Members of the ESP team recently enjoyed a jaw-dropping hike along the base of the North Face, or ‘Nordwand’, of the Eiger whilst on holiday in the Bernese Oberland region of Switzerland. The Eiger is a 3,967-metre (13,015 ft) mountain of the Bernese Alps, overlooking Grindelwald and Lauterbrunnen in the Bernese Oberland of Switzerland, just north of the main watershed and border with Valais. It is the easternmost peak of a ridge crest that extends across the Mönch to the Jungfrau at 4,158 m (13,642 ft), constituting one of the most emblematic sights of the Swiss Alps. While the northern side of the mountain rises more than 3,000 m (10,000 ft) above the two valleys of Grindelwald and Lauterbrunnen, the southern side faces the large glaciers of the Jungfrau-Aletsch area, the most glaciated region in the Alps. The most notable feature of the Eiger is its nearly 1,800-metre-high (5,900 ft) north face of rock and ice, named Eiger-Nordwand, Eigerwand or just Nordwand, which is the biggest north face in the Alps.
Although the summit of the Eiger can be reached by experienced climbers only, a more beginner-friendly hiking trail tracks along the base of the North Face of the mountain offering breathtaking views of the surrounding valleys and an insight into the geology of the formidable mountain.
The trailhead at Eigergletscher station can be reached by the newly opened Eiger Express tricable gondola from Grindelwald.
Geology of the Eiger
The Eiger does not properly form part of the main chain of the Bernese Alps, which borders the canton of Valais and forms the watershed between the Rhine and the Rhône, but constitutes a huge limestone buttress, projecting from the crystalline basement of the Mönch across the Eigerjoch.
In their paper “How to build the Eiger: Surface expression of litho-tectonic preconditioning” Mair, Lechmann and Schlunegger (2017) discuss their use of 3D geological modelling utilising older geological mapping of the area combined with newer structural data, cross-sections and geological data from the Jungfraubahn railway tunnel that travels through the Eiger mountain.
They conclude that the thrust contact between two stacks, which comprise a foliated basement and cover rocks, are responsible for the shape and overall architecture of the Eiger and its famous north face. The high-resolution 3D structural model paired with petrological data shows that second-order, horizontally aligned morphological steps in the north face are related to the foliation within the bedrock. We suspect the inherited fabric significantly modified the susceptibility to erosion mechanisms which in turn further amplified the morphological differences (expressed in e.g. terrain roughness or slope).
The changing face of the Eiger
Extreme weather conditions and the effects of climate change are acutely felt in the region and the surrounding Alpine area. Whilst small-scale avalanches and rockfalls occur regularly on the mountain in 2006 over 700,000m3 of material fell from the east face raising concerns over the effects of warmer temperatures and more extreme occurrences of freeze-thaw weathering on the steep faces.
Annual monitoring data from the Swiss Glacial Monitoring Network also highlights the dramatic retreat of the Lower Grindelwald Glacier, indicating that the current average retreat rate is approximately 20m per year.
Down the mountain
The trail eventually winds into Alpiglen after a number of switchbacks and a quick cool off in a glacial waterfall! A smaller trail leads back to Grindelwald or you can catch the descending Jungfraubahn cogwheel train back through the Alpine meadows – complete with the quintessential Alpine cow herds!
Let us know if you have any recommendations for future trails/hikes/climbs with interesting geology in the region or further afield!
