The enormous avalanche that overwhelmed the village of La Thuile between the 16th and 17th centuries was terrible, when the rise in temperatures and the consequent melting of the ice caused the Ruitor glacier basin to overflow.
Following this tragedy, the surviving population decided to go in procession to Lake Rutor to ask for divine protection, also carrying the relics of San Grato; furthermore, following a vision by a local inhabitant, it was decided to build a chapel here dedicated not only to San Grato, but also to Santa Margherita, invoked against the disruptive force of avalanches and landslides.
For over two centuries the populations of La Thuile, Pré-St-Didier, Morgex, La Salle and Derby went in devout procession every year to the Rutor. In 1937 the solemn blessing of the new chapel of San Grato and Santa Margherita took place, located on the rocky promontory overlooking the lake; the first chapel of 1607, however, stood near the lake in fulfillment of a vow made by the hunter Pantaléon Dottin, who had an apparition on the banks of the lake itself.

Procession: first Sunday of September.

From the car park at the bar in La Joux, take the Alta Via 2 route, AV2. Go past the crossroads with the itineraries that lead to the three waterfalls on the Ruitor, and when you come to another crossroad, continue along AV2, ignoring route 8 on the right, and head for the lakes of Bella Comba. After a section on level ground at Alpe Glacier and the lakes of the same name, the path steeply gains altitude, climbing to the pasture of Ruitor and lastly to the Deffeyes refuge.