The Reesberg Doline – I couldn't make any sense of this mysterious term at first. From the Heimkehle karst cave near Uftrungen and the Reesberg (325 m above sea level), I climbed a narrow path with a few steps through the forest area of the Old Stolberg up to the doline, a deep depression in the middle of the mountain. There, layered springs emerge from the Bunter sandstone. This gypsum-rich water flows downhill just a few meters and then disappears into the gypsum-covered main anhydrite. Over the centuries, this formed a deep solution doline. Considerable investment has been made at the Heimkehle in recent years. A beautiful playground with picnic areas, numerous information boards and interactive stations, as well as the nature park information center, invite you to linger.