Schällbach is a stream on the surface that has its source in the meadows above Breitenbach. It snakes through the woods until it seeps into the ground at several drainage sites a short distance before and after Schällbachponor. The Schällbachponor is a much older, fossilised stream drain. The vanished water can be found at the lowest point of the cave, where it collects in a siphon and reappears in the pipe-spring in Kaltbrunnental (as demonstrated with dye-tracing tests).

 

Ponor caves

Ponor is the serbo-croat term for a drainage site of a stream (or lake). Usually streams are not present in karst. But as soon as water from neighbouring regions or from areas sealing it off on the surface (e.g. cover from a moraine) reaches the karst below ground, it is swallowed up. Occasionally such stream drains are accessible to man. We call them ponor caves.
They are very different from the random runoff of rainwater or water from melted snow.
In most of the karst areas in Switzerland random drainage is far more common than the spectacular localised disappearance of a stream into a ponor. Ponors are not unusual, but mostly occur in the form of narrow clefts or are blocked up by washed-in debris (clay, rubble, tree branches) making them inaccessible to cavers. (The position of the drainage sites is constantly changing, allowing only short periods of time for the formation of large cavities). Real ponor caves are rare
in Switzerland, especially in the Jura region.