Lac du Génépy

10 points of interest

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  Flora

  The lilium martagon

  In June to July when you leave the forest and set foot on the mountain pastures, you may find a large plant with purple flowers. The lilium martagon, a rare species, colonises the clearings of the forest boundary. It favours so-called mespophilic meadows that are neither too dry or too moist. This plant, once picked, was threatened. It is now out of danger but will require, like other species, much respect on your part.

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  Pastoralism

  Agricultural decline

  Ÿou will notice on both sides of the trail, towards the Randolière, numerous small cembro pines, established in the middle of the pastures. Whereas the entire slope was once grazed and mown, the gradual disappearance of small farm holdings and the change in practices have encouraged this forest species to recolonise the area. Over time, if agriculture were to disappear, it’s in the forest that you would find yourself. The loss of these pasture lands will lead to a decline in biodiversity.

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  Viewpoint

  Lakes of the Aussois dam

  Downhill behind you, you will be able to see the lakes of the Aussois dams. The Plan d’Amont is remarkable for its turquoise colour, fed only by the melting snows and clear streams. Downstream, the Vanoise glaciers feed the lake thanks to 19 km of underground tunnels originating from the Doron de Termignon. The water is loaded with glacial “flour”, fine mineral particles torn from the mountains. This is what gives the Plan d’Aval its grey, milky colour.

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  Fauna

  The common rock thrush

  This colourful bird did not escape from a garden centre. Despite spending its winter in Sub-Saharan Africa, the common rock thrush regularly inhabits the dry rocky and sunny slopes of our mountains to breed. While it can feed on small lizards and seeds or fruit, it gains most benefit from the abundance of various insects. At the end of summer, it will return to its wintering areas. The common rock thrush has been on the decline in France for several years with about 1,500 breeding pairs left only in France. It is a spectacle to see, so keep a keen eye.

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  Flora

  The Silene acaulis

  This cushion, punctuated by bright pink flowers, is not a moss. The silene acaulis is one of the champions of adapting to the worst. The cushion-like form allows it to reduce day-time and night-time temperature variations that can be significant at these altitudes. Moisture will also be trapped in this hairy, small-leaved stem. The ancient decomposed leaves of the silène acaulis contain nutrients that will allow it to grow and to bloom. A taproot in the cushion’s core will allow it to cling to the steepest terrain.

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  Flora

  Persicaria vivipara

  In the midst of the sand and rock, a stem loaded with small white flowers appears. The persicaria vivipara grows here. Some plants germinate and develop in the fruit while the latter is still attached to the stock plant. This phenomenon corresponds to vegetative viviparity. If you examine the persicaria vivipara, you will see small green bulbs attached to the stem. The fruits of the persicaria vivipara then begin to germinate on the plant. The seeds of the persicaria vivipara are a delicacy for the rock ptarmigan.

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  Geology

  Snowy paving

  Look around you for flat, damp areas without vegetation. Ÿou are bound to notice that the rock slabs seem to have been sorted and patiently arranged, one against the other. Man is not responsible for this geometric pattern. Here, the alternating freezing and thawing cycles and the weight of the snow encourage the transport of stones and their alignment to create what we call snowy paving. In other cases, these phenomena may create polygonal grounds or stone circles.

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  Geology

  The filling of wetlands

  As you descend from the lake, you will notice the grassy and flat stretches of terrain. The ancient glacier has gouged out depressions in the bedrock. When the ice retreated, these areas became lakes. Just like the Lac du Génépy, alluvium has filled these depressions, the hygrophilous vegetation then colonised these wetlands. Some of these areas then dried up to become small grassy plateaus amid the ´rocky ground´.

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  Flora

  The dwarf willow

  Perhaps you have unintentionally trampled over its small, green and shiny oval leaves? Like Gargantua, you were walking over a forest! The dwarf willow (Salix herbacea) is the smallest tree in the world. Like other willows, its flowers will come together in catkins and cover the rocks with a fine cottony layer in July and August. The male and female flowers are on separate plants.

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  Geology

  The Lac du Génépy and its moraine

  If you think you will discover a clear expanse of water when you arrive at the lake, you will be surprised. The Lac du Génépy is a glacial lake. At the end of the little ice age (1550-1850) the Labby glacier left a moraine on the right bank of the lake. A moraine is an accumulation of stones transported along the front of the glacier and left in place during its retreat. The glacier gouges out the rock in front of the moraine. The glacial meltwater occurs in this basin, creating the Lac du Génépy. The very fine mineral particles that you can touch on the shores of the lake fill it gradually and give it its milky colour.