Flims Rockslide

The Flims rockslide took place 9480-9430 years ago (calibrated) instead. It is equipped with a volume of between 9 km ³ and 12 km ³ of the most extensive alpine landslide event ( approximately 300 times greater than the landslide of Goldau and about 1200 times greater than the landslide of Elm ) and worldwide one of the largest currently known landslide events at all. On the transition of the sliding surface in the north to the mass of debris in the south, the resort of Flims. North of Flims rock walls rise up to 350 meters high and to the south is a densely wooded, confusing hills with lakes and a wild canyon, the Ruinaulta. The landslide is hidden for travelers through the forest; because the debris cone for farmers is of no interest, he remained a wooded area. The forest is for the Vorderrheintal namesake: The Romanesque Surselva means " if the forest ".

Description

The crack initiation point is located at about 2,700 m above sea level. M., Flims, located at about 1,100 m, and the filled-in glacial trough valley at about 600 m. The fall mass consisted of the Mesozoic limestones, which were 300 to 500 meters thick and slid down on a slide from 20 ° to 25 °. The valley must have been around 1500 meters wide. The debris are piled up to about 750 meters and cover an area of ​​some 52 km ². Most of the fall mass was completely smashed, although the original structure was retained with the partial layering yet. On the wooded surface are countless huge limestone blocks. The Anterior Rhine was dammed by the landslide. It originated as a large reservoir, the Ilanzersee, which is, however, long since drained by the Ruinaulta. Obviously, however, the Rhine is not reached on the original valley floor.

Dating

In 1997, a first date according to the C- 14 method of wood from the Rabiusaschlucht by Andreas v. Poschingerstraße and Uli Haas took place. By Susan Ivy - Ochs this age was confirmed with the cosmogenic radiation method 2005. 2005, these data have been defined by Gaudenzdorfer Deplazes and Flavio Anselmetti. They had lake sediments dated to the fall and also even wood in the fall mass found. There was a calibrated age 9480-9439 years ago. Works by Clemens Augenstein of sediments in Dachlisee ( 1,137 m) at Obersaxen could result in no clear dating. No action of glaciers was found, contrary to earlier assumptions on the landslide mass. The nearby Taminser landslide (volume unknown) must be on the dating of Ivy - Ochs at a similar time ( ± 1000 years) as the Flims rockslide be done. V. Poschingerstraße assumes that he is divested prior to the Flims landslide and the Rhine Valley has blocked with a dam.

In the maximum stage of the Anterior Rhine glacier must have been well over 5 km over 1500 meters thick with a width. Flowing ice and wants to expand. The result is a tremendous pressure not only downward, but also to the mountain flanks. This pressure can gouge the rock together with the entrained in the ice rubble and move layer packets. This results in shear zones, thereby loosened layer packages and brittle. In these shear zones into water flowed. After the glaciers had retreated, the permafrost looked even gradually disappeared several centuries later. The delayed release of the landslide could be due to the thawing of permafrost, as during the Ice Age in the Alps frost depths are demonstrated by several hundred meters.

Effects

Remote effects of the Flims rockslide extend into the Lake of Constance, where sediment anomalies were found. In Domleschg to Thusis to gravel sediments are mobilized according to current knowledge by the Flims rockslide and flowed into the Upper Rhine Valley, see. The Chur Tomahügel be causally linked to the Flims fall. As a result of the landslide caused several landslide dams: the Ilanzersee, Versamer the lake, the lake of Mulin, the Laaxersee, the lag and the lag Segnas di Plaun. The largest was the Ilanzersee. The landslide mass below only in a few places, the level of 1,000 m above sea level. M.. Presumably the same is true for the area of ​​today's Ruinaulta. Overflows are nowhere observed. But the mirror of Ilanzersees seems never to have exceeded the maximum level of 936 m, at least there is no indication.

After the landslide was the filling of the Ilanzersees several years, probably soon after which a dam failure occurred. However, the lake emptied itself not complete, but remained at the level of 820-840 m above sea level consist of at least 1000 to 2000 years. This is evidenced by lake sediments. The Ilanzersee should have exhibited an initial volume of more than 3 cubic kilometers, the lake left behind in ³ 820 m height, nor of 1.5 km. The fall mass is strongly compressed in many areas, high stability causes the sliding mass is yet no hard rock.

The mass of debris is degraded at Versam in a gravel pit.

Visit

• A very good overview over the whole landslide area offers the hamlet Dutjen above Valendas; the narrow carriage road has been renovated a few years ago (even walk, about an hour from Valendas ). That access to Riein is subject to approval.

• With the cable car from Flims Dorf on the Cassonsgrat the trailing edge of the landslide can be reached.

• With just a few tunnels the Rhaetian Railway and Glacier Express ride through the Ruinaulta. Three stops are located directly on the Rhine front in the canyon: Trin Station Versam - Safien and Valendas - sagogn. By car, the canyon is accessible only at certain points, there is little parking.

• The path of the Anterior Rhine through the Rhine Gorge can be hiked to about two thirds of the way. A continuous footpath is not, but is being planned. Some points of the canyon are, except for mountaineers, inaccessible.

• In Conn., located in Flims forest and thus on the actual cones of "floats" the spectacular viewing platform Il spir over the cliff. Conn can be reached on foot or by mountain bike from Flims Laax or out. In the forest, one encounters the Conn - Bächli, a historic irrigation canal (similar to the Valais irrigation channels ), which supplies the meadow Conn in an otherwise waterless large forest with water management.

• For experts in whitewater the passage on the Rhine front is possible. Different providers offer boat trips to the canyon.