Karst fenster

Karst fenster is a geomorphic feature formed from the dissolution of carbonate bedrock where a spring emerges then the discharge abruptly disappears into a sinkhole. The word fenster is German for 'window', as these features are windows into the karst landscape.

Karst fenster, also known as a karst window, is an unroofed portion of a cavern, revealing part of a subterranean river (Easterbrook). Underground a complex system of caves, known as karst topography; evolve from the effects of water erosion on carbonate rocks such as limestone, dolomite or gypsum. A karst fenster is born from a caving in of portions of the roof of subterranean stream, thus making some of the underground stream visible from the surface (Ritter). Theories in the creation of karst topography and karst fensters involve vadose water above the water table and deep circulating phreatic water (water in the zone of saturation) eroding away subsurface rock. Karst fensters may also form because of weathering from above.

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