The rocks are all calcareous, with large blocks of erratic granite.

The glaciere lies about 40 minutes from the Chalet of Montarquis, whence its local name of _La grand' Cave de Montarquis_.

Before reaching it, a spacious grotto presents itself, once the abode of coiners: this grotto is cold, but affords no ice, and near it M.Morin found a narrow fissure, leading into a circular vaulted chamber 15 feet in diameter, in which stood a solitary stalagmite of ice 15 feet high.
The entrance to the glaciere itself is elliptical in shape, 43 feet broad at the base, and the cave increases in size as it extends farther into the rock, the floor descending gently till a horizontal esplanade of ice is reached.

This esplanade was 66 feet by 30 at the time of Pictet's visit, deeper in the middle than at the sides, and mounting the rock at the farther side of the cave; there was a small stalagmite at one side, but that would seem to have been the only ornamentation displayed.

The temperature was 34 deg..7, a foot above the ice, and 58 deg.