Additional threats exist for rockfalls and avalanches. Other mass movements include icefalls, landslides, and rockfalls. Corresponding decrees from the 14th century deal with protection against avalanches, rockfalls and flooding. Rockfalls and landslides were also reported in the region. The canyon itself still shows activity in the form of rockfalls and landslides. Rumours about a "staircase", later probably obliterated by landslides and rockfalls, were reported in 1955. Recently erupted volcanic domes are unstable and can collapse, generating small to large rockfalls. Normal weathering also weakens fractured volcanic rock and contributes to small rockfalls. In high mountains rockfalls may be caused by thawing of rock masses with permafrost. It lies on a talus cone of debris from old rockfalls. Typical changes include intense gullying, serrated ridges, and major and minor rockfalls. The unstable geology of the escarpment resulted in rockfalls, forcing the closure of the road. The resulting holes become enlarged to arch proportions by rockfalls and weathering. It may be subject to natural rockfalls as the erosion process continues. Bond runs around the mine, avoiding rockfalls and long drops.