Flims rockslide

The Flims rockslide happened about 10,000 years ago (8000 BC) in eastern Switzerland. It is the biggest known landslide incident in the Alps, and the biggest worldwide whose effects are still visible, moving some 12 km3 (2.9 cu mi) of rock, about 300 times that of the historic Swiss Goldau landslide. The town of Flims can be found at the line where the slip surface disappears under the debris. North of Flims the rock face of Flimserstein stands 350 metres (1,148 ft) high whereas more westerly the slide surface is clearly visible. South of Flims is a huge hilly debris area that has been forest ever since, as this area is not suitable for farming, firstly for its shape and, even more for its lack of water. The river Rhine crosses this debris in a gorge called Ruinaulta. The Rhine still runs in debris, which shows that it has not yet reached its level as before the incident. The highest hill in the debris area is almost 200 metres (656 ft) higher than Flims at the end of the sliding surface.

Rhine cutting through Flims Rockslide debris
Rhine cutting through Flims rockslide debris


Debris area seen from the south
Flims lies behind the hill

The top of the slide surface can be found at 2,700 metres (8,858 ft) above sea north of Flims at Fil de Cassons; the end of the slide surface is at about 1100. The pre-slide valley would have been at 600 metres (1,969 ft). The rock is Mesozoic limestone, including Mergel; the angle of slide is (only) 20° to 25°. Debris covers 40 km2 (15 sq mi). Pressure baked the debris together to a somewhat stable rock. Given the river Rhine as a base of the valley, the debris is as high as 600 metres (1,969 ft). This debris dammed the Vorderrhein and created a lake in the Ilanz area. The level of the lake was found to have been at a maximum of 840 metres (2,756 ft) above sea level, which results in a lake some 10 miles (16 km) long.[1]


Clemens Augenstein from Geologisches Institut der ETH Zürich explored with Professor Flavio Anselmetti the sediments at a small lake called Dachlisee at 1,137 metres (3,730 ft) near Obersaxen. The lake with no river flowing into it lies opposite Flims, some 6 miles (9.7 km) away. They were looking for dust, as an incident of this size would have produced a giant dust cloud. Drilling five times into the sediment they found embedded limestone dust. Using carbon dating the limestone dust was found to be 10055 years old (plus/minus 195 years).

A second source is wood, that was found inside the debris in the region, some 2 miles (3.2 km) upstream of the mouth of river Rabiusa, which was covered by massive rock identified from the Fil de Cassons area, hence reaching this point at the event; too old for the Dendrochronology line but confirming the above carbon dating.[2]

Flow System

2011-07-25 11-33-33 Switzerland Graubünden Rhine Gorge 4vl
Rhein Gorge Ruinaulta with railway bridge

After the slide most of the water escaped through the upper section of the debris. There are several examples of rivers disappearing in the Alps and also in Scotland. The lakes in the debris area still behave in this way such as Caumasee. The Ilanz lake existed some 1000 to 2000 years before the water cut through the debris, creating the Gorge.


Flims Plattform
Viewing platform at Conn near Flims
  • The place Dutjen above Valendas is opposite and gives a good overview.
  • The aerial cableway from Flims onto Cassonsgrat takes you to the tear-off edge of the landslide. There is various hikes to this ridge as well. One route uses the ascent via Val Bargis, probably the nicest ascent although you cannot see the rockslide area before reaching the top.[3]
  • The railway line of the Rhätische Bahn crosses Ruinaulta close to river Rhine. Except for access to the railway stations there is no roads into this area and no parking. A footpath goes for two thirds of the gorge, the last bit is being built in 2010/2011. Connections lead out of the gorge.
  • In Conn on the debris there is a viewing platform in the shape of a common swift, overlooking Ruinaulta. Walking there you will encounter a little artificial stream that ancient farmers built to get water to some fields in the area as there is no natural surface water.
  • There is river rafting on the Rhine.


  1. ^ [1] Archived 2011-07-06 at the Wayback Machine A.v.Poschinger, Angewandte Geologie, Vol. 11/2, 2006 english version
  2. ^ [2] A.v.Poschinger, Angewandte Geologie, Vol. 11/2, German version including carbon dating of wood in debris
  3. ^ Hiking Switzerland Graubünden Fil de Cassons Archived 2011-06-07 at the Wayback Machine


