Stage 11: Carcassone to Montpellier

The eleventh stage of this year’s Tour takes us out of the town of Carcassonne, known for its medieval Cité and to the coastal town of Montpellier. We are not quite at the Camargue, the delta of the Rhône River, but tomorrow’s stage to Mont Ventoux takes us a little too far north to catch a glimpse of it, so we’ll take this opportunity to discuss France’s largest wetland.

The Camargue is a triangular delta in between two distributary channels of the Rhône, the Petit- and Grande-Rhônes. The most notable ecosystem of the Camargue are the étangs, shallow saline lagoons which are home to flamingos, which we caught a few glimpses of on today’s stage. Surrounding the étangs are marshes covered in grasses as well as Salicornia and Limonium, the sea lavender. The rest of the Camargue is agricultural land — much of which used to be marshes (Tamisier 1994).

Living throughout the marshy bits of the Camargue are semi-feral bands of Camaraguais horses. These horses are ridden by the gardians, cowboys of the Camargue, who raise cattle on the delta.

Peter Sagan pulled off a stunning win in the crosswinds today tailed by none other than Chris Froome, almost certainly outpacing the Camarguais.

  • Tamisier, Alain, and Patrick Grillas. “A review of habitat changes in the Camargue: an assessment of the effects of the loss of biological diversity on the wintering waterfowl community.” Biological Conservation 70, no. 1 (1994): 39-47.

Stage 10: Escaldes-Engordany to Revel

We leave Andorra after the first rest day and make our way to Revel, in Haute-Garonne. As promised, we crossed the Canal du Midi in Castelnaudary towards the end of the stage. The Canal connects the Mediterranean Sea at Sète to the Canal de Garonne at Toulouse, and the Canal de Garonne and the Garonne River flow to Bordeaux and the Garonne estuary on the Atlantic Ocean. It was constructed in the late 17th century and represents one of the major public works during the reign of Louis XIV.

The dream of connecting the Atlantic to the Mediterranean was common throughout early modern France. The trip around the Iberian Peninsula was just too long and too dangerous to support. But it proved to be harder than most people thought to get water to flow continuously in the canal.

Pierre-Paul Riquet came up with the solution: divert water from the Montagne Noire to the high point of the canal at the Seuil de Narouze. Riquet wrote to Jean-Baptise Colbert, Louis’ finance minister, proposing his design for a canal, and Colbert signed off on the project. Construction began in 1667 with the construction of the rigole de la plaine, Riquet’s ingenious irrigation system, and concluded in 1681, a year after Riquet’s death.

The Bassin de St. Ferreol is yet another artificial lake, constructed to hold water coming from the Montagne Noire, and it was the site of today’s third category climb just before the thrilling breakaway-turned-sprint into Revel led by the trio from Orica-Bikeexchange.

Stage 9: Vielha Val d’Aran to Andorre Arcalis

An exciting mountain stage finished in Andorra amidst a hailstorm. Today, we ask why such thunderstorms are so common in the Pyrenees.

Source: http://images.cyclingtips.com/content/uploads/2016/07/CORVOS_00026811-037.jpg

Wet air from the Mediterranean is funneled up the river valleys of Eastern Spain, depicted nicely in this map from Pineda et al. (2010). As it goes further up the valleys, the air is pushed up in elevation until it reaches Andorra, the country with the highest average elevation in Europe.

The air cools down as it rises until it becomes too cool to hold all of that water it brought up from the Mediterranean, and the water falls out as precipitation. Combine this orographic effect with the large daily fluctuation in temperature that you see in the summer, and you have a large, wet and unstable air mass which results in a convective thunderstorm which drops hail as we saw today.

Thunderstorms are very common in Andorra during the summer, and flash floods from such thunderstorms are one of the major natural hazards Andorra faces (Trapero 1980).

  • Callado, A., and R. Pascual. “Diagnosis and modelling of a summer convective storm over Mediterranean Pyrenees.” Advances in Geosciences 2 (2005): 273-277.
  • Pineda, N., P. Esteban, L. Trapero, X. Soler, and C. Beck. “Circulation types related to lightning activity over Catalonia and the Principality of Andorra.”Physics and Chemistry of the Earth, Parts A/B/C 35, no. 9 (2010): 469-476.
  • Trapero, L., et al. “Mesoscale numerical analysis of the historical November 1982 heavy precipitation event over Andorra (Eastern Pyrenees).” Natural Hazards and Earth System Sciences 13.11 (2013): 2969-2990.

 

 

Stage 8: Pau to Bagnères-de-Luchon

Our first true mountain stage took us back through the Néouvielle massif on the way to the spa town and perennial favorite of the Tour, Bagnères-de-Luchon. Before we hit the climbs today, though, we passed through the town of Lourdes, home to the Sanctuary of Our Lady of Lourdes and the holy water which flows there.

