The Arsine Lakes

With its disproportionately high spire, the Casset church never goes unnoticed. Its four-sided Comtois steeple was modelled on the collegiate church in Briançon. The church is listed as a Historic Monument and is placed under the protection of Saint Claude. In its present condition, it dates from the 18th century. The previous building was constructed prior to the 16th century. Inside, the eye is immediately attracted by the choir ogives, creating an intimate atmosphere, particularly since the unusually large spire does not suggest an interior of such a small size. The choir was rebuilt in 1716-1717, probably after the previous chapel burnt down. Traces from this period can be seen on the keystone. The wrought-iron choir gate has the inscription "HM 1717", a date that can also be seen in the apse, on the wrought iron railing of the impost of the axial window, and on the baptismal font.

The mountain streams relinquish their secrets to an attentive hiker. The master of this little world is a small brown, red and grey bird with a short tail and a pure white breast, separated from the darker abdomen by a light brown stripe. We can often see it in the air, flying close to the water to snap up insects. The dipper owes its name to its eating habits to find water larva, it dips its head into the water and grips the riverbed to walk against the current.

Rupicapra rupicapra, the mountain goat was not at first solely a creature of the mountains. The species is more attached to rocky escarpments and steep slopes than high altitude. But strong human pressure on chamois made them withdraw ever higher. Coveted as a hunting target, they have found refuge here in the Ecrins National Park.

The Petit Tabuc site is ideal for the golden eagle to nest. The golden eagle is amongst the protected species that are considered rare in Europe.  The size of the populations that have been registered in the Ecrins massif, bestow a strong responsibility on the Park for conservation of the species. Counting takes place regularly since 1985 along with monitoring of reproduction, causes of disturbance and mortality.

The eagle is the archetypal predator. Everything about it suggests strength and daring. Its appearance, of course, with its impressive expression highlighted by the prominent brow ridge, but above all its fearsome weapons: rapid flight, which can be adapted to even the most acrobatic situations, and sharp, powerful talons. Its keen eyesight helps it detect its prey, from the marmot to the young chamois, ptarmigans and hares. In winter, it often takes its food from the dead bodies of animals, helping towards the natural cleansing of nature.

Even though it is relatively common in some acidic marshland, the Arctic rush is nonetheless protected throughout the Rhône-Alpes and Provence-Alpes-Côte-d’Azur regions. It can be recognised because of its total absence of leaves and by the few blackish flowers in the upper third of the stalk. The flower tepals open at an obtuse angle and are a little shorter than the capsule.

At five in the morning in the month of May, at an altitude of over 2,000 m, the sun rises over the fields of blueberry, which appear above the patches of snow. All of a sudden, a hoarse, almost metallic cry cuts through the peaceful dawn atmosphere: the rock ptarmigan is in the midst of its nuptial parade. Originating from the Arctic tundra, the rock ptarmigan, sometimes called the snow partridge, was to be found all over Europe during the ice ages, before its living space was limited to the mountains. Even today, it finds the conditions it needs to survive. The national Alpine parks have a great responsibility in conserving this species. The inventory carried out by the Haute-Romanche nature unit in 2005 showed there was a large core group of birds on the site.

When the lake is frozen and the air temperature rises, the ice expands, provoking what is called the “song of the lake". The Lac Ouest is the last lake in the mountain range where it is still possible to see the fall of seracs (the front of the glacier) into the water, giving rise to this muffled noise.

Lake Arsine came to life in the 1950s after the Arsine glacier melted. Due to its rapid development, it was measured more accurately in 1969 and 1985, showing 800,000 m3 of water contained in a moraine that had been weakened by the ice inside it. Since it threatened to break, emergency work was undertaken the following spring to stop the rise in the level of the lake using a regulation channel dug across the frontal moraine. Almost 30 years later, the glacier site is still carefully monitored by Park employees. And the risk is now completely ruled out.

The Arsine glacier is contained in the hollow of a vast corrie facing north, encircled by high walls reaching an altitude of between 3,200 and 3,600 metres. This is a glacier that is mostly hidden, with the front, currently at an altitude of about 2,470 m, behind lakes. The lakes are held back by an impressive series of old moraines, formed during the Little Ice Age (between about 1550 and 1850). Due to its size and preserved state, the old moraines of Arsine are an exception in the western Alps. Usually such morainic fronts are found in small, high-altitude glaciers, resulting water running too weakly to sweep away the accumulation of pre-glacier deposits (for example, the Réou d’Arsine glacier). The melting and shrinking of the Arsine glacier posed problems in the 1980s concerning water retention and therefore safety. RTM teams carried out work to lower the level of the lakes, the size of which raised fears of a break in the moraine with the risk of flooding the village of Le Casset.