Wikipedia quote:
"A spring flood cone is created by clayey and silty weathering rock washed in by the precipitation. This is washed into sinkholes (earthfalls) and rock cracks during heavy precipitation. Turbulence and the water pressure prevent the water from clearing underground. This water arrives in springs in the valleys The suspended matter settles in a circle around the opening of the spring on the grass. This grass grows through the embankment and so the spring floating cone continues to increase. Spring floating cones can only arise on meadows and pastures, not in forests. The beginning of their formation one therefore appreciates the end of the Neolithic period. "
"Spring floating cones are a special feature of the karst of the Paderborn plateau because they only occur there. They are temporary sources on shield-shaped elevations. They formed in the valley bottoms of the Alme and Altenau, among other things. There are 17 in the area of the Paderborn plateau This spring floating cone, which have a height of up to 2 meters and a diameter of up to 50 meters, some of which have been wholly or partially destroyed in the meantime by road construction and drainage Project to observe the alpine pasture discovered. The largest spring cone is in the valley near Henglarn. "