Throughout 1858, a young girl named Bernadette Soubirous witnessed apparitions of a lady at the Grotto of Massabielle. Upon investigation the Catholic Church determined that these were apparitions of the Virgin Mary. The Grotto was made into a holy site, the Sanctuary of Our Lady of Lourdes, and Bernadette was made into a saint.

The water of the spring emerges from the limestone rock of the Massabielle before flowing quickly into the Gave de Pau river (named after the start point of today’s stage) next to the shrine. It is now collected into baths before it flows directly into the river. Some of the water is also collected and bottled for distribution around the world. Indeed, it appears that one can even find Lourdes water just down the street from me in Kenmore Square.

The shrine and story of Saint Bernadette appear in the literary works of both Émile Zola, who was not sold on the shrine, and Franz Werfel, whose The Song of Bernadette is more believing.

At the conclusion of today’s stage in Luchon, we see why Chris Froome is, once again, the strongest and smartest rider in the peloton these days. What an attack on the descent of the Peyresourde!

Stage 7: L’Isle-Jourdain to Lac de Payolle

Today’s stage takes us up and down the Col d’Aspin to finish at the Lac de Payolle. This lake is artificial, like many we’ve seen on the way through the Massif Central.

Hydroelectric power development in France began to grow in the postwar era as France’s economy boomed. A good portion of this development took place in the Pyrenées, especially around the Néouvielle massif just south of today’s finish. The Barrage de Cap-de-Long, completed in 1953,  is the largest of the dams in the area.

orc3a9don_lac_281129

One possibly unintended consequence of the construction of dams in southwestern France has been the opening up of the country to a particular brand of ecotourism (Rodriguez 2012). The Lac de Payolle is a resort and even the Néouvielle massif is now a nature preserve.

An exciting stage for fans of the breakaway today with a great win by Steve Cummings!

  • Rodriguez, Jean-François. “Hydropower landscapes and tourism development in the Pyrenees. From natural resource to cultural heritage.” Journal of Alpine Research| Revue de géographie alpine 100-2 (2012).

Stage 6: Arpajon-sur-Cère to Montauban

The sixth stage took us out of Auvergne and into the Midi-Pyrénées to the town of Montauban, on the Tarn river and home to the Canal de Montech, part of the Canal de Garonne, itself part of the massive Canal des Deux Mers along with the Canal du Midi, which we’ll meet again on Stage 10. At Montech on the Canal de Garonne, there is a very strange contraption called a water slope.

france_-_montech_-_pente_d27eau_-_2005-01-15

A water slope is an alternative to locks in a canal. A lock usually works something like this

That is, a boat goes in at one level, the lock fills up and the boat leaves at another level. The water slope was invented by Jean Aubert as an alternative and installed at Montech and Fonserannes. I can’t seem to find a good GIF, but here’s a video of the water slope at Fonserannes.

There is a concrete slope built on a hill. The boat enters the slope at the bottom of the hill and a gate is closed behind the ship, locking in a wedge of water underneath the boat. This confused me a bit at first, but the boat is sitting on flat water. The hypotenuse of the triangle is on the concrete slope. The gate is then pushed up the hill by railroad locomotives, carrying the wedge of water up with it. When it reaches the top, the water is now level with the rest of the canal and the boat can sail away.

Ingenious, isn’t it? Well, there’s probably a reason why only two of them were ever built. Still, the extensive canal network in the southwest of France is a marvel, and one that we’ll return to when we cross the Canal du Midi in a few days.

Another sprint finish in Montauban on the banks of the Tarn, pulled out at the last second by Mark Cavendish, with a surprise third place from the British newcomer Dan McLay.

And if you ever wanted to watch a 20 minute video of an inactive water slope from a drone, you’re in luck.

Stage 5: Limoges to Le Lioran

We head out of Limoges towards the ski resort of Le Lioran in Auvergne, in the heart of the mountains of the Massif Central. Along the way, we drop briefly into the valley of the Dordogne, which we won’t see again this year, so it’s time to talk about gabarres.

Source: https://upload.wikimedia.org/wikipedia/commons/2/2a/Dordogne1.JPG

The gabarre is a traditional wooden transport ship on the Dordogne, used up to the 19th century to transport goods from Limousin and Auvergne down the river to Bordeaux. The river where we encountered it on today’s stage was not regularly navigable by large boats, which would normally depart from the area around Argentat, laden with timber floated down the river. As in the United States, the rise of the railway led to the demise of inland water transportation on the Dordogne, and hydroelectric dams (as we saw yesterday in the Haute-Vienne) litter the valley above Argentat nowadays.

