Funnel doline in the Hasental
The funnel doline is a karstform of the Swabian Alb. This kind of doline is defined as a solution doline which develops when carbondioxide rich water is temporarily retained inside fractures or depressions in Upper Jurassic rocks. Most characteristic of the solution doline is the funnel; its sharply inclined slopes and the base of the doline are covered with weathered loam. Due to dung input on the fields around, the dolines are preferred sites for plants such as nettle or hogweed. A special feature of the doline in the Hasental is the contributing path: surplus water from the Binsenlache ows into the doline and quickly enters the karstic system via the ponor (opening), which is located at the deepest point of the doline. Thus any harmful substances in the water system end up in the karstic aquifer and pollute valuable water resources. Therefore approximately 5000 dolines on the Alb are protected as „Natural monuments“ by the Biotope Protection Law of Baden-Württemberg from 1992.
The doline is a Geopoint since April 2017.