Col du Soufre

Imagine 20,000 years ago, Lyon, Chambéry and Grenoble are drowned in an ocean of ice. Corsica and Great Britain are no longer islands because the level of the oceans is 100 m lower, and our ancestors hunt ibex and the European bison around Marseilles. Here, ice more than 1,000 m thick crushes you. Over the previous 2 million years, the periods of advancement and glacial retreat alternate every 100,000 years to the rhythm of the changing climate.

The National Nature Reserve was created in 1990 and is managed by Vanoise National Park. Plan de Tueda National Nature Reserve is located downstream of Vanoise National Park in the municipality of Les Allues. It extends from Lake Tueda all the way to the Gébroulaz glacier, encompassing both riverbanks of the Doron des Allues: in total there are 1,100 protected hectares of outstanding natural scenery to explore (and respect)! You can find out all about the secrets of the reserve’s biodiversity and the Swiss pine and its forest through a free exhibition and a range of activities all year round. Your host at Vanoise National Park can also answer any questions about the park, forthcoming events and walks in the area if you’d like to extend your outing (you can book guided outings with the Park’s warden-instructors). There is also a shop, where you can pick up a little souvenir of the Park to take home with you! And if you still want to find out more, head to the nearby glaciological trail for a fuller understanding of the landscape and the valley’s history. In the summer only, there’s also a botany trail to enjoy and tours of the reserve are organised by the warden. The centre is located in the Nature Reserve, so please follow the regulations. Dogs are not allowed in the Reserve, and may only be taken around the lake on a lead. Open in the summer. Maison de la Réserve de Tueda - MottaretMeribel Mottaret - Lac de Tuéda73550 Les Allues Tel.: +33 (0)4 79 01 04 75 www.vanoise-parcnational.fr/free

La famille Perret exploite depuis 33 ans cet alpage communal en faisant pâturer son troupeau de vaches de races Tarentaise et Abondance, entre réserve naturelle et pistes de ski. Pour Robert Perret , « C’est la qualité de l’alpage qui fait 70% du travail. Plus on monte en altitude, plus l’herbe est courte et grasse, et plus le fromage est long à venir… et donc meilleur il est ! ».  Visite de la ferme sur demande. Téléphone :  06 09 88 17 01

The snow falls and then compacts by the successive accumulation of layers. It becomes névé when it moves from a density of 100g/l to 500g/l. Depending on the altitude and its exposure to the sun, the névé stops melting in summer. The accumulation of these successive névés causes the formation of ice due to compression. Its density is then 900 g / l. Under the effect of the slope and its own weight, the glacial tongue begins to slide. The crevice between the névé and the glacier is called the “bergschrund”.

Since its creation in 1990, the Plan de Tuéda Nature Reserve has focused its preservation work on the cembro pine forest and the black grouse. This bird is an arctic-alpine relict Its history is intertwined with that of the glaciers. During the last ice age, our galliform was pushed back to Southern Europe by the advancing glaciers and in their retreat, some chose to ascend in altitude while others went back up to Northern Europe. As a consequence, these populations were separated.

"The glaciers behave like very large ""planes"". In a period of advance, they tear blocks of rock out of the mountain and crush them. Depending on the hardness of the rocks, this erosion happens relatively quickly. There is therefore a “rock bar” downstream of each glacial plateau. The slopes that you’ve just passed between the plateau of Plan de Tuéda and that of the Fruit are a fine example of this."

The glacier deposits and moves all rock debris that it tears from the mountain to the rhythm of these advances and subsequent retreats. These mounds are called “lateral moraines” when they are deposited on the sides of the glacier and “frontal moraines” when they are on the former glacial front. Behind the rock bars and moraines, glacial lakes can form. They generally disappear as a result of the filling or splitting of the dykes created by the moraines.

Ÿou will find yourself on the last “rock bar” cleared by the Gébroulaz glacier. Towards 1730, the “Sarde map” (land registry of the kingdom of Piedmont-Sardinia) identifies the glacial threshold at the foot of this “rock bar”. This glacier is followed between 1907 and 1965 by the Eaux et Forêts (Forestry and Water), and from 1991 by the CNRS (French National Centre for Scientific Research). It is part of a network of 9 worldwide glaciers (5 Alpine, 2 Andean and 2 Antarctic) used for the long-term monitoring of glacial and meteorological data.

"There are 3 types of continental glaciers: the ""white"" glaciers, such as Gébroulaz, where the ice is visible year-round and flows along the slope. The ""black"" glaciers, such as the one in the Col du Grand Infernet, are covered with stones and continue to flow. And finally the ""fossil"" glaciers, which subsist only in the form of traces of pebbles that take a concentric form (small waves) and where the ice has disappeared completely. The latter are immobile. This is the case below the Col du Fruit in this valley!"

Wearing white camouflage was not invented by the Alpine troops. This discovery is to be attributed both to the mountain hare and another arctic-alpine relict, the rock ptarmigan (Lagopus mutus). This cousin of the black grouse trades its summer grey-brown plumage for an entirely white camouflage in winter. And as if this adaptation to the snowy environment were not enough, the bird has also evolved to have furry boots! Its entire claw up to the tip is feathered&hellip, you guessed it, in white.

"Whereas glacier advance is known during the ""Little Ice Age"" (1600-1850), their retreat in the 150 years that followed is no longer in doubt (example: surface of Gébroulaz in 1965: 420 ha and in 2009: 330 ha). Recent monitoring has given surprising results. The upper part of the glacier (above 3,100 m in altitude) has thickened by 20 metres! Explanation: the glacier passes through a rocky narrowing which compresses it laterally and causes it to swell artificially."

"The ""glaciers"" have greatly impressed the collective imagination of the Alps and their shrinking forms, in landscape terms, is nothing short of a crime of lèse-majesté. The Gébroulaz glacier is one of the best monitored in France, with certain measures such as topographical maps dating back as far as the twentieth century. The annual measurements, useful for understanding, do not however prevent the glacier from decreasing in surface and thickness, depositing lateral moraines as here in its central zone."

"In Vanoise, since the end of the ""Little Ice Age"" (around 1850), the glaciers have lost 50% of their total surface area. It is regretful to witness the disappearing glaciers, such as Coin, Goyard, Nants and those in the Fournache valley. The glaciers of the Dôme de la Vanoise total another 19.6 km², over the 40 km² a century and a half ago."