  • Albert Heim: Der alte Bergsturz von Flims 18. Jahrbuch des Schweizer Alpenklub 1882-1883 p. 295-309
  • [BERGSTURZ-GEBIETE DER SCHWEIZ, PROFILE] [Kartenmaterial] / Alb.Heim. - Zürich: Kunstanstalt J.C.Müller, Abt.Kartogr.Hofer, 191.. [000450082]
  • G. Hartung: Das alte Bergsturzgebiet von Flims, Zeitschrift der Gesellschaft für Erdkunde. Berlin (19) 1884
  • Dr. Julius Weber: Klubführer; Geologische Wanderungen durch die Schweiz (II), 1913 S. 162-173
  • Seesedimente auf der Flimser Bergsturzmasse: ein neuer Ansatz zur Datierung der grössten Massenbewegung der Alpen (~ 9490 - 9460 cal. y BP): Flims/Laax, Graubünden, Schweiz / Gaudenz Deplazes. Zürich; 2005.. 140 S.: Ill. + 4 Falttaf.. [005083370]
  • Emil Kirchen: Wenn der Berg stürzt: das Bergsturzbegiet zwischen Chur und Ilanz - Chur [etc.]: Terra Grischuna, cop. 1993. [000943845] ISBN 3-7298-1087-1
  • Zur Hydrogeologie des Bergsturzgebietes im Raum Flims / Y. P. Bonanomi.. . [et al.]. - Bern: Landeshydrologie und -geologie, cop. 1994. (Geologische Berichte / Landeshydrologie und -geologie; Nr. 17) [000955866]
  • Carl Bieler: Als der Berg runterkam, 2006, Migros-Magazin

External links


Caumasee (Romansh: Lag la Cauma or Lai da Cauma) is a lake near Flims, in the Grisons, Switzerland. It is one of the lakes on the Flims Rockslide deposits. The lake is fed from underground sources. Its surface area is 10.3194 ha.

The level of the lake varies by approximately 4 to 5 meters along with the varying underground water flow during the year, hence reaches its minimum by the end of April when snow melting in the mountains increases. A maximum level is reached by mid July but may be topped in August even after previous falling due to summer rain. The very western bay never freezes in winter, probably showing a maximum water flow in this area.

When the lake is at a low level, with a small volume of water, it warms up sooner than most lakes in the region, so people can be seen starting to swim the lake in April while bigger lakes even in lower areas of Switzerland remain rather cool. Water temperature in summer is at an average 21 Celsius, with a maximum around 24 Celsius.

The lake is in a huge forest that was allowed to remain on the agriculturally useless debris area of the biggest prehistoric rockslide in the Alps and can only be reached by a footpath (wheelchair accessible), possibly using a funicular built in 1939, refurbished in 1988 on its original tracks (running May to October only). The walk from the edge of town to the funicular takes about 10 minutes.

Crap Sogn Gion

Crap Sogn Gion (meaning Saint John's stone in Romansh) is a mountain (2,263 m) and cable car station (2,216 m) located near Flims in the Swiss canton of Graubünden. Regarding the definition used in the Alps by the Swiss Alpine Club it cannot be called a mountain (nor even a peak with a strict definition) but only a location at the end of a ridge descending from the Vorab in the Glarus Alps.

As the location has no distinctive peak nor sudden drops in its gentle sides, it is absolutely not an impressive mountain but even more a very appropriate place to run a skiing resort. Comparing to other skiing resorts in Switzerland the missing neighbouring mountains to the south - which is the location of the giant prehistoric Flims Rockslide – make it even more exposed to the sun even at the sun's lowest orbit in deep winter.

A very small hut of the Ski Club Flims was the first building on Crap Sogn Gion, still standing there although hardly noticed. From 1962 the area was accessible by platter lift, followed 1967 by the then biggest aerial cable car with cabins to hold as much as 125 passengers, which is still in use today along with several modernised chairlifts.

A more recent aerial cable car was built to Crap Masegn, from where another gondola lift leads to the glacier at Vorab, which made the ski resort a safe one in regards of snow even in winters of poor snowfall.

For a walk in summer you may find Crap Sogn Gion on Swisstopo Map 1194, Flims, in the 1:25'000 scale. National Maps of Switzerland are a set of official map series designed, edited and distributed by Swisstopo, the Swiss Federal Office of Topography.


Crestasee (Romansh: Lag la Cresta) is a small lake shared by the municipalities of Flims and Trin in the Grisons, Switzerland. From 1892 a guest house on its northern end served as pension and still is a restaurant today in its original state.

There is no tributary to the lake and whilst walking along its shores you may be surprised by finding the lake both sides of you, realizing, that the holes between the rocks lying around the lake are filled with water. The rough character of the whole area derives from being a debris area of the gigantic Flims Rockslide, where waters flow underground until feeding lakes at certain spots such as Crestasee, Caumasee or Lag Prau Pulté.

Less than 100 yards (91 m) from its northern end a gorge called "Felsbachschlucht" is formed by river Flem, coming from Flims, whose Romansh name is Flem anyway. The waters from the lake and river are independent, and of course the river had only some 10 000 years to create the gorge as this is the age of the rockslide.

The water from the lake forms a small stream and enters the Flem river after a very short run, not called a special name for its short length.

In summer it is well known for swimming and offers facilities (such as a kiosk, toilets, changing room, boats and SUP's to rent) to enjoy this. An entrance charge will be collected by an employee of the restaurant, walking around the lake once or twice a day. Crestasee can be reached from Flims via the Felsbachschlucht gorge or wide forest paths, as well as from Trin Mulin or the public post car stop Felsbach/Crestasee on the main road, to where it is connected by a nice and short path. Motorists have to walk a similar distance to the lake, as there is no access to the lake by car and signposted parking is well off the lake.

A nice forest walk leads to Conn, to see the Ruinaulta gorge formed by the Rhine, still within the same huge rockslide debris area, or to the Lag la Cauma.

Fil de Cassons

Fil de Cassons (also known as Cassonsgrat) is a mountain in the Glarus Alps, located near Flims in the canton of Graubünden, Switzerland.

The southern face is referred to as "Flimserstein", dominating the appearance of the town of Flims. In its east lies Bargis from where a valley leads to its north face, while to its western face the sliding surface tears off of the biggest visible landslide in the world, Flims Rockslide. Piz Dolf is lying to the north across the Bargis valley, and to its west Piz Segnas, both showing the tectonic line of the Glarus thrust in its upper part, a now UNESCO world heritage.

The easiest access to Fil de Cassons is an aerial cableway from Flims to this ridge, that actually allows also walks and an alpine experience from the cablecar for people that would not dare to walk a steep mountain path. Walking on top you will easily identify the tectonic line under your feet, as rocks turn from greenish to bright light grey on top of the wide ridge.

For hikers aiming for more than a walk, several routes reach the high plateau and the very wide ridge, among them a historic Via Ferrata called Pinut. One hiking route uses the ascent via Val Bargis and Scala Mola, the path that the cows are being sent up to graze in summer. If you stay at the base of the valley of Bargis, you will hike on a path leading more or less around Fil de Cassons from east to northwest before reaching its top.Being a ridge, there is very often hardly snow, allowing walks even in winter along at least one mile on Fil de Cassons.


Flims (Romansh: Flem) is a municipality in the Imboden Region in the Swiss canton of Graubünden. The town of Flims is dominated by the Flimserstein which one can see from almost anywhere in the area.

Flims consists of the village of Flims (called Flims Dorf) and the hamlets of Fidaz and Scheia as well as Flims-Waldhaus, the initial birthplace of tourism in Flims, where most of the hotels were built before and after around 1900.

Il spir

Il Spir is a viewing platform at Conn, a location near Flims in the canton of Graubünden in Switzerland.

The platform overlooking the Ruinaulta gorge of the Vorderrhein river was designed by Corinna Menn and opened in 2006. It allows a good view of the gorge and the river lying some 400 meters below. While it took 40,000,000 years to develop the Grand Canyon in Arizona, the young Rhine dug this gorge within 10,000 years. This is the age of Flims Rockslide, which covered the original Rhine valley with its debris. The river is still running through debris, meaning it has not reached the former valley yet. Flims Rockslide is the biggest rockslide whose effects are still visible in the world.

The platform has the shape of a common swift, a common sight at the southern faces of the gorge, and consists of one single pylon, anchored by wire rope.

There is no access to near the platform for individual traffic nor public transport and the only means of transport is a privately rented carriage. Walking from Flims-Waldhaus, one can reach the platform in less than an hour, which is a slightly shorter distance as to Trin-Mulin, both villages being on the main road and offering an hourly service by the Swiss postbus system. The multi-day trekking route "Senda Sursilvana" passes Conn as well.


The term landslide or less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

List of landslides

This list of landslides is a list of notable landslides and mudflows divided into sections by date and type. This list is very incomplete as there is no central catalogue for landslides, although some for individual countries/areas do exist. Volumes of landslides are recorded in the scientific literature using cubic kilometres (km3) for the largest and millions of cubic metres (normally given the non-standard shortening of MCM) for most events.


The Rhine (Latin: Rhenus, Romansh: Rein, German: Rhein, French: le Rhin, Italian: Reno, Dutch: Rijn) is one of the major European rivers, which has its sources in Switzerland and flows in a mostly northerly direction through Germany and the Netherlands, emptying into the North Sea. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps, forms part of the Swiss-Liechtenstein, Swiss-Austrian, Swiss-German and then the Franco-German border, then flows through the German Rhineland and the Netherlands and eventually empties into the North Sea.

The largest city on the Rhine is Cologne, Germany, with a population of more than 1,050,000 people. It is the second-longest river in Central and Western Europe (after the Danube), at about 1,230 km (760 mi), with an average discharge of about 2,900 m3/s (100,000 cu ft/s).

The Rhine and the Danube formed most of the northern inland frontier of the Roman Empire and, since those days, the Rhine has been a vital and navigable waterway carrying trade and goods deep inland.

Its importance as a waterway in the Holy Roman Empire is supported by the many castles and fortifications built along it. In the modern era, it has become a symbol of German nationalism.

Among the biggest and most important cities on the Rhine are Cologne, Düsseldorf, Rotterdam, Strasbourg and Basel.


Ruinaulta is a canyon created by the Anterior Rhine between Ilanz/Glion and Reichenau in the debris of the Flims Rockslide just upstream of its confluence with the Posterior Rhine at Reichenau in the Grisons, eastern Switzerland. It is sometimes known as the Rhine Gorge, or sometimes rather ironically called Swiss Grand Canyon. Protected by cliffs several hundred metres high, the area is forested and a haven for wildlife. It is a popular location for rafting.The gorge is largely inaccessible by road, but is traversed by the Disentis to Chur line of the Rhaetian Railway. It is accessible from the Valendas-Sagogn, Versam-Safien and Trin stations that lie within the gorge.

Surselva Region

Surselva Region is one of the eleven administrative districts in the canton of Graubünden in Switzerland. It was created on 1 January 2017 as part of a reorganization of the canton.Surselva Region has an area of 1,373.56 square kilometers (530.33 sq mi), with a population of 21,483 as of 31 December 2018..

It corresponds exactly to its predecessor, Surselva District, but the former subdistricts (Kreise) of Disentis, Ilanz, Lumnezia/Lugnez, Ruis and Safien have been abandoned.

Surselva ("above the forest") is the name of the valley of the Anterior Rhine in the local (Sursilvan) dialect of Romansh. The eponymous forest is that of the Flims rockslide; the region "below the forest" is Sutselva, where the Sutsilvan dialect used to be spoken.


Sursilvan (pronounced [sursilˈvaːn] (listen); also romontsch sursilvan [roˈmɔntʃ sursilˈvaːn]) is a group of dialects of the Romansh language spoken in the Swiss district of Surselva. It is the most widely spoken variety of Romansh with 17,897 people within the Surselva District (54.8%) naming Romansh as a habitually spoken language in the Swiss census of 2000. The most closely related variety is Sutsilvan, which is spoken in the area located to the east of the district.

The name of the dialect and the Surselva District is derived from sur 'above' and selva 'forest', with the forest in question being the Uaul Grond in the area affected by the Flims Rockslide. The word selva itself has fallen out of use in modern Sursilvan, with the most common word for forest being uaul , an Old High German loanword. Selva is only used for in a few more recent terms such as selvicultura 'forestry', selvicultur 'forest officer', or cavrer selvadi 'Long-eared owl'.

Swiss Alps

The Alpine region of Switzerland, conventionally referred to as the Swiss Alps (German: Schweizer Alpen, French: Alpes suisses, Italian: Alpi svizzere, Romansh: Alps svizras), represents a major natural feature of the country and is, along with the Swiss Plateau and the Swiss portion of the Jura Mountains, one of its three main physiographic regions. The Swiss Alps extend over both the Western Alps and the Eastern Alps, encompassing an area sometimes called Central Alps. While the northern ranges from the Bernese Alps to the Appenzell Alps are entirely in Switzerland, the southern ranges from the Mont Blanc massif to the Bernina massif are shared with other countries such as France, Italy, Austria and Liechtenstein.

The Swiss Alps comprise almost all the highest mountains of the Alps, such as Dufourspitze (4,634 m), the Dom (4,545 m), the Liskamm (4,527 m), the Weisshorn (4,506 m) and the Matterhorn (4,478 m). The other following major summits can be found in this list of mountains of Switzerland.

Since the Middle Ages, transit across the Alps played an important role in history. The region north of St Gotthard Pass became the nucleus of the Swiss Confederacy in the early 14th century.


The Vorderrhein (German; English: Anterior Rhine; in the local Sursilvan language: Rein Anteriur) is one of the two sources of the Rhine. Its catchment area of 1,512 square kilometres (584 square miles) is located predominantly in the canton of Graubünden (Switzerland). The Vorderrhein is about 76 kilometres (47 mi) long, thus more than 5% longer than the Hinterrhein/Rein Posteriur (each measured to the farthest source). The Vorderrhein, however, has an average water flow of 53.8 m3/s (1,900 cu ft/s), which is less than the flow of the Hinterrhein. According to the Atlas of Switzerland of the Swiss Federal Office of Topography, the source of the Vorderrhein– and the Rhine –is located north of the Rein da Tuma and Lake Toma.

Vorderrhein was also the name of a judicial district that was created in 1851 with the reorganization of the judiciary of Graubünden. In 2001, it was annexed by the District Surselva.

The largest communities along the Vorderrhein are Disentis and Ilanz.


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