Karst – from Processes to Records
Marc Lütscher (Institut Suisse de spéléologie et karstologie ISSKA)
Stefanie Wirth (Centre d'hydrogéologie et de géothermie, Univ. de Neuchâtel)
With contributions from: Philipp Häuselmann (ISSKA), Pierre-Yves Jeannin (ISSKA), Judit Deák (Canton of Neuchâtel)
This excursion through the karst landscape of the Jura Mountains led us from our meeting point in Morges to our first stop, the spring of Malagne at the foot of the Jura Mountains. Here, we got an overview of the geology and the organization of the karst drainage system in this southernmost fold of the Jura Mountains. The afternoon we spent on the Col du Marchairuz where we discussed the formation processes of geomorphological features typical for karst landscapes such as dolines and karrens. And no karst excursion without a dive into a cave of course: after a climb down a mobile ladder we could study erosion patterns by water on the cave walls and also sedimentary deposits. We ended the first day with a tour in the Grottes de Vallorbe where we marveled at spectacular speleothems.
The second day we started in a beautiful ‘glacière’ in the Val de Travers, thus in an ice-filled cave. Good for cooling down the hot heads and bellies after a delicious dinner and an even more delicious breakfast in our hotel. Only a short ladder had to be conquered this time, but a good balance was an advantage for moving on the ice holding on to the ropes installed by our guides. We continued the trip to Grotte de Môtiers that was the first time mentioned in a letter from Jean-Jacques Rousseau. Here, vermiculations similar as in the Lascaux cave in France are visible on the cave walls, a pattern on the rock surface that is probably produced by bacterial activity. Our last cave of the excursion was the cave of Cotencher close to Neuchâtel. It is one of the oldest paleolithical sites of Switzerland and its sediment sequence has revealed lithic artefacts, faunal remains as well as evidence for the presence of a local glacier 70 ka ago. For our final stop with a focus on applied karst hydrogeology we continued to Twann. Here, the construction of the road tunnel had to be adapted to the important karst conduits draining the catchment area of the Chasseral. Enriched with many new impressions we ended the excursion with a tasting of wines grown on different geological substrates.