St. Anna Hole

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As St. Anne's hole is the deepest portion of a steep trench in the riverbed of the Rhine between the Swiss town of Rheinfelden on the left bank of the Rhine and the German Rheinfelden designated on the right bank of the Rhine. It is a tectonic plate boundary on the edge of the Upper Rhine Plain , which runs directly under the Old Rhine Bridge . The ditch reaches its greatest depth of around 32 meters at the legendary St. Anna Loch a few meters below the Rhine bridge.

Position and extent

Old Rhine bridge in Rheinfelden
Schematic representation of the St. Anna Hole

Already around 700 meters above the bridge in the Höllhakens area , the first furrows begin to dig into the river bed of the Rhine. These smaller furrows run in the direction of flow and, over time, merge to form increasingly larger trenches. About 100 meters above the Old Rhine Bridge, the last two ditches unite to form a mighty, steep-walled ditch that runs directly under the middle section of the bridge between Inseli with the former Stein Castle and the right bank of the Rhine. Immediately after the Rhine bridge, the ditch opens into an extensive, shell-shaped basin, the lowest point of which is St. Anna's Hole.

Emergence

The 700 meter long trench near Rheinfelden is located on the southeastern edge of the Upper Rhine Trench , which is part of a rift zone that extends from the North Sea to the western Mediterranean . 35 to 20 million years ago, the earth's surface subsided as a result of stretching from existing faults and sediments were deposited . This phase was replaced by a still ongoing leaf shift , in which the areas east of the Upper Rhine Rift move north-east relative to the areas on the left bank of the Rhine. In the middle of the river bed of the Rhine near Rheinfelden runs a tectonic plate boundary between the Tabular Jura and the Black Forest , which is visible here in the form of a steeply sloping ditch.

The Upper Rhine Graben is generally an area of ​​increased seismicity . On average, a magnitude 3 earthquake occurs every few months that can be felt by people in the immediate vicinity of the epicenter . In the Middle Ages and modern times, earthquakes with destructive effects occurred particularly in the Basel region (e.g. the Basel earthquake of 1356). It is assumed that these earthquakes are connected with the ongoing thrust of the Swiss Jura onto the southern Upper Rhine Rift.

Say

A few centuries ago, the Huns roamed the region. They looted, ravaged and burned entire villages and towns on their way west. When they arrived in Rheinfelden and took the town, its residents fled to nearby forests. Plagued by cold and hunger, they attacked the city one dark night. The occupiers - completely surprised by the attack - are said to have fled the city over the Rhine bridge. They are said to have thrown a captured golden bell over the Rhine Bridge, which is said to have been buried in St. Anna's Hole since then.

According to another legend, the residents of Rheinfeld are said to have thrown everything valuable into the Rhine when the Huns attacked the city. The enemy - cheated of his booty - is said to have taken revenge on the castle mistress Anna and pushed her into the vortex, which has since been called St. Anna's Hole .

In addition, it is said that the electricity here has never released the body of a drowned person.

hazards

St. Anna sculpture on the German bank of the Rhine

The water depth of the Rhine near Rheinfelden is usually three to four meters. Downstream of the rock edges that open the ditch, the water flow naturally forms correspondingly large-scale eddies, which in places and / or at times can also have distinctive vertical components of the flow velocity, both downwards and upwards. In addition, components across and along the main flow. Eddy currents sometimes remain stationary or detach themselves and go with the main flow. Turbulent currents contain both order and chaos. Slow, large-scale eddies in wide and deep waters cause broad, mushroom-shaped or cylindrical bulges of low height, linear notches, and punctiform funnel-shaped depressions according to the laws of currents. The surface wave phenomena ripples and ripples can also be observed due to the often turbulent wind, which form finer structures. All of these phenomena only allow imprecise conclusions to be drawn about the currents in the water body below. Only with favorable lighting, clear water and a view vertically from above or below the surface of the water can particles drifting with the vortex be observed up to a certain visual depth. As a rule, eddies can only be felt by letting them drift, be it as a swimmer or with a board or boat.

The deep part of the St. Anna Hole is extremely dangerous. People have repeatedly drowned here and boats capsized.

The last time a person drowned in St. Anna Hole was in May 2000. The 13-year-old's body was only found about ten kilometers down the river near Birsfelden after seven weeks .

See also

Web links

Individual evidence

  1. ↑ Basler Zeitung ; Article Sankt-Anna-Loch - fabulous tub in the Rhine ; August 5, 1999; Number 180; Page 33f
  2. ↑ There may be a reference to Gertrud Anna von Hohenberg , Rudolf von Habsburg's wife . Since Rudolf was often on the road, he had chosen the former Zähringerburg Stein on the island in the Rhine near Rheinfelden as his family's residence due to its convenient and impregnable location. The imperial insignia (crown and scepter) were temporarily kept there. His wife Anna lived in the castle with her children; Son Karl was born there in 1276, but died that same year. Also in that year the family moved to Vienna forever. In 1445, when the Habsburgs were involved in the Old Zurich War , insurgents destroyed the castle on the Inseli.
  3. ↑ Anna myth ; accessed on June 10, 2015
  4. ↑ Basler Zeitung ; Article Corpse of 13-year-old girl found , July 20, 2000, No. 167, p. 31

Coordinates: 47 ° 33 '19 "  N , 7 ° 47' 21"  E ; CH1903:  six hundred twenty-six thousand three hundred seventy-six  /  267,242