ナンシーシュルクルースの湖・トップ18

Beautiful hidden lake on the outskirts of Taninges

Swimming break possible!

Sculpture that can be discovered along the Giffre as far as Morillon

Wild lake, silent

Wonderfully located in a protected valley, a wonderful hiking destination for a rest, in summer with a hut that is open all day, otherwise only on weekends or not at all.

Lake Flaine is located at the bottom of a valley over-excavated by a local glacier which descended from the summit of the lapiaz zone of the Platé desert (Tête lawn (2475 m) and Grandes platières (2480 m)) during the great glaciations. At its western end, it is blocked by the rocky threshold of the Col de Cou (1501 m). From a geological point of view, this depression is dug in limestone from the Urgonian (130 to 112 million years) and the Neocomian (145 to 130 million) which is very easily attacked by water and which therefore cannot hold her back. The bottom is however covered with a thick layer of silt that can reach several tens of meters which ensures its watertightness7. During the last retreat of the glacier from the basin, almost 12,000 years ago, the lake was 20 meters deeper and occupied the entire bottom of the basin over a length of 1200 m but it gradually shrank that the losses became more active and accelerated its evacuation. The result is a long plain slowly tilting 2% towards the west where the lake takes refuge in its low waters6. Currently, the lake is fed by four small streams, three of which are permanent. Two come from the Col de Cou while the third comes from the south and circulates under the scree. The main one follows the valley, it crosses the Flaine ski resort and its wastewater treatment plant and has a very variable flow rate: it can be dry but can also flow 300 l/s6. The surface area of the lake fluctuates accordingly and is only 1.5 ha and 0.8 m deep during low water in autumn and winter. However, it does not pass below this limit because its main outlet is not at the lowest point, but on its southern bank, in a scree. The flood period occurs when the snow melts to reach a size of 12 ha for a depth of 10.5 m, values reached in 1985-86 around June 1st. This value, however, seems higher than in previous decades since the water then surrounds the alpine chalets on the lake plain and the fir trees have their trunks in the water for several weeks, which represents conditions where they do not should not be able to develop. The cause of the increase in spring floods is attributed to the creation of the Flaine resort in the 1960s which led to waterproofing of the soil (parking lots, roads, sealing of lapiaz for ski slopes, etc.) as well as the capture of additional water from Lake Vernant8. Another consequence is that the bed of the Flaine stream has sunk several meters as it enters the lake plain6. During periods of high water, water flows through two additional temporary outlets located on the north side of the lake and forming funnels 2 to 3 m in diameter7. Water characteristics A surface temperature of 13.5° was recorded on May 26, 1986. In winter, the lake can also freeze over almost its entire depth. A measurement carried out during periods of high water revealed that its pH is relatively alkaline (9.08) for relatively low mineralization (TH = 4.46 °f mainly due to 17.2 mg/l of calcium). Lined by fine gray-beige silt, the lake is quite turbid and has a transparency of only around 1 m. Bacteriologically contaminated, around 1990 it was in an advanced state of eutrophication due to the lack of performance of the wastewater treatment plant6. The lake is regularly stocked with rainbow trout and brown trout9.

Lake Bénit is located at an altitude of 1,452 meters, on the northern slope (ubac) of the Bargy chain, in the Bornes1 massif. It is dominated to the south by the limestone wall of the Bargy chain from where the scree of the Col d'Encrenaz cirque spills out and delimits the south-west shore of the lake. The northwest bank corresponds to the slope of the old glacial basin while the east bank opens onto the valley of the Lac Bénit stream. In 1988, Father Arsène Bourgeaux, ethnographer, in a publication dedicated to the parish, indicated that the lake, “for the inhabitants of the Mont is considered as a sort of founding place where the identity of a population originates” 7. The lake was the subject of processions by the populations of Marnaz and Mont-Saxonnex, on Saint Claude's Day, in order to protect the villages from flooding. The lake benefited from developments in the early 1960s, notably with the raising of the lake level, which made it possible to double its surface area7. The inauguration took place on July 11, 19657. A mass was improvised by priest Claude Scherantz. Lake Bénit is the subject of many legends. One of them relates that the fairies came to bathe there and were at the origin of the production of butter and tomme in the town. A second legend says that an episcopal ring is found in the lake9. Following a deadly avalanche, the bishop of the diocese is said to have gone “in a grand procession” to bless the lake and to have thrown “his episcopal ring into the waves asking heaven that such a catastrophe never happens again”9. Another version says that the object was so heavy that it fell into the lake at the time of the blessing9. According to this legend, an avalanche emptied the lake and flooded Marnaz below4. Finally Alphonse Favre (en) reports that “this lake is due to a collapse in which a fir forest disappeared. As for the time, it can only be established in a very doubtful manner, by the fact that an old man from the village of Brezon assured, around 1845, that this event had happened in his father's youth. »1

Passage offering a view of the lake and leading to the green needle from which we have a view of the whole valley.