Source: http://www.gabarres.com/wp-content/uploads/2015/01/historique-6.jpg

A culture of boatmen, les gabariers, arose around this trade. This culture has been extensively explored by Anne-Marie Cocula-Vaillières in her books and articles. I’m particularly excited to look deeper into her analysis of the diaries of one of these boatman from the 17th century.

A stunning breakaway ride from the Belgians Greg van Avermaet and Thomas de Gendt led us away from the Dordogne and into the mountains  at Le Lioran.

  • “The expansion of inland water transport” http://norbert.fr/
  • Cocula, Anne-Marie. “L’activité d’un maître de bateau sur la Dordogne au milieu du XVIIe siècle.” Annales du Midi: revue archéologique, historique et philologique de la France méridionale 82, no. 96 (1970): 21-43.
  • Gilles, Bernard. “Une rivière et une société: la Dordogne. A.-M. Cocula-Vaillieres, Les gens de la rivière de Dordogne.” Revue géographique des Pyrénées et du Sud-Ouest 51, no. 1 (1980): 87-89.

 

Stage 4: Saumur to Limoges

The fourth and longest stage of the 2016 Tour takes us into the valley of the Vienne river, a tributary of the Loire. We spent the latter part of the day in the region of Limousin, home of many lakes and, historically, the French uranium mining industry.

Source: https://upload.wikimedia.org/wikipedia/commons/e/e2/Lac_de_saint-pardoux_avril_2008.JPG

This is the Lac de Saint-Pardoux, which we caught a glimpse of on the way down and which, depending on who you ask, is either a fun place for watersports or a radioactive cesspool. The basin in which the lake sits was mined for uranium from 1953 until 1992 (Royer et al. 2002) by a company called COGEMA, now part of AREVA.

It became clear after the mine was shut down that there was significantly more radioactive waste around the mining sites, particularly in the lake sediments than the company had previously expected (Royer et al. 2002). In 2005, the government to establish in 2005 the Groupe d’Expertise Pluraliste, an advisory body with members from government, academia and industry. The GEP was to study the impact of AREVA’s operations in the Ritord river valley and to examine the options for moving forward with remediation and monitoring. This they did up through 2013, when they published a final report making several recommendations (executive summary in English, PDF).

In any case, the peloton sped past the Lac de Saint-Pardoux today without a second glance on the way to yet another exciting sprint finish with Marcel Kittel just edging out Bryan Coquard on the line.

  • Royer, A., Reyss, J. L. and Decossas, J. L. “Uranium distribution of a lake sediments in a former mining area.” Radioprotection 37 (2002): 69-74.

Stage 3: Granville to Angers

Stage 3 began in Granville, the shellfish port we encountered in Stage 1, and ran down the edge of the Breton department of Ille-et-Vilaine before speeding through Mayenne and the northwestern tip of Maine-et-Loire before a quick finish in Angers. We were treated to some great shots of the Tour passing by the several rivers which converge in Angers, and those rivers are the subject of today’s edition of Les Eaux du Tour.

As we left Brittany, we entered the watershed of the Loire which covers over 100,000 sq. km. in western France. The main stream of the river rises in the Massif Central, and we’ll actually be fairly close to the source (though on the other side of some mountains) when we finish the first individual time trial at La Caverne du Pont-d’Arc.
Source: https://upload.wikimedia.org/wikipedia/commons/9/92/Loire_river_tribs_map.png

We first encountered the streams of the Loire basin when we saw the Verzée join the Oudon in Segré.Source: http://images-01.delcampe-static.net/img_large/auction/000/300/702/438_001.jpg

The Tour takes leave of the rivers for a little while as the Oudon continues flowing to the east where it meets the Mayenne near Le Lion-d’Angers. The Mayenne flows southeast until it meets the Sarthe in a large system of wetlands (and Ramsar site!) called the Basses vallées angevines.

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The wetland pictured above is the Île Saint-Aubin, a triangle formed by the Mayenne and the Sarthe on its two lower sides, which join at the triangle’s southern apex, and a channel connecting the Mayenne to the Sarthe called the Vieille Mayenne. The photo above is looking southeast with the Vieille Mayenne on the left and the Mayenne proper on the right. The city of Angers claims that these wetlands are the third largest in France, after the Rhône delta region called the Camargue and the Marais Poitevin. We’ll pass through Poitou tomorrow too far to the east to see much of the latter, and we’ll skirt the Camargue on stages 11 and 12

Once the Mayenne and the Sarthe join, they are called the Maine. The Maine flows straight through the city of Angers for 11.5 kilometers before joining the Loire south of the city. This is where the Tour rejoined the river, storming across the Pont de la Haute-Chaîne over the Maine before yet another thrilling finish in front of the city hall of Angers given to us by Mark Cavendish et al.

