The karst

The term “karst” gets its name from the Italian region of Carso (Karst in German, Kras in Slovene), an area near the borders of Slovenia, where this event is mainly diffuse. The landscape is characterized by a typical morphology of calcareous or dolomite rocks, with scarce vegetation, large rocky outcrops and no superficial hydrographic grid.
It is due, mainly, to a combination of different chemical processes which are partly effective on soluble rocks such as carbonatic ones; these processes, with the help of the water, “dissolve” the rocks and they “form again” on the other sites with different forms.
The rainwater, during their passage in the atmosphere and ground, were enriched with carbon dioxide (CO2), which transform the calcium carbonate (CaCO3) of the rocks, generally insoluble, in calcium bicarbonate which is, instead, soluble and easily transportable by the rainwater.
The quantity of calcium carbonate which the water can dissolve depend on its content of CO2. The modification of some chemical equilibrium (i.e. temperature change), can increase the aggressiveness of liquid phase or causing the precipitation of calcite, which it form again in different forms, such as stalactites, stalagmites, travertine, etc..
An other factor which promote this phenomenon is the dense fracture grid, typical of carbonatico rocks, which facilitate the penetration of meteoric water let alone the quantity, velocity, turbulence and temperature of the waters which came in contact with the rocks and which influence the erosion.
So, in the internal of rocks form it a real underground hydrographical grid with streams, waterfalls, little lakes and siphons which, according to the theory of communicating vessels, control the level of the underground caves until, occasionally, the water find a surface point and forms a spring water.