The Ablach is a right tributary of the Danube. It rises on the European Watershed, which is only a hint in this area, from the Mindersdorfer Aach in the municipality of Hohenfels in the Landkreis of Konstanz. It is about long. Geology During the Riss ice age, about 120,000 years ago, the Ablach flowed into the Danube at Engelswies, because its original valley was covered by the ice. The ice blocked the Danube, and the Danube formed a lake between Geisingen and Spaichingen. When the water level of this lake reached above mean sea level, it overflowed into the Neckar valley at Spaichingen. About 100,000 years ago, the ice melted and the Ablach took its current course. Before it was straightened, the Ablach meandered through its valley. The Ablach Valley in the broadest sense is the area between the Großer Heuberg in the north and the Linzgau in the south Course The upper reaches of the Ablach flow through the Schwackenreute Plateau, past the towns of Bichtlingen and Schnerkingen. In Meßkirch, the Grabenbach joins from the left. the Ablach then flows past Igelsweis and Menningen, where, in the Middle Ages, the Ablach fed the moat around the water castle. Before Göggingen, the Ringgenbach joins from the right and some of the Ablach's water is diverted into a mill channel. Past Göggingen, this channel joins the Ablach again. The Ablach then flows past a village named after it, Ablach, and then towards Krauchenwies and through the local royal park. After Krauchenwies, it flows in a graded bed past Zielfingen, amidst a collection of water-filled gravel pits. A weir near the Südsee III restaurant diverts some the Ablach's water into a channel where it drives a water mill and a saw mill. Past this sawmill, the water is led back to the Ablach, only to be diverted again for the next saw mill. The diverted water then flows through Mengen, while the original course flows through Ennetach. The two streams are reunited south of Blochingen, shortly before the Ablach flows into the Danube. The last of the Ablach flows along a former bed of the Danube. This arm of the Danube was cut off when the Danube was straightened. The Mindersdorfer Aach, watershed and bifurcation The headwaters that are currently the upper part of the Mindersdorfer Aach were originally the headwaters of the Ablach. The Stockacher Aach had a favourable gradient for