Stage 2: Saint-Lô to Cherbourg-en-Cotentin

We stay on the Cotentin Peninsula for this stage, riding up the west coast this time, just past a few of the estuaries and wetlands that we passed yesterday on the way up from Mont Saint-Michel. We didn’t get as many dramatic views of these as the race passed through the small country roads of Cotentin today, so I’d like to discuss the large body of water sometimes visible off in the background the last couple of days, la Manche, the English Channel. Where does the water in the channel come from, and where does it go? Why are the tides so high at Mont Saint-Michel? Who would win in a race between Peter Sagan and the tides of the English Channel?

The English Channel connects the North Sea to the Atlantic Ocean from the Straits of Dover in the East to the line connecting Land’s End in Cornwall to Ushant in Brittany. The deepest part of the channel is in Hurd’s Deep — number 7 on this map from Mellett et al. (2013). The eastern end of the Channel is much shallower than the western end. Much of the eastern part of the Channel and the southern North Sea used to be a land bridge from Europe to Great Britain called Doggerland, but that’s probably a topic for next year’s Tour starting out in the Rhineland of Germany. Evidence has been accumulating recently that the Channel is the result of a catastrophic megaflood that erupted from a glacial lake in Doggerland (Gupta 2007, Collier 2015).

fig-1-sea-bed-bathymetry-of-the-english-channel-continental-shelf-inset-map-shows

The tides in the English Channel are amplified as water is funneled into the many bays along the channel, rising highest in the Bay of Mont Saint-Michel, as we saw yesterday, and near the mouth of the River Somme in the east (Pingree 1980).

The highest velocities in the channel are at the tip of the Cotentin peninsula at La Hague, near where we finished today’s stage in Cherbourg. The peninsula squeezes the water between France and Britain there, forcing water to rush past La Hague. As this high velocity stream passes through the Channel, it dissipates energy by friction on the sea floor, and more energy is dissipated in the Channel by this mechanism than is dissipated in the entire North Sea (Pingree 1980)!

When we average the flow over a complete tidal cycle, it’s possible that not all of the water which comes into the Channel with the flood tide leaves on the ebb tide. This is called residual circulation, and in the English channel a residual circulation carries water from the Atlantic through the Channel to the North Sea. We can measure this circulation with radar coupled to hydrodynamic models (Sentchev et al. 2006) or with radioisotopes released into the Channel by the nuclear waste processing facility on La Hague (Bailly du Bois et al. 1995).

A thrilling finish today by Peter Sagan just down the road from La Hague. The tidal velocities at La Hague reach up to 15 or 16 kilometers per hour. Peter Sagan was pushing 60 to 70 kilometers per hour during parts of the race today, handily out-cycling the tides. The Channel has him beat on power though, dissipating around 60 gigawatts. Sagan averaged a little over 200 watts today, pushing it up to a kilowatt or so on that last climb, so it’s probably more reliable to get the Channel to power your home, if a little less fun.

I’ll leave you today with a painting by Eduoard Manet of another famous event to happen off Cherbourg: the sinking of the CSS Alabama by the USS Kearsarge in 1864.

Source: https://upload.wikimedia.org/wikipedia/commons/5/56/Édouard_Manet-Kearsarge-Alabama2.jpg

  • Mellett, Claire L., David M. Hodgson, Andrew J. Plater, Barbara Mauz, Ian Selby, and Andreas Lang. “Denudation of the continental shelf between Britain and France at the glacial–interglacial timescale.” Geomorphology 203 (2013): 79-96.
  • Gupta, Sanjeev, Jenny S. Collier, Andy Palmer-Felgate, and Graeme Potter. “Catastrophic flooding origin of shelf valley systems in the English Channel.”Nature 448, no. 7151 (2007): 342-345.
  • Collier, J. S., F. Oggioni, S. Gupta, David García-Moreno, Alain Trentesaux, and Marc De Batist. “Streamlined islands and the English Channel megaflood hypothesis.” Global and Planetary Change 135 (2015): 190-206.
  • Pingree, R. D. “Physical oceanography of the Celtic Sea and English Channel.” Elsevier Oceanography Series 24 (1980): 415-465.
  • Sentchev, Alexei, Max Yaremchuk, and Florent Lyard. “Residual circulation in the English Channel as a dynamically consistent synthesis of shore-based observations of sea level and currents.” Continental shelf research 26, no. 16 (2006): 1884-1904.
  • du Bois, P. Bailly, J. C. Salomon, R. Gandon, and P. Guéguéniat. “A quantitative estimate of English Channel water fluxes into the North Sea from 1987 to 1992 based on radiotracer distribution.” Journal of Marine Systems 6, no. 5 (1995): 457-481.