We visit the main parts of Montpellier in two hours through 1,000 years of history along twining Medieval streets, Arch of Triumph, courtyards of private mansions, and more. The price is included in the registration fee.
One day excursion to a nearby historic site will be proposed before or after the conference.
A one-day excursion is proposed on July 8th. It will focus on natural granular processes related to hillslope erosion and river transport. We will visit several outcrops along the ‘Hérault’ river near Saint–Bauzille-de-Putois (30 km northward of Montpellier). In this area, the river shows two flow regimes: a) a canyon in which the flow is confined in a bedrock channel, and pebbles impact and erode the bedrock; and b) a large alluvial valley in which pebbles are transported and deposited. We will also observe hillslope granular deposits named stratified scree, composed of dipping layers of angular rock fragments resulting from frost weathering. We will visit the Grotte des Demoiselles, an impressive cave located in a nearby limestone relief. The fee for this excursion covers transport and lunch expenses as well as the entry fee to the "Grotte des Demoiselles" cavern.
This visit will be organised by Alfredo Taboada and Jacques Malavielle from Montpellier University Geosciences. The transport and lunch fees can be payed through the registration page.
Geological excursion: Grains in Nature
|8:00||Departure From Montpellier|
|9:00-12:00||Hillslope processes in the La Lergue valley, Volcanic flows and basalt columns around the Salagou lake|
|12:00-13:30||Picnic lunch by the lake (regional products, swimming area)|
|13:30-16:00||Karst topography and ruin-like landscapes in the Cirque de Moureze Hérault river gorges near Saint-Guilhem-le-Désert|
|16:00-17:30||Visit of the famous Clamouse cave (karstic underground environment)|
A one-day geological excursion is proposed for those interested in discovering amazing landscapes in which granular materials are at the heart of natural erosional processes. We will visit the ‘Cevennes Region’ located Eastward of Montpellier, where river incision and hillslope erosion have sculpted beautiful morphologies such as gorges and pinnacles in vertically-jointed sedimentary rocks.
We will visit four geological sites showing significant examples of erosional processes and natural granular materials:
1) Landslides and scree talus deposits in the “vallée de La Lergue”
We will observe landslide processes along the “vallée de La Lergue” which incises the Larzac plateau along a fractured corridor. The hillslope beneath the plateau exposes a thick sedimentary pile of rocks with varying strength (from weak claystones at the base to massive and fractured dolomites at the top). Large-scale circular landslides affect the entire hillslope, widening the river valley; unstable rock columns adjacent to scarps slowly move downslope, producing rockfalls and topples. Rock material is fragmented by gelifraction forming talus deposits of scree at the foot of the rock scarps.
2) Ancient volcanic flows and inverted topography in the “Salagou lake” area
We will visit the ‘Salagou lake’ area in which red Permian siltstones have been largely eroded by diffusive processes, generating an inverted topography. The relief shows several plateaus overlaid by old quaternary basaltic flows roughly located 100 m above the present river base level. These flows of highly fluid (runny) lavas covered former valley floors and originated from nearby volcanoes active 1 to 2 million years ago. We will observe columnar basalts formed by contractional joints or fractures resulting from the rapid cooling of lava flows. The lateral shapes of these columns are predominantly hexagonal in cross-section. Ancient volcanoes were eroded and only volcanic necks are visible in the landscape. Volcanic necks (or plugs) result from differential weathering and erosion between the former feeder tube of a volcano and its surrounding rocks. Topography inversion results from the hardness of basaltic rocks, which are preserved from erosion compared to the highly erodible red mudstones.
3) Ruin-like landscapes in the ‘cirque de Mourèze’
We will walk along the ‘cirque de Mourèze’ located eastward of the Salagou lake showing impressive ‘ruin-like’ landscapes in dolomitic limestones that have been largely eroded by karstification (dissolution of calcium and magnesium carbonates) over the quaternary period. A special granular material named “grésou” (dolomite sand) is observed at the foot of eroded pinnacles; rock columns and pinnacles have strange morphologies sometimes compared to lunar landscapes.
4) Hérault River gorges and Clamouse karst cave in Saint-Guilhem-le-Désert
The progressive incision of rivers in the Cevennes region which began 5 million years ago has formed extensive cave systems in dolomitic limestones. We will visit the famous Clamouse cave formed by the paleo-Hérault subterranean river system which exposes three different levels of galleries with impressive concretions and solution forms. The cave is located close to the Hérault gorges in which we will observe several mechanisms of river incision: the impact of transported pebbles on bedrock (plucking), abrasion of rock surfaces, cavitation and dissolution which all contribute to erode the substratum over geological time periods.
Figure 1a: Lanscape of the ‘vallée de La Lergue” affected by circular landslides
Figure 1b: Detail of triangular topographic facet indicating the fault scarp of an active landslide
Figure 1c: Interpretation of landslide geometry at depth, beneath the landscape (Figures 1a,b)
Figure 2: Vertical cliff subjected to block falls
Figure 3: Scree talus deposits located at the foot of vertical cliffs
Figure 4: Vertical cliffs subjected to rock falla and rock topples
Figure 5: Volcanic flow remnant located on top of a conic shaped relief (Salagou lake)
Figure 6: Landscape of the Hérault river Near Saint-Guilhem-le-Désert
July is the best period for festivals (music, street theatres, …). Events nearby Montpellier will be listed later.
Follow this link for an extensive list of activities in the south of France.
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