Geologists say the rockslides around the Grindelwald glacier are a good illustration of how global warming leads to significant shifts in mountain landscapes.
This view is drawn from the perspective of someone standing on the glacier. The Eiger Mountain is on the left of the sketch (W) and the Mettenberg on the right (E). Slow glacial melt over many years meant the sides of the canyon the glacier once filled lost support. The rock face on the west side of the canyon was normally additionally stabilized by ice that filled the natural small cracks in the rock.
But as that ice has melted, water accumulated in the cracks, creating immense pressure. Glaciologist Hans Rudolf Kreusen says a thin column of water ten meters high can produce about one ton of pressure per square centimeter. Last summer, about a half a million cubic meters broke off from the rock face all at once and fell into the canyon below. About two million cubic meters is still sliding slowly down the rock, and is expected to fall in the future.
On the east side of the canyon, the retreating glacier left behind moraine, the jumble of unconsolidated rock at every glacier's edge. For years the moraine was stable enough to support a hiking trail and small tourist hut, but in 2005 the moraine gave way and half the hut broke off over the canyon. Why then? Geologists suspect that 'dead ice' may have played a role in that slide. Dead ice refers to ice that once was connected to a glacier, but was left stranded as the glacier retreated. It usually remains deep in the earth, and in this case may have finally warmed enough that by 2005 could no longer support the ground where the hut stood.
A new hut, the Bäregg, opened in 2006, and was mobbed with tourists wanting to see massive rocks fall from the canyon's opposite wall.
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