In the legendary Martinsloch, two zones of weakness intersect: a soft, flat-lying, dark marl layer and a steeply standing fault surface. In this area, erosion was able to remove the limestones more quickly, and the Martin's Hole was formed with a diameter of more than 15 metres. On two days in spring (13/14 March, in leap years on 12 March) and autumn (1/2 October), the sun's rays strike the church of Elm through the Martinsloch.