Large rockfalls occurred time and again on the Hochkalter massif. In prehistoric times - around 3,500 years ago - more than 15 million m³ of rock slid from the upper Blaueis Combe into the valley. These rockslides impounded the lake of Hintersee. Even today the large glacial erratics in the Zauber Forest bear witness to this monumental event. But even in recent times there have frequently been large rock-falls: