The Sax-Schwende-Bruch is a striking fault in the Alpstein area and forms a geotope of national importance. At this fault line, all mountain ranges in the eastern cross-section were shifted to the north.
The eponymous places Sax in the St. Gallen Rhine Valley and Schwende in the Appenzell region mark the ends of the visible shift. The break runs from Sax in the south to the Saxer Lücke ( ), his first pass crossing. On the other side of the Saxer Lücke lies the Bollenwees alpine region , where the shifted east side with the folds of the "boots" docks the Fählensee in its fold . From Bollenwees, the break runs well visible with a rock break from the Stiefelwald northwards into the «Chalberweid» area and rises again to the Bogartenlücke, at 1,709 meters above sea level around 50 meters higher than the Saxer Lücke. From the Bogartenlücke the visible break goes in two steps down to Wasserauen . To the north of Wasserauen, the Alpstein chain with its rock on the break remains in the form of two rock faces east of the Ebenalp without continuation.