Zaininger Hüle

water on the volcano

in the middle of the village of Zainingen, part of the municipality of Römerstein, there is a rare scene for the Swabian Alb: a tranquil, reed-lined body of water where water lilies float and dragonflies dance – the Zaininger Hüle. It owes its existence to the volcanic past of the Alb.

Magmatic rock, known as volcanic tuff, forms the subsoil of Zainingen. The village lies on a volcanic vent and in the middle of a so called maar. These volcanic explosion craters are created by steam explosions when rising magma meets groundwater. Such a process occurred here around 20 million years ago during the Neogene period (Late Tertiary). At that time, there was active volcanism in the Swabian Alb and numerous volcanic eruption tubes pierced the older Jurassic rocks in the Swabian Alb. The “Swabian Volcano” in the area around Bad Urach and Kirchheim comprises around 350 proven locations where magmatism can be detected underground and above ground. Geological maps show that many villages are situated on former volcanic vents. Böhringen and Donnstetten nearby are also among them.

Volcanic tuff retains water, creating small natural wetlands known as “Hülen.” Natural bodies of water like these are extremely rare on the Alb plateau, as precipitation normally drains very quickly into the karstified subsoil. Water shortages were a constant problem for the inhabitants of the Alb. Only in a few places, such as here in Zainingen, did Hülen provide vital water for livestock, daily use, and firefighting. People settled around them early on, and settlements sprang up. Place names such as “Berghülen” or “Breithülen” still bear witness to this today. (However, water-retaining clays in the subsoil are responsible for the Hülen there).

The Zaininger Hüle, the last of four former ponds in the village, is now protected as a natural monument. Until 1921, they provided the water supply for the Alb village, and it was only then that Zainingen was connected to the Alb water supply.