Belchenflue Pass (el. 1099 m.) is a high mountain pass in the Jura Mountains between the cantons of Basel-Country and Solothurn.The pass is also called Bölchen by locals. The name came originally from Celtic from the sun god Belenus. The nearby peak of the same name (el. 1099 m.) was an important marker for the tribal calendar establishing the seasons.
Along with the peak of the same name in Alsace (Ballon d'Alsace), it allowed the establishment of the winter and summer solstice.As is the case with much of the Jura range, the cliffs are formed of hard oolithic limestone, which has been exposed as the softer stone above it has eroded.The pass forms the divide between the watershed of the Aare River in the south and the Ergolz in the north. Both flow into the Rhine. To the east are the Challhöchi and Unterer Hauenstein passes.
Elevation: 1,099 m (3,606 ft)