During the winter of 2008/09 three large ice caves were discovered under the tongue of Vadret da Morteratsch. They were formed by subglacial ablation caused by a stream underneath the glacier. Presently, guided tours into the caves are offered by Go vertical, Pontresina. Entering the caves does involve a certain risk from roof collapse. Glaciers online cannot quantify the frequency and indicate the most likely time of roof collapse events.
A large moulin forms the natural entrance to the central ice cave.
A ladder, temporarily installed by mountain guides, facilitates access to the central cave.
The air temperature in the caves is almost exactly 0°C.
Visitors attending a lecture on glaciology in the central cave.
Despite very low temperatures outside, water (several l/sec) is flowing through the caves.
On the right a candle illuminates part of the lower cave.
Ice debris from a roof collapse in the lower cave.
Visitors climb over some ice debris to reach the lower cave.
Lower end of the upper cave; visitors move towards the central cave.
Top end of upper cave; the meltwater stream emerges behind the group of people.
Ice debris from a partial roof collapse in the upper cave.
Air bubbles in basal ice; image width approximately 5 centimetres.
The caves can be considered a result of glacier recession since very little forward ice movement takes place at the rapidly thinning glacier tongue. Cavities, once formed, remain open for a long time due to the slow motion and lack of plastic deformation of the ice. Photos Jürg Alean, 20. February 2009
