Lac d'Ilay
Lac d'Ilay | ||
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the Lac d'Ilay from the northeast | ||
Geographical location | Jura , France | |
Places on the shore | Le Frasnois | |
Data | ||
Coordinates | 46 ° 37 '34 " N , 5 ° 53' 51" E | |
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Altitude above sea level | 774 m | |
surface | 0.72 km² | |
Maximum depth | 32 m |
The Lac d'Ilay , also called Lac de la Motte , is a lake in the French Jura , in the Jura department , around 14 km south of Champagnole in Franche-Comté . It lies at 774 m on the ground of the municipalities of Le Frasnois and La Chaux-du-Dombief and covers an area of around 0.7 km². The lake is 1.9 km long, a maximum of 400 m wide and has a small island (Île de la Motte). Its greatest depth is 32 m.
Lac d'Ilay lies in a depression on the Champagnole plateau in the region of the five lakes. During the high stages of the various ice ages , the basin was lined by the Jura glaciers with layers of marl and clay , so that a lake could arise despite the karstified subsoil. According to the general strike direction of the Jura chains in this area, the Lac d'Ilay is oriented towards the southwest-northeast. It is separated from the Lacs de Maclu to the east by a railing rib . The bank areas are flat and, especially along the eastern bank, surrounded by a swamp belt. In the east, the hollow is flanked by the wooded ridge of the Bois de Ban with the Pic de l'Aigle ( 993 m ), in the west by the height of Le Laisenet ( 823 m ).
The Lac d'Ilay is fed by a tributary from the Grand Maclu and some springs in the area of Le Frasnois. The discharge is first above ground in the south, then underground to the upper reaches of the Hérisson . According to calculations, the mean residence time of the lake water is around 10 to 13 months. Lake water is pumped out at two locations for the preparation of drinking water for Le Frasnois and the region around Lac de Chalain . The sea circulation takes place according to the dimictic type. In most winters, Lac d'Ilay freezes over completely because of its high position in a basin (formation of a cold air lake ).
The landscape around Lac d'Ilay is under nature protection. In the marshland around the lakes there are rare plant communities for the region, including the Schneidried (Cladium mariscus).
On the island of La Motte, St. Desiderius founded the Saint-Vincent priory in the 6th century. The monks made the area arable and thus laid the foundation for the development of hamlets and villages. The priory was destroyed in the 17th century.
Web links
- Information on Lac d'Ilay (French)
- Cinq Lacs Nature Reserve (French)