Karst is characterized by the dissolution of soluble rocks such as limestone, dolomite, and gypsum. Karst areas are typically characterized by subsurface drainage systems with sinkholes, dolines, and dry valleys at the surface and caves underground.

Karst is a geological phenomenon, first described in Slovenia. This area is called Kras in Slowenian or Karst in German, which means rocky place. Since then all areas with a similar geological situation are called Karst Areas.

The basic aspects of karst areas are soluble bedrock, cracks and water. The rain water is able to dissolve small amounts of rock and carry them away. Most rocks are not permeable to water, but sedimentary rocks have horizontal layers called bedding with so-called bedding planes. Additionaly, during times of up and down movement, the rocks are bent and get mostly vertical cracks. When water follows this cracks, it dissolves the rock and forms caves and caverns.

Common rocks for karst areas all over the world are:

  1. Limestone (calcium carbonate CaCO3)
  2. Dolomite (magnesium calcium carbonate CaMg2CO6)
  3. Gypsum (CaSO4 + H2O)
  4. Salt (NaCl)
  5. Sandstones to a limited extent. They are soluble depending on the chemical composition. It is often referred to as pseudokarst.
  6. Quartzite (SiO2). However, this is a special case, since quartzite is soluble only under extreme temperature conditions and quartzite karst is therefore known only from some regions in the tropics.

There are caves in other kind of rock, but they are not karst features! Typical features of karst areas are:

The type of erosional forms which the karst takes, depends on many variables: