Ruinaulta
Ruinaulta, also known as the Rhine Gorge, is a canyon in the canton of Graubünden, Switzerland, carved by the Anterior Rhine between the villages of Ilanz/Glion and Reichenau. It was formed by the prehistoric Flims rockslide, which blocked the river and eventually gave rise to the present-day gorge.
The Ruinaulta extends for about 14 kilometres and is characterised by white cliffs, forested slopes, quiet lakes, and varied habitats supporting a diversity of plant and bird life. It can be explored on foot, over water, or by bicycle, and the Rhaetian Railway passes through the gorge, with stations at Valendas-Sagogn and Versam-Safien.
Ruinaulta lies within the Swiss Tectonic Arena Sardona, which was inscribed as a UNESCO World Heritage Site in 2008.
Formation
The Ruinaulta lies between the Surselva and Imboden regions in the canton of Graubünden, extending from Castrisch to Trin along the upper valley of the Anterior Rhine. The gorge cuts through deposits of the prehistoric Flims rockslide, in which an estimated 8–9 cubic kilometres of rock collapsed from the Flimserstein and neighbouring peaks around 9,500 years ago, in what is considered the largest known landslide in the Alpine region.The rockslide debris blocked the river, creating Lake Ilanz, which lasted for several centuries before gradually draining as the Anterior Rhine cut through the material. The present-day gorge features a meandering river with alternating gravel and sandbanks, rapids, and river terraces, bordered by cliffs rising to heights of up to 350 metres.
The steep walls of the gorge are known locally as Ruinas, a term from the Romansh language meaning “pillar,” “gully,” or “scree slope”; aulta means “high.”