EuroKarst 2018 in Besançon, France 5 July 2018
Field trip to the upper Jura Mountains – the Mont d’Or area
Overview
Guided by hydrogeologists from the University of Bourgogne - Franche-Comté, the field trip participants will visit a typical karst area of the French upper Jura Mountains, situated close to the French-Swiss border at just 1,5 hour from Besançon city.
The main goal of this excursion is to present some characteristics of the karst hydrogeology in the folded zone of the Jura Mountains, by discovering the main geological features and their influence on the karst behavior of the area.
We will discover the impact of a rail tunnel construction through a wide anticline, which occurred in the early XXth century. Nowadays, this tunnel is still used by trains of great velocity (TGV Lyria) from Paris to Lausanne.
Provisional list of stops:
- Doubs spring: description of the hydrogeological and hydrochemical characteristics of the outlet, which is a perfect example of exclusive recharge by diffuse infiltration; - View and geological description in the upstream sector of the Doubs valley, included in the folded high range of the Jura Mountains (Mt d’Or viewpoint, 1463m); - Mont d’Or railway tunnel: explanation of the consequences of its digging; - the “Conifer” steam railway, giving access to the Fontaine-Ronde spring, one of those exhausted during the tunnel digging; - The Fontaine-Ronde spring is a natural curiosity: every 9 minutes, this intermittent spring emits gas bubbles, the water level, and subsequently the discharge increase. This phenomenon is interpreted as a gas-lift in the karst reservoir; - visit of the Fort Saint-Antoine, an old military construction converted for ripening Comté cheese (“affinage”): 100,000 cheese wheels, each weighing about 40 kg, are salted, rubbed and turned over periodically by automatons.