Ponor


A ponor is a natural opening where surface water enters into underground passages; they may be found in karst landscapes where the geology and the geomorphology is typically dominated by porous limestone rock.

Etymology

The word derives from the proto-Slavic nora. The word "ponor" itself comes from Slovene in which the word ponor has the same meaning.

Description

Whereas a sinkhole is a depression of surface topography with a pit or cavity directly underneath, a ponor is kind of a portal where a surface stream or lake flows either partially or completely underground into a karst groundwater system. Steady water erosion may have formed or enlarged the portal in rock, in a conglomerate, or in looser materials.

Prevalence

Ponors are found worldwide, but only in karst regions. The entire Adriatic watershed within Bosnia and Herzegovina sits on Dinaric karst, with numerous explored and probably many more unexplored ponors and underground flows. There are also several places in southeast Europe with the name "Ponor" due to associated karst openings. There are significant geological ponors in the Carpathian Mountains, the Dinaric Alps, Greece, Turkey, and parts of the southern United States.