The active rock glacier «Grosses Gufer» moves downhill several centimeters per year. The rock glacier consists of a mixture of rock, debris and ice and its presence indicates permafrost soils. Permafrost signifies that the ground is frozen all year round, even in summer only the upper soil layers are thawing. The frozen ground will not allow the water to infiltrate, therefore permafrost soils are often heavily soaked in summer. Rock glaciers occur with low temperatures and permafrost soils, but need also plenty of debris and a sufficiently steep slope. If you travers the slope of debris in midsummer you might hear the underground water courses and in some places the meltwater with icy cold temperatures below 1 °C is leaking from the so-called block front sources. Earlier, the water from the "Grosses Gufer" was cached and channeled through the bisse "Riederfurka" to irrigate the pastures on the Riederalp.