1) Arcouzan

The Arcouzan Glacier is the most easterly glacier in the Pyrenees, as well as being the only one located in a Pyrenean massif that does not reach 3,000 m in altitude. The highest point of the massif is the summit of Mont Valier itself, at 2,838m.

Although its regression is evident, it has not lost its glacial condition. Its reduced extension of 1.5 ha represents a relict glacial vestige secluded in a watercourse, at an average altitude of 2,450 m. It is one of the lowest glacier-covered peaks in the Pyrenees.

The snow supply provided by various corridors and the scarce solar radiation it receives, despite its eastern orientation, have allowed it to remain active to the present day. It is a glacier that is particularly reactive to years of abundant snowfall. In unfavourable summers, the loss of thickness of this glacier currently averages 2 m/year, significantly lower than that of other Pyrenean glaciers. Its left flank, the furthest from the walls that protect it, and the least efficiently fed sector, shows the highest rate of regression, losing more than half of its width, which during the Little Ice Age was over 175 m.

The most accessible observation point on the Arcouzan glacier is on the slopes near the summit of Mont Valier. The normal ascent route starts at 960 m, which makes an overnight stay at the Estagnous hut at 2,245 m advisable.