Karst museum

The Kras

The Kras is the area between the sources of the River Ljubljanica and Bay of Trieste, which thanks to its famous caves, intermittent lakes, sinking rivers and river sources, rocky surface and dolines, has always aroused interest among both locals and travellers. As this is where the first scientific research of karst landscapes and phenomena took place, the Kras, or “classical karst” has become the “locus typicus” of such landscapes around the world, giving its name to this natural phenomenon.

Authors: Andrej Mihevc, PhD and Slavko Polak



To dissolve a few milligrams of lime we need one litre of rainwater.

A karst landscape can appear only where there are water-soluble rocks like limestone and dolomite. Another name for them is carbonate rocks, after the main mineral they contain – calcium carbonate. Both rocks appeared as sea sediment. Karst stone has been used by man for building since prehistoric times. In some areas of the Kras, the traditional karst houses are built almost fully from stone cut by hand.

Limestone is a rock primarily made up of water soluble calcium carbonate, CaCO3. One litre of pure rainwater can dissolve a few milligrams of lime. A similar rule applies to dolomite rock. The solubility increases when carbon dioxide (CO2) from the air or the soil also dissolves in the water, creating a mild carbonic acid (H2CO3). The acid dissolves the carbonate rock, resulting in the appearance of calcium (Ca2+) and hydrogen carbonate ions (HCO3). This process takes place in both directions. One litre of rainwater percolating through the soil to the limestone can thus dissolve up to a few hundred milligrams of calcium carbonate.

H2O + CO2 = H2CO3
CaCO3 + H2CO3 = Ca2+ +2(HCO3)-
Ca2+ + 2(HCO3)- = CO2 + CaCO3 + H2O

Karst cave

The most typical karst formation is a karst cave.

The closely connected research disciplines that study the karst as a natural landscape type are referred to collectively as karstology. The main disciplines involved are geology, geography, geomorphology and biology. Caves are the most typical karst formation, since the shaping of the karst is dependent on the underground flow of water; this is why karstology pays particular attention to caves.

  • Geology is the study of the origin, development and structure of the Earth.
  • Geomorphology studies the relief of the Earth’s surface of land and seabed.
  • Biology is the study of life. It studies the behaviour of living and extinct organisms on the Earth.


Living world of the karst underworld

Slovenia’s classical Karst or Kras is one of the world’s hotspots of subterranean biodiversity. In the karst caves of Slovenia, between 400 and 450 species of cave fauna have been identified. The largest and best known is the Proteus. But in the dark environments of the karst underworld, where food is sparse, a whole series of invertebrates adapted to life in caves can be found. These are mainly tiny representatives of cave snails, crabs, arachnids, centipedes and insects.

Cave-dwellers: a stone marten, edible dormouse, lesser horseshoe bat, Schreiber’s bat, Proteus, slenderneck beetle, cave crickets, cave centipede, cave Diplura, cave herald snails, subterranean water snails, cave tube worm, cave hydrozoan, subterranean triclads.

The first representatives of cave-dwelling animals in the world were described using specimens from the Slovene Kras. Early natural scientists discovered the first cave animals particularly in Postojna Cave and other nearby caves, which gives Postojna the justified reputation as the cradle of speleobiology – a biology discipline involved in the study of subterranean life.

Shortly after the discovery and scientific description of the first cave slenderneck beetle in Postojna Cave in 1832, the interest in science circles for the search of animals in caves increased. With time, the study of cave fauna, which we must now extend to the study of life in subterranean habitats, has become of interest to several researchers. And so, even on our ground, a new branch of biological sciences named SPELEOBIOLOGY, or the science of studying life in the underworld, was born. Speleobiology thus examines life in all subterranean environments, not only in caves, which makes the use of the term cave biology less suitable.

Authors: Andrej Mihevc, PhD and Slavko Polak

Source: Green Karst


Kolodvorska cesta 3, Postojna

+386 (0)5 7211 090





One Comment Add yours

  1. Carolyn Lyness says:

    We really enjoyed our visit to your museum.
    Can you please let me know the name of the graphic artist who designed the red dragon motif on the t-shirts you have for sale


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