Ge 4/4 II # 626 of the Rhaetian Railway is pulling the PE (Panorama Express) 902 GLACIER EXPRESS from Zermatt via Brig-Andermatt-Chur to St.Moritz, through the gorge of the Vorderrhein, called Ruinaulta, between Versam-Safien and Trin. The Ruinaulta was formed after the Flims landslide almost 10,000 years ago. At that time, more than 10 billion cubic metres of rock broke off between the Flimserstein and the Piz Grisch and buried the Vorderrheintal between the present-day villages of Castrisch and Reichenau under a mass of debris several hundred metres thick. Since the Vorderrhein could no longer drain away, a lake was dammed over a length of about 25 km. In the course of time, the river cut deeply into the landslide masses and the resulting lake could drain away completely. What remained was the Ruinaulta with its steep limestone scree cliffs in imposing erosional formations.