|Karst cave. Ice cave
|A=1,220 m asl., L=24 m, VR=18 m, W=10 m, H=10 m.
|Grotte de la Glacière de Corrençon, 38250 Corrençon-en-Vercors, Tel: 04 76 95 81 75
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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|cave closed with a fence.
The Grotte de la Glacière de Corrençon (Ice Cave of Corrençon) is an ice cave of the cold trap type. This means, it is a vertical shaft with an entrance at the top. In winter the cold air, which is heavier than the warmer air inside the cave, is flowing into the cave. In summer the cold air inside the cave stays there, trapped, because it is heavier. This works like the open refrigerators in supermarkets. This trapped cold air makes the cave colder than other caves in the area, and as its temperature is around 0 °C, the dripping water freezes inside the cave, and there is ice. The ice stays all year, thats why the cave is called Glacière (Ice Cave).
The Grotte de la Glacière de Corrençon is located a little uphill, 1 km to the west of the village Corrençon-en-Vercors. There is no road to the cave, but it is easy to reach with a short walk. The cave is rather small, but the entrance is a vertical shaft. There is a wooden staircase which allows to reach the floor and see the ice inside the cave. There is also a plate which explains the formation of the ice.
For a long time the cave has been open to the public, but some years ago the entrance was closed by a fence and an iron bar gate. This was necessary to protect the visitors from rockfall and accidents. So it is possible to see the cave entrance with the cliff above, but not to enter.
The cave entrance is located at the foot of a cliff, at the bottom of a depression. From the much shallower opposite side the path enters the depression. This side is formed by debris. The cave formation is based on shear zone, several slickensides can be seen at the entrance. The overhanging cliff face above the entrance prevents snow inside the cave, so the ice is formed completely during the winter and spring, when the cave is a little colder than in summer and dripping water reaching the cave is freezing inside.
The ice is formng in winter and spring, when cold air is entering the cave, cooling it below zero. The replacemant of humid cave air (98%rel) with drier outside air causes evaportion, which also cools down the cave. During summer and fall the coolong effect stops, and the higher temperature of surrounding rock starts to rise the temperature inside the cave. A part of the ice melts. At the moment the yearl formation of new ice and the melting of ice are in an equilibrium. Otherwise the ice would either vanish or it would grow until it fills the cave completely.