves

        (or caverns) and galleries.

The dissolved CaCO₃ are deposited in the celling (stalactites) or on the floor (stalagmites) of these underground cavities.

Animation: Cave formation (Classzone)

3.5. What is the difference between stalactites and stalagmites?

        Where do you find them?