Rhine knee

The whole Rhine knee lies within Swiss territory and is settled by the city of Basel and its adjacent municipalities Riehen and Bettingen.

[citation needed] The Basel knee arose in the last glacial period (Würm glaciation), when the river flowed directly from today's Grenzach-Wyhlen west of the city to the area of Weil am Rhein in the north.

The northern Wiese tributary transported large rubble and gravel sediments from the Feldberg glacier into the Rhine Valley, enforcing the river's characteristic bend to the south.

[citation needed] The Upper Rhine again changes its flow direction from west to north at another bend near the German town of Bingen and the mouth of the Nahe tributary.

[citation needed] The Rhine narrows at the site are called Bingen Hole (Binger Loch), marked by the Mouse Tower on an island in the river and uphill Ehrenfels Castle.