Lac de Montcineyre
| Lac de Montcineyre | ||
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| Geographical location | Commune of Compains , Puy-de-Dôme department , Auvergne-Rhône-Alpes , France | |
| Tributaries | unnamed | |
| Drain | no recognizable | |
| Data | ||
| Coordinates | 45 ° 27 '35 " N , 2 ° 53' 47" E | |
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| Altitude above sea level | 1182 m | |
| surface | 39 ha | |
| length | 800 m | |
| width | 550 m | |
| Maximum depth | 22 m | |
The Lac de Montcineyre is a lake of volcanic origin in the French Massif Central . It is located in the municipality of Compains in the Puy-de-Dôme department ( Auvergne-Rhône-Alpes region ).
etymology
The lake is named after the Puy de Montcineyre volcano of the same name . The French. The noun Mont means mountain. The Occitan or Auvergnatian word cineyre comes from the Latin masculine noun cinis , genitive cineris meaning ashes . The Lac Montcineyre is therefore the lake of the Aschenberg .
geology
When the Puy de Montcineyre erupted 7635 ± 115 years ago BP (calibrated age) at the beginning of the Atlantic , a cinder cone was formed which blocked the path of a small stream and thereby gradually dammed the lake. The lake thus comes to rest on the ejecta of the Puy de Montcineyre, which in turn covers ash from Lac Pavin .
geography
The Lac de Montcineyre is 3 kilometers northwest of Compains (as the crow flies) and is on the border of two large physiographic regions - the Monts Dore in the northwest and the Massif des Cézallier in the southeast. Immediately to the west, the watershed runs between the catchment area of the Loire , to which the lake belongs, and the Garonne . Its altitude is 1182 meters. Its surface is 39 hectares and its maximum water depth is 22 meters. The lake measures around 800 meters in north-south direction and 550 meters in east-west direction. A sickle-shaped extension extends the lake by another 250 meters to the northeast. A small tributary is on the northwest side. The Puy de Montcineyre builds up directly in the southeast of the natural reservoir .
geomorphology
The profile of the lake is funnel-shaped with relatively steep sides, with the eastern shore having a significantly steeper slope due to the volcanic cone. The bottom of the lake is not flat, but inclined towards the volcano. It has two circular depressions as the deepest points, which possibly indicate two small hidden maars .
Lake sediments
On the lake floor 3 to 4 meters of fine-grained sediment has accumulated, which has a surface area of 19 hectares and mainly covers the two depressions. The sediments are rich in organic matter and often contain gas. They are also layered and reveal two clear seismic reflection reflectors R 1 and R 2 . A mass flow could be identified on the northeastern edge in about 10 meters water depth. In the southern section, at a depth of 15 meters, Gyttja lies above the underground on the west side, which kinks towards the depression.
Catchment area
The unsymmetrical catchment area of the lake is relatively small at 1.5 square kilometers (catchment area / lake ratio = 3.85); the autogenous Holocene sediments are therefore very rich in organic matter. The maximum extension in east-west direction is just under 2 kilometers and in north-south direction around 1.5 kilometers. The highest point at 1333 meters is on the northwest corner, the lowest at 1182 meters at the northeast end of the lake. The slopes of the volcanic building in the east are quite steep at 26.6 °, but the slopes on the west side are much flatter at 5.7 to 16.7 °. The catchment area consists in roughly equal proportions of beech forest , meadows and coniferous forest ( Pinus sp. ) That was only planted towards the end of the 1960s . There are also two small swamp areas on the northwest corner of the lake . The beech forest covers the slopes of the volcanic building and the southwest side of the lake. The meadows are mainly found on the west side. They were used as summer pastures in the 11th and 12th centuries, comb-like contours in the terrain (auvergnati tras ) still reveal the former shepherds' shelters.
earthquake
A sediment profile in the northern part of the lake was able to pass through reflector R 1 under 8 meters of water cover at a depth of 65 centimeters and determine an age of Anno 1320 for it. Since it is directly in contact with the mass flow, the latter has the same age. The Outbound from the east bank of mass flow can as the cause of an earthquake of Mercallistärke accept VI to VII. A similar process in Lac Pavin results in AD 1300 there.
After the earthquake, the terrigenous intake (with increased soil and vegetation debris) and the sedimentation rate increased dramatically. Only on the last 15 centimeters did the sedimentation slow down again and was then dominated by organic input (mainly algae residues).
The earthquake around 1300 cannot be assigned to any historically known event. However, earthquakes are not uncommon in the area around the Chaîne des Puys , as demonstrated, for example, by the destructive earthquake with magnitude M w = 6.1 in 1490, which caused severe damage in Clermont-Ferrand and Riom .
Individual evidence
- ^ Gewelt, M. and Juvigné, E .: Téphrochronologie du Tardiglaciaire et de l'Holocène dans le Cantal, le Cézallier et les Monts Dore (Massif Central, France): résultats nouveaux et synthèse . In: Bulletin de l'Association française pour l'étude du quaternaire . tape 25 , 1988, pp. 25-34 .
- ↑ Emmanuel Chapron et al .: New Evidence of Holocene Mass Wasting Events in Recent Volcanic Lakes from the French Massif Central (Lakes Pavin, Montcineyre and Chauvet) and Implications for Natural Hazards . In: 5th International Symposium on Submarine Mass Movements and Their Consequences, Oct 2011 . tape 31 . Kyoto, Japan 2012, p. 255-264 .
- ↑ Leo Chassiot: Forçages naturels et anthropiques sur la sédimentation holocène en domaine lacustre. Application aux lacs d'Auvergne et aux réservoirs des bassins versants de la Loire et d'Adour Garonne (doctoral thesis) . Université d'Orléans